erdantic.core¶

DEFAULT_EDGE_ATTR `module-attribute` ¶

DEFAULT_EDGE_ATTR = (('dir', 'both'))

Default edge attributes passed to Graphviz.

DEFAULT_GRAPH_ATTR `module-attribute` ¶

DEFAULT_GRAPH_ATTR = (
    ("nodesep", "0.5"),
    ("ranksep", "1.5"),
    ("rankdir", "LR"),
    (
        "label",
        f"Created by erdantic v{__version__} <https://github.com/drivendataorg/erdantic>",
    ),
    (
        "fontname",
        "Times New Roman,Times,Liberation Serif,serif",
    ),
    ("fontsize", "9"),
    ("fontcolor", "gray66"),
)

Default graph attributes passed to Graphviz.

DEFAULT_NODE_ATTR `module-attribute` ¶

DEFAULT_NODE_ATTR = (
    (
        "fontname",
        "Times New Roman,Times,Liberation Serif,serif",
    ),
    ("fontsize", 14),
    ("shape", "plain"),
)

Default node attributes passed to Graphviz.

Cardinality ¶

Bases: Enum

Enumeration of possible cardinality values for a relationship between two data model classes. Cardinality measures the maximum number of associations.

Source code in erdantic/core.py

class Cardinality(Enum):
    """Enumeration of possible cardinality values for a relationship between two data model
    classes. Cardinality measures the maximum number of associations.
    """

    UNSPECIFIED = "unspecified"
    ONE = "one"
    MANY = "many"

    def to_dot(self) -> str:
        """Returns the DOT language specification for the arrowhead styling associated with the
        cardinality value.
        """
        return _CARDINALITY_DOT_MAPPING[self]

to_dot ¶

to_dot() -> str

Returns the DOT language specification for the arrowhead styling associated with the cardinality value.

Source code in erdantic/core.py

def to_dot(self) -> str:
    """Returns the DOT language specification for the arrowhead styling associated with the
    cardinality value.
    """
    return _CARDINALITY_DOT_MAPPING[self]

Edge ¶

Bases: BaseModel

Hold information about a relationship between two data model classes. These represent directed edges in the entity relationship diagram.

Attributes:

Name	Type	Description
`source_model_full_name`	`FullyQualifiedName`	Fully qualified name of the source model, i.e., the model that contains a field that references the target model.
`source_field_name`	`str`	Name of the field on the source model that references the target model.
`target_model_full_name`	`FullyQualifiedName`	Fully qualified name of the target model, i.e., the model that is referenced by the source model's field.
`target_cardinality`	`Cardinality`	Cardinality of the target model in the relationship, e.g., if the relationship is one (source) to many (target), this value will be `Cardinality.MANY`.
`target_modality`	`Modality`	Modality of the target model in the relationship, e.g., if the relationship is one (source) to zero (target), meaning that the target is optional, this value will be `Modality.ZERO`.
`source_cardinality`	`Optional[Cardinality]`	Cardinality of the source model in the relationship. This will never be set for Edges created by erdantic, but you can set it manually to notate an externally known cardinality.
`source_modality`	`Optional[Modality]`	Modality of the source model in the relationship. This will never be set for Edges created by erdantic, but you can set it manually to notate an externally known modality.

Source code in erdantic/core.py

@add_repr_pretty_to_pydantic
class Edge(pydantic.BaseModel):
    """Hold information about a relationship between two data model classes. These represent
    directed edges in the entity relationship diagram.

    Attributes:
        source_model_full_name (FullyQualifiedName): Fully qualified name of the source model,
            i.e., the model that contains a field that references the target model.
        source_field_name (str): Name of the field on the source model that references the target
            model.
        target_model_full_name (FullyQualifiedName): Fully qualified name of the target model,
            i.e., the model that is referenced by the source model's field.
        target_cardinality (Cardinality): Cardinality of the target model in the relationship,
            e.g., if the relationship is one (source) to many (target), this value will be
            `Cardinality.MANY`.
        target_modality (Modality): Modality of the target model in the relationship, e.g., if the
            relationship is one (source) to zero (target), meaning that the target is optional,
            this value will be `Modality.ZERO`.
        source_cardinality (Optional[Cardinality]): Cardinality of the source model in the
            relationship. This will never be set for Edges created by erdantic, but you can set it
            manually to notate an externally known cardinality.
        source_modality (Optional[Modality]): Modality of the source model in the relationship.
            This will never be set for Edges created by erdantic, but you can set it manually to
            notate an externally known modality.
    """

    source_model_full_name: FullyQualifiedName
    source_field_name: str
    target_model_full_name: FullyQualifiedName
    target_cardinality: Cardinality
    target_modality: Modality
    source_cardinality: Cardinality = Cardinality.UNSPECIFIED
    source_modality: Modality = Modality.UNSPECIFIED

    @property
    def key(self) -> str:
        """Returns the key used to identify this instance of Edge in the
        EntityRelationshipDiagram.edges mapping. This value is a hyphenated string of the fields
        `source_model_full_name`, `source_field_name`, and `target_model_full_name`.
        """
        return "-".join(
            str(part)
            for part in (
                self.source_model_full_name,
                self.source_field_name,
                self.target_model_full_name,
            )
        )

    @classmethod
    def from_field_info(cls, target_model: type, source_field_info: FieldInfo) -> Self:
        """Constructor method to create a new instance from a target model instance and a source
        model's FieldInfo.

        Args:
            target_model (type): Target model class.
            source_field_info (FieldInfo): FieldInfo instance for the field on the source model
                that references the target model.

        Returns:
            Self: New instance of Edge.
        """
        is_collection = is_collection_type_of(source_field_info.raw_type, target_model)
        is_nullable = is_nullable_type(source_field_info.raw_type)
        cardinality = Cardinality.MANY if is_collection else Cardinality.ONE
        if is_nullable:
            modality = Modality.ZERO
        else:
            modality = Modality.UNSPECIFIED if is_collection else Modality.ONE
        return cls(
            source_model_full_name=source_field_info.model_full_name,
            source_field_name=source_field_info.name,
            target_model_full_name=FullyQualifiedName.from_object(target_model),
            target_cardinality=cardinality,
            target_modality=modality,
        )

    def target_dot_arrow_shape(self) -> str:
        """Arrow shape specification in Graphviz DOT language for this edge's head (the end at the
        target model). See [Graphviz docs](https://graphviz.org/doc/info/arrows.html) as a
        reference. Shape returned is based on
        [crow's foot notation](https://www.gleek.io/blog/crows-foot-notation) for the
        relationship's cardinality and modality.

        Returns:
            str: DOT language specification for arrow shape of this edge's head
        """
        return self.target_cardinality.to_dot() + self.target_modality.to_dot()

    def source_dot_arrow_shape(self) -> str:
        """Arrow shape specification in Graphviz DOT language for this edge's tail (the end at the
        source model). See [Graphviz docs](https://graphviz.org/doc/info/arrows.html) as a
        reference. Shape returned is based on
        [crow's foot notation](https://www.gleek.io/blog/crows-foot-notation) for the
        relationship's cardinality and modality.

        Returns:
            str: DOT language specification for arrow shape of this edge's tail
        """
        return self.source_cardinality.to_dot() + self.source_modality.to_dot()

key `property` ¶

key: str

Returns the key used to identify this instance of Edge in the EntityRelationshipDiagram.edges mapping. This value is a hyphenated string of the fields source_model_full_name, source_field_name, and target_model_full_name.

from_field_info `classmethod` ¶

from_field_info(
    target_model: type, source_field_info: FieldInfo
) -> Self

Constructor method to create a new instance from a target model instance and a source model's FieldInfo.

Parameters:

Name	Type	Description	Default
`target_model`	`type`	Target model class.	required
`source_field_info`	`FieldInfo`	FieldInfo instance for the field on the source model that references the target model.	required

Returns:

Type	Description
`Self`	New instance of Edge.

Source code in erdantic/core.py

@classmethod
def from_field_info(cls, target_model: type, source_field_info: FieldInfo) -> Self:
    """Constructor method to create a new instance from a target model instance and a source
    model's FieldInfo.

    Args:
        target_model (type): Target model class.
        source_field_info (FieldInfo): FieldInfo instance for the field on the source model
            that references the target model.

    Returns:
        Self: New instance of Edge.
    """
    is_collection = is_collection_type_of(source_field_info.raw_type, target_model)
    is_nullable = is_nullable_type(source_field_info.raw_type)
    cardinality = Cardinality.MANY if is_collection else Cardinality.ONE
    if is_nullable:
        modality = Modality.ZERO
    else:
        modality = Modality.UNSPECIFIED if is_collection else Modality.ONE
    return cls(
        source_model_full_name=source_field_info.model_full_name,
        source_field_name=source_field_info.name,
        target_model_full_name=FullyQualifiedName.from_object(target_model),
        target_cardinality=cardinality,
        target_modality=modality,
    )

source_dot_arrow_shape ¶

source_dot_arrow_shape() -> str

Arrow shape specification in Graphviz DOT language for this edge's tail (the end at the source model). See Graphviz docs as a reference. Shape returned is based on crow's foot notation for the relationship's cardinality and modality.

Returns:

Type	Description
`str`	DOT language specification for arrow shape of this edge's tail

Source code in erdantic/core.py

def source_dot_arrow_shape(self) -> str:
    """Arrow shape specification in Graphviz DOT language for this edge's tail (the end at the
    source model). See [Graphviz docs](https://graphviz.org/doc/info/arrows.html) as a
    reference. Shape returned is based on
    [crow's foot notation](https://www.gleek.io/blog/crows-foot-notation) for the
    relationship's cardinality and modality.

    Returns:
        str: DOT language specification for arrow shape of this edge's tail
    """
    return self.source_cardinality.to_dot() + self.source_modality.to_dot()

target_dot_arrow_shape ¶

target_dot_arrow_shape() -> str

Arrow shape specification in Graphviz DOT language for this edge's head (the end at the target model). See Graphviz docs as a reference. Shape returned is based on crow's foot notation for the relationship's cardinality and modality.

Returns:

Type	Description
`str`	DOT language specification for arrow shape of this edge's head

Source code in erdantic/core.py

def target_dot_arrow_shape(self) -> str:
    """Arrow shape specification in Graphviz DOT language for this edge's head (the end at the
    target model). See [Graphviz docs](https://graphviz.org/doc/info/arrows.html) as a
    reference. Shape returned is based on
    [crow's foot notation](https://www.gleek.io/blog/crows-foot-notation) for the
    relationship's cardinality and modality.

    Returns:
        str: DOT language specification for arrow shape of this edge's head
    """
    return self.target_cardinality.to_dot() + self.target_modality.to_dot()

EntityRelationshipDiagram ¶

Bases: BaseModel

Holds information about an entity relationship diagram for a set of data model classes and their relationships, and provides methods to render the diagram.

Attributes:

Name	Type	Description
`models`	`SortedDict[str, ModelInfo]`	Mapping of ModelInfo instances for models included in the diagram. Each key is the string representation of the fully qualified name of the model.
`edges`	`SortedSet[Edge]`	Set of edges representing relationships between the models.

Source code in erdantic/core.py

class EntityRelationshipDiagram(pydantic.BaseModel):
    """Holds information about an entity relationship diagram for a set of data model classes and
    their relationships, and provides methods to render the diagram.

    Attributes:
        models (SortedDict[str, ModelInfo]): Mapping of ModelInfo instances for models included
            in the diagram. Each key is the string representation of the fully qualified name of
            the model.
        edges (SortedSet[Edge]): Set of edges representing relationships between the models.
    """

    models: SortedDict[str, ModelInfo] = SortedDict()
    edges: SortedDict[str, Edge] = SortedDict()

    model_config = pydantic.ConfigDict(
        validate_default=True,
    )

    @property
    def _model_info_cls(self) -> Type[ModelInfo]:
        """Returns the model info class used by this diagram class. For the normal
        EntityRelationshipDiagram class, this is erdantic.core.ModelInfo."""
        annotation = self.model_fields["models"].annotation
        args = get_args(annotation)
        return args[1]

    @property
    def _edge_cls(self) -> Type[Edge]:
        """Returns the edge class used by this diagram class. For the normal
        EntityRelationshipDiagram class, this is erdantic.core.Edge."""
        annotation = self.model_fields["edges"].annotation
        args = get_args(annotation)
        return args[1]

    def _add_if_model(self, model: type, recurse: bool) -> bool:
        """Private recursive method to add a model to the diagram."""
        try:
            key = str(FullyQualifiedName.from_object(model))
        except AttributeError as e:
            # May get typing special forms that don't have __qualname__ attribute
            # These are not going to be models
            if "__qualname__" in str(e):
                return False
            raise
        if key not in self.models:
            try:
                model_info = self._model_info_cls.from_raw_model(model)
                self.models[key] = model_info
                logger.debug("Sucessfully added model '%s'.", key)
                if recurse:
                    logger.debug("Searching fields of '%s' for other models...", key)
                    for field_info in model_info.fields.values():
                        logger.debug(
                            "Analyzing model '%s' field '%s' of type '%s'...",
                            key,
                            field_info.name,
                            field_info.type_name,
                        )
                        try:
                            for arg in get_recursive_args(field_info.raw_type):
                                is_model = self._add_if_model(arg, recurse=recurse)
                                if is_model:
                                    edge = self._edge_cls.from_field_info(arg, field_info)
                                    self.edges[edge.key] = edge
                                    logger.debug(
                                        "Added edge from model '%s' field '%s' to model '%s'.",
                                        edge.source_model_full_name,
                                        edge.source_field_name,
                                        edge.target_model_full_name,
                                    )
                        except _UnevaluatedForwardRefError as e:
                            raise UnevaluatedForwardRefError(
                                model_full_name=model_info.full_name,
                                field_name=field_info.name,
                                forward_ref=e.forward_ref,
                            )
            except UnknownModelTypeError:
                return False
        else:
            logger.debug("Model '%s' already exists in diagram.", key)
        return True

    def add_model(self, model: type, recurse=True):
        """Add a data model class to the diagram.

        Args:
            model (type): Data model class to add to the diagram.
            recurse (bool, optional): Whether to recursively add models referenced by fields of
                the given model. Defaults to True.

        Raises:
            UnknownModelTypeError: If the model is not recognized as a data model class type that
                is supported by registered plugins.
            UnresolvableForwardRefError: If the model contains a forward reference that cannot be
                automatically resolved.
        """
        logger.info("Adding model '%s' to diagram...", typenames(model))
        is_model = self._add_if_model(model, recurse=recurse)
        if not is_model:
            raise UnknownModelTypeError(model=model, available_plugins=list_plugins())

    def draw(
        self,
        out: Union[str, os.PathLike],
        graph_attr: Optional[Mapping[str, Any]] = None,
        node_attr: Optional[Mapping[str, Any]] = None,
        edge_attr: Optional[Mapping[str, Any]] = None,
        **kwargs,
    ):
        """Render entity relationship diagram for given data model classes to file. The file format
        can be inferred from the file extension. Typical formats include '.png', '.svg', and
        '.pdf'.

        Args:
            out (str | os.PathLike): Output file path for rendered diagram.
            graph_attr (Mapping[str, Any] | None, optional): Override any graph attributes on
                the `pygraphviz.AGraph` instance. Defaults to None.
            node_attr (Mapping[str, Any] | None, optional): Override any node attributes for all
                nodes on the `pygraphviz.AGraph` instance. Defaults to None.
            edge_attr (Mapping[str, Any] | None, optional): Override any edge attributes for all
                edges on the `pygraphviz.AGraph` instance. Defaults to None.
            **kwargs: Additional keyword arguments to
                [`pygraphviz.AGraph.draw`][pygraphviz.AGraph.draw].
        """
        logger.info("Rendering diagram to %s", out)
        self.to_graphviz(
            graph_attr=graph_attr,
            node_attr=node_attr,
            edge_attr=edge_attr,
        ).draw(out, prog="dot", **kwargs)

    def to_graphviz(
        self,
        graph_attr: Optional[Mapping[str, Any]] = None,
        node_attr: Optional[Mapping[str, Any]] = None,
        edge_attr: Optional[Mapping[str, Any]] = None,
    ) -> pgv.AGraph:
        """Return [`pygraphviz.AGraph`][pygraphviz.agraph.AGraph] instance for diagram.

        Args:
            graph_attr (Mapping[str, Any] | None, optional): Override any graph attributes on
                the `pygraphviz.AGraph` instance. Defaults to None.
            node_attr (Mapping[str, Any] | None, optional): Override any node attributes for all
                nodes on the `pygraphviz.AGraph` instance. Defaults to None.
            edge_attr (Mapping[str, Any] | None, optional): Override any edge attributes for all
                edges on the `pygraphviz.AGraph` instance. Defaults to None.

        Returns:
            pygraphviz.AGraph: graph object for diagram
        """
        g = pgv.AGraph(
            name="Entity Relationship Diagram created by erdantic",
            directed=True,
            strict=False,
        )
        g.graph_attr.update(DEFAULT_GRAPH_ATTR)
        g.graph_attr.update(graph_attr or {})
        g.node_attr.update(DEFAULT_NODE_ATTR)
        g.node_attr.update(node_attr or {})
        g.edge_attr.update(DEFAULT_EDGE_ATTR)
        g.edge_attr.update(edge_attr or {})
        for full_name, model_info in self.models.items():
            g.add_node(
                full_name,
                label=model_info.to_dot_label(),
                tooltip=model_info.description.replace("\n", "&#xA;"),
            )
        for edge in self.edges.values():
            g.add_edge(
                edge.source_model_full_name,
                edge.target_model_full_name,
                tailport=f"{edge.source_field_name}:e",
                headport="_root:w",
                arrowhead=edge.target_dot_arrow_shape(),
                arrowtail=edge.source_dot_arrow_shape(),
            )
        return g

    def to_dot(
        self,
        graph_attr: Optional[Mapping[str, Any]] = None,
        node_attr: Optional[Mapping[str, Any]] = None,
        edge_attr: Optional[Mapping[str, Any]] = None,
    ) -> str:
        """Generate Graphviz [DOT language](https://graphviz.org/doc/info/lang.html) representation
        of entity relationship diagram for given data model classes.

        Args:
            graph_attr (Mapping[str, Any] | None, optional): Override any graph attributes on
                the `pygraphviz.AGraph` instance. Defaults to None.
            node_attr (Mapping[str, Any] | None, optional): Override any node attributes for all
                nodes on the `pygraphviz.AGraph` instance. Defaults to None.
            edge_attr (Mapping[str, Any] | None, optional): Override any edge attributes for all
                edges on the `pygraphviz.AGraph` instance. Defaults to None.

        Returns:
            str: DOT language representation of diagram
        """
        return self.to_graphviz(
            graph_attr=graph_attr,
            node_attr=node_attr,
            edge_attr=edge_attr,
        ).string()

    def _repr_pretty_(self, p, cycle):
        """IPython special method to pretty-print an object."""
        try:
            # Try using rich if it's available, since rich is nicer
            import rich  # type: ignore [import-not-found]

            rich.print(self)
        except ModuleNotFoundError:
            if cycle:
                p.text(repr(self))
            else:
                with p.group(1, f"{self.__class__.__name__}(", ")"):
                    # Render models as a dictionary with ModelInfo objects abbreviated
                    p.text("models=")
                    p.pretty(
                        {k: ellipsis_arg_repr_factory(type(v)) for k, v in self.models.items()}
                    )
                    p.text(",")
                    p.breakable()
                    # Render edges as a dictionary with Edge objects abbreviated
                    p.text("edges=")
                    p.pretty(
                        {k: ellipsis_arg_repr_factory(type(v)) for k, v in self.edges.items()}
                    )
                    p.breakable()

    def _repr_png_(self) -> bytes:
        """IPython special method to display object as a PNG image."""
        graph = self.to_graphviz()
        return graph.draw(prog="dot", format="png")

    def _repr_svg_(self) -> str:
        """IPython special method to display object as an SVG image."""
        graph = self.to_graphviz()
        return graph.draw(prog="dot", format="svg").decode(graph.encoding)

    def __rich_repr__(self):
        """Rich special method to format the representation of an object."""
        yield "models", {k: ellipsis_arg_repr_factory(type(v)) for k, v in self.models.items()}
        yield "edges", {k: ellipsis_arg_repr_factory(type(v)) for k, v in self.edges.items()}

add_model ¶

add_model(model: type, recurse=True)

Add a data model class to the diagram.

Parameters:

Name	Type	Description	Default
`model`	`type`	Data model class to add to the diagram.	required
`recurse`	`bool`	Whether to recursively add models referenced by fields of the given model. Defaults to True.	`True`

Raises:

Type	Description
`UnknownModelTypeError`	If the model is not recognized as a data model class type that is supported by registered plugins.
`UnresolvableForwardRefError`	If the model contains a forward reference that cannot be automatically resolved.

Source code in erdantic/core.py

def add_model(self, model: type, recurse=True):
    """Add a data model class to the diagram.

    Args:
        model (type): Data model class to add to the diagram.
        recurse (bool, optional): Whether to recursively add models referenced by fields of
            the given model. Defaults to True.

    Raises:
        UnknownModelTypeError: If the model is not recognized as a data model class type that
            is supported by registered plugins.
        UnresolvableForwardRefError: If the model contains a forward reference that cannot be
            automatically resolved.
    """
    logger.info("Adding model '%s' to diagram...", typenames(model))
    is_model = self._add_if_model(model, recurse=recurse)
    if not is_model:
        raise UnknownModelTypeError(model=model, available_plugins=list_plugins())

draw ¶

draw(
    out: Union[str, PathLike],
    graph_attr: Optional[Mapping[str, Any]] = None,
    node_attr: Optional[Mapping[str, Any]] = None,
    edge_attr: Optional[Mapping[str, Any]] = None,
    **kwargs
)

Render entity relationship diagram for given data model classes to file. The file format can be inferred from the file extension. Typical formats include '.png', '.svg', and '.pdf'.

Parameters:

Name	Type	Description	Default
`out`	`str \| PathLike`	Output file path for rendered diagram.	required
`graph_attr`	`Mapping[str, Any] \| None`	Override any graph attributes on the `pygraphviz.AGraph` instance. Defaults to None.	`None`
`node_attr`	`Mapping[str, Any] \| None`	Override any node attributes for all nodes on the `pygraphviz.AGraph` instance. Defaults to None.	`None`
`edge_attr`	`Mapping[str, Any] \| None`	Override any edge attributes for all edges on the `pygraphviz.AGraph` instance. Defaults to None.	`None`
`**kwargs`		Additional keyword arguments to `pygraphviz.AGraph.draw`.	`{}`

Source code in erdantic/core.py

def draw(
    self,
    out: Union[str, os.PathLike],
    graph_attr: Optional[Mapping[str, Any]] = None,
    node_attr: Optional[Mapping[str, Any]] = None,
    edge_attr: Optional[Mapping[str, Any]] = None,
    **kwargs,
):
    """Render entity relationship diagram for given data model classes to file. The file format
    can be inferred from the file extension. Typical formats include '.png', '.svg', and
    '.pdf'.

    Args:
        out (str | os.PathLike): Output file path for rendered diagram.
        graph_attr (Mapping[str, Any] | None, optional): Override any graph attributes on
            the `pygraphviz.AGraph` instance. Defaults to None.
        node_attr (Mapping[str, Any] | None, optional): Override any node attributes for all
            nodes on the `pygraphviz.AGraph` instance. Defaults to None.
        edge_attr (Mapping[str, Any] | None, optional): Override any edge attributes for all
            edges on the `pygraphviz.AGraph` instance. Defaults to None.
        **kwargs: Additional keyword arguments to
            [`pygraphviz.AGraph.draw`][pygraphviz.AGraph.draw].
    """
    logger.info("Rendering diagram to %s", out)
    self.to_graphviz(
        graph_attr=graph_attr,
        node_attr=node_attr,
        edge_attr=edge_attr,
    ).draw(out, prog="dot", **kwargs)

to_dot ¶

to_dot(
    graph_attr: Optional[Mapping[str, Any]] = None,
    node_attr: Optional[Mapping[str, Any]] = None,
    edge_attr: Optional[Mapping[str, Any]] = None,
) -> str

Generate Graphviz DOT language representation of entity relationship diagram for given data model classes.

Parameters:

Name	Type	Description	Default
`graph_attr`	`Mapping[str, Any] \| None`	Override any graph attributes on the `pygraphviz.AGraph` instance. Defaults to None.	`None`
`node_attr`	`Mapping[str, Any] \| None`	Override any node attributes for all nodes on the `pygraphviz.AGraph` instance. Defaults to None.	`None`
`edge_attr`	`Mapping[str, Any] \| None`	Override any edge attributes for all edges on the `pygraphviz.AGraph` instance. Defaults to None.	`None`

Returns:

Type	Description
`str`	DOT language representation of diagram

Source code in erdantic/core.py

def to_dot(
    self,
    graph_attr: Optional[Mapping[str, Any]] = None,
    node_attr: Optional[Mapping[str, Any]] = None,
    edge_attr: Optional[Mapping[str, Any]] = None,
) -> str:
    """Generate Graphviz [DOT language](https://graphviz.org/doc/info/lang.html) representation
    of entity relationship diagram for given data model classes.

    Args:
        graph_attr (Mapping[str, Any] | None, optional): Override any graph attributes on
            the `pygraphviz.AGraph` instance. Defaults to None.
        node_attr (Mapping[str, Any] | None, optional): Override any node attributes for all
            nodes on the `pygraphviz.AGraph` instance. Defaults to None.
        edge_attr (Mapping[str, Any] | None, optional): Override any edge attributes for all
            edges on the `pygraphviz.AGraph` instance. Defaults to None.

    Returns:
        str: DOT language representation of diagram
    """
    return self.to_graphviz(
        graph_attr=graph_attr,
        node_attr=node_attr,
        edge_attr=edge_attr,
    ).string()

to_graphviz ¶

to_graphviz(
    graph_attr: Optional[Mapping[str, Any]] = None,
    node_attr: Optional[Mapping[str, Any]] = None,
    edge_attr: Optional[Mapping[str, Any]] = None,
) -> AGraph

Return pygraphviz.AGraph instance for diagram.

Parameters:

Name	Type	Description	Default
`graph_attr`	`Mapping[str, Any] \| None`	Override any graph attributes on the `pygraphviz.AGraph` instance. Defaults to None.	`None`
`node_attr`	`Mapping[str, Any] \| None`	Override any node attributes for all nodes on the `pygraphviz.AGraph` instance. Defaults to None.	`None`
`edge_attr`	`Mapping[str, Any] \| None`	Override any edge attributes for all edges on the `pygraphviz.AGraph` instance. Defaults to None.	`None`

Returns:

Type	Description
`AGraph`	graph object for diagram

Source code in erdantic/core.py

def to_graphviz(
    self,
    graph_attr: Optional[Mapping[str, Any]] = None,
    node_attr: Optional[Mapping[str, Any]] = None,
    edge_attr: Optional[Mapping[str, Any]] = None,
) -> pgv.AGraph:
    """Return [`pygraphviz.AGraph`][pygraphviz.agraph.AGraph] instance for diagram.

    Args:
        graph_attr (Mapping[str, Any] | None, optional): Override any graph attributes on
            the `pygraphviz.AGraph` instance. Defaults to None.
        node_attr (Mapping[str, Any] | None, optional): Override any node attributes for all
            nodes on the `pygraphviz.AGraph` instance. Defaults to None.
        edge_attr (Mapping[str, Any] | None, optional): Override any edge attributes for all
            edges on the `pygraphviz.AGraph` instance. Defaults to None.

    Returns:
        pygraphviz.AGraph: graph object for diagram
    """
    g = pgv.AGraph(
        name="Entity Relationship Diagram created by erdantic",
        directed=True,
        strict=False,
    )
    g.graph_attr.update(DEFAULT_GRAPH_ATTR)
    g.graph_attr.update(graph_attr or {})
    g.node_attr.update(DEFAULT_NODE_ATTR)
    g.node_attr.update(node_attr or {})
    g.edge_attr.update(DEFAULT_EDGE_ATTR)
    g.edge_attr.update(edge_attr or {})
    for full_name, model_info in self.models.items():
        g.add_node(
            full_name,
            label=model_info.to_dot_label(),
            tooltip=model_info.description.replace("\n", "&#xA;"),
        )
    for edge in self.edges.values():
        g.add_edge(
            edge.source_model_full_name,
            edge.target_model_full_name,
            tailport=f"{edge.source_field_name}:e",
            headport="_root:w",
            arrowhead=edge.target_dot_arrow_shape(),
            arrowtail=edge.source_dot_arrow_shape(),
        )
    return g

FieldInfo ¶

Bases: BaseModel

Holds information about a field of an analyzed data model class.

Attributes:

Name	Type	Description
`model_full_name`	`FullyQualifiedName`	Fully qualified name of the data model class that the field belongs to.
`name`	`str`	Name of the field.
`type_name`	`str`	String representation of the field's type.

Source code in erdantic/core.py

@add_repr_pretty_to_pydantic
class FieldInfo(pydantic.BaseModel):
    """Holds information about a field of an analyzed data model class.

    Attributes:
        model_full_name (FullyQualifiedName): Fully qualified name of the data model class that
            the field belongs to.
        name (str): Name of the field.
        type_name (str): String representation of the field's type.
    """

    model_full_name: FullyQualifiedName
    name: str
    type_name: str

    model_config = pydantic.ConfigDict(
        extra="forbid",
        protected_namespaces=(),
    )

    _dot_row_template = """<tr><td>{name}</td><td port="{name}">{type_name}</td></tr>"""

    _raw_type: Optional[type] = pydantic.PrivateAttr(None)

    @classmethod
    def from_raw_type(cls, model_full_name: FullyQualifiedName, name: str, raw_type: type) -> Self:
        """Constructor method to create a new instance from a raw type annotation.

        Args:
            model_full_name (FullyQualifiedName): Fully qualified name of the data model class that
                the field belongs to.
            name (str): Name of field.
            raw_type (type): Type annotation.

        Returns:
            Self: _description_
        """
        if get_origin(raw_type) is Annotated:
            # Drop the Annotated extra metadata for the string representation
            type_name = typenames(get_args(raw_type)[0], remove_modules=REMOVE_ALL_MODULES)
        else:
            type_name = typenames(raw_type, remove_modules=REMOVE_ALL_MODULES)
        field_info = cls(
            model_full_name=model_full_name,
            name=name,
            type_name=type_name,
        )
        field_info._raw_type = raw_type
        return field_info

    @property
    def key(self) -> str:
        """Returns the key used to identify this instance of FieldInfo in the ModelInfo.fields
        mapping. This value is the value in the 'name' field.
        """
        return self.name

    @property
    def raw_type(self) -> type:
        """Returns the raw type annotation of the field. This is a cached property. If the raw
        type is not already known, it will attempt to import the data model class and reextract
        the field's type annotation.

        Raises:
            FieldNotFoundError: _description_
            UnknownModelTypeError: _description_

        Returns:
            type: Type annotation.
        """
        if self._raw_type is None:
            model = self.model_full_name.import_object()
            get_fields_fn = identify_field_extractor_fn(model)
            if get_fields_fn:
                for field_info in get_fields_fn(model):
                    if field_info.name == self.name:
                        self._raw_type = field_info.raw_type
                        break
                else:
                    raise FieldNotFoundError(
                        name=self.name, obj=model, model_full_name=self.model_full_name
                    )
            else:
                raise UnknownModelTypeError(model=model, available_plugins=list_plugins())
        return self._raw_type

    def __eq__(self, other: Any) -> bool:
        if not isinstance(other, FieldInfo):
            return NotImplemented
        return self.model_dump() == other.model_dump()

    def to_dot_row(self) -> str:
        """Returns the DOT language "HTML-like" syntax specification of a row detailing this field
        that is part of a table describing the field's parent data model. It is used as part the
        `label` attribute of data model's node in the graph's DOT representation.

        Returns:
            str: DOT language for table row
        """
        return self._dot_row_template.format(name=self.name, type_name=self.type_name)

key `property` ¶

key: str

Returns the key used to identify this instance of FieldInfo in the ModelInfo.fields mapping. This value is the value in the 'name' field.

raw_type `property` ¶

raw_type: type

Returns the raw type annotation of the field. This is a cached property. If the raw type is not already known, it will attempt to import the data model class and reextract the field's type annotation.

Raises:

Type	Description
`FieldNotFoundError`	description
`UnknownModelTypeError`	description

Returns:

Type	Description
`type`	Type annotation.

from_raw_type `classmethod` ¶

from_raw_type(
    model_full_name: FullyQualifiedName,
    name: str,
    raw_type: type,
) -> Self

Constructor method to create a new instance from a raw type annotation.

Parameters:

Name	Type	Description	Default
`model_full_name`	`FullyQualifiedName`	Fully qualified name of the data model class that the field belongs to.	required
`name`	`str`	Name of field.	required
`raw_type`	`type`	Type annotation.	required

Returns:

Type	Description
`Self`	description

Source code in erdantic/core.py

@classmethod
def from_raw_type(cls, model_full_name: FullyQualifiedName, name: str, raw_type: type) -> Self:
    """Constructor method to create a new instance from a raw type annotation.

    Args:
        model_full_name (FullyQualifiedName): Fully qualified name of the data model class that
            the field belongs to.
        name (str): Name of field.
        raw_type (type): Type annotation.

    Returns:
        Self: _description_
    """
    if get_origin(raw_type) is Annotated:
        # Drop the Annotated extra metadata for the string representation
        type_name = typenames(get_args(raw_type)[0], remove_modules=REMOVE_ALL_MODULES)
    else:
        type_name = typenames(raw_type, remove_modules=REMOVE_ALL_MODULES)
    field_info = cls(
        model_full_name=model_full_name,
        name=name,
        type_name=type_name,
    )
    field_info._raw_type = raw_type
    return field_info

to_dot_row ¶

to_dot_row() -> str

Returns the DOT language "HTML-like" syntax specification of a row detailing this field that is part of a table describing the field's parent data model. It is used as part the label attribute of data model's node in the graph's DOT representation.

Returns:

Type	Description
`str`	DOT language for table row

Source code in erdantic/core.py

def to_dot_row(self) -> str:
    """Returns the DOT language "HTML-like" syntax specification of a row detailing this field
    that is part of a table describing the field's parent data model. It is used as part the
    `label` attribute of data model's node in the graph's DOT representation.

    Returns:
        str: DOT language for table row
    """
    return self._dot_row_template.format(name=self.name, type_name=self.type_name)

FullyQualifiedName ¶

Bases: BaseModel

Holds the fully qualified name components (module and qualified name) of a Python object. This is used to uniquely identify an object, can be used to import it.

Attributes:

Name	Type	Description
`module`	`str`	Name of the module that the object is defined in.
`qual_name`	`str`	Qualified name of the object.

Source code in erdantic/core.py

@total_ordering
class FullyQualifiedName(pydantic.BaseModel):
    """Holds the fully qualified name components (module and qualified name) of a Python object.
    This is used to uniquely identify an object, can be used to import it.

    Attributes:
        module (str): Name of the module that the object is defined in.
        qual_name (str): Qualified name of the object.
    """

    module: str
    qual_name: str

    @classmethod
    def from_object(cls, obj: Any) -> Self:
        """Constructor method to create a new instance from a Python object.

        Args:
            obj (Any): Python object.

        Returns:
            Self: Fully qualified name of the object.
        """
        return cls(module=obj.__module__, qual_name=obj.__qualname__)

    def __hash__(self) -> int:
        return hash((self.module, self.qual_name))

    def __str__(self) -> str:
        return f"{self.module}.{self.qual_name}"

    def import_object(self) -> Any:
        """Imports the object from the module and returns it.

        Returns:
            Any: Object referenced by this FullyQualifiedName instance.
        """
        module = import_module(self.module)
        obj = module
        for name in self.qual_name.split("."):
            obj = getattr(obj, name)
        return obj

    def __lt__(self, other: Self) -> bool:
        if not isinstance(other, FullyQualifiedName):
            return NotImplemented
        return (self.module, self.qual_name) < (other.module, other.qual_name)

from_object `classmethod` ¶

from_object(obj: Any) -> Self

Constructor method to create a new instance from a Python object.

Parameters:

Name	Type	Description	Default
`obj`	`Any`	Python object.	required

Returns:

Type	Description
`Self`	Fully qualified name of the object.

Source code in erdantic/core.py

@classmethod
def from_object(cls, obj: Any) -> Self:
    """Constructor method to create a new instance from a Python object.

    Args:
        obj (Any): Python object.

    Returns:
        Self: Fully qualified name of the object.
    """
    return cls(module=obj.__module__, qual_name=obj.__qualname__)

import_object ¶

import_object() -> Any

Imports the object from the module and returns it.

Returns:

Type	Description
`Any`	Object referenced by this FullyQualifiedName instance.

Source code in erdantic/core.py

def import_object(self) -> Any:
    """Imports the object from the module and returns it.

    Returns:
        Any: Object referenced by this FullyQualifiedName instance.
    """
    module = import_module(self.module)
    obj = module
    for name in self.qual_name.split("."):
        obj = getattr(obj, name)
    return obj

Modality ¶

Bases: Enum

Enumeration of possible modality values for a relationship between two data model classes. Modality measures the minimum number of associations.

Source code in erdantic/core.py

class Modality(Enum):
    """Enumeration of possible modality values for a relationship between two data model
    classes. Modality measures the minimum number of associations.
    """

    UNSPECIFIED = "unspecified"
    ZERO = "zero"
    ONE = "one"

    def to_dot(self) -> str:
        """Returns the DOT language specification for the arrowhead styling associated with the
        modality value.
        """
        return _MODALITY_DOT_MAPPING[self]

to_dot ¶

to_dot() -> str

Returns the DOT language specification for the arrowhead styling associated with the modality value.

Source code in erdantic/core.py

def to_dot(self) -> str:
    """Returns the DOT language specification for the arrowhead styling associated with the
    modality value.
    """
    return _MODALITY_DOT_MAPPING[self]

ModelInfo ¶

Bases: BaseModel, Generic[_ModelType]

Holds information about an analyzed data model class.

Attributes:

Name	Type	Description
`full_name`	`FullyQualifiedName`	Fully qualified name of the data model class.
`name`	`str`	Name of the data model class.
`fields`	`Dict[str, FieldInfo]`	A mapping to FieldInfo instances for each field of the data model class.
`description`	`str`	Docstring or other description of the data model class.

Source code in erdantic/core.py

@add_repr_pretty_to_pydantic
class ModelInfo(pydantic.BaseModel, Generic[_ModelType]):
    """Holds information about an analyzed data model class.

    Attributes:
        full_name (FullyQualifiedName): Fully qualified name of the data model class.
        name (str): Name of the data model class.
        fields (Dict[str, FieldInfo]): A mapping to FieldInfo instances for each field of the data
            model class.
        description (str): Docstring or other description of the data model class.
    """

    full_name: FullyQualifiedName
    name: str
    fields: Dict[str, FieldInfo]
    description: str = ""

    model_config = pydantic.ConfigDict(
        extra="forbid",
    )

    _dot_table_template = textwrap.dedent(
        """\
        <<table border="0" cellborder="1" cellspacing="0">
        <tr><td port="_root" colspan="{num_cols}"><b>{name}</b></td></tr>
        {rows}
        </table>>
        """
    )

    _raw_model: Optional[_ModelType] = pydantic.PrivateAttr(None)

    @classmethod
    def from_raw_model(cls, raw_model: _ModelType) -> Self:
        """Constructor method to create a new instance from a raw data model class.

        Args:
            raw_model (type): Data model class.

        Returns:
            Self: New instance of ModelInfo.
        """
        get_fields_fn = identify_field_extractor_fn(raw_model)
        if not get_fields_fn:
            raise UnknownModelTypeError(model=raw_model, available_plugins=list_plugins())

        full_name = FullyQualifiedName.from_object(raw_model)
        description = str(full_name)
        docstring = inspect.getdoc(raw_model)
        if docstring:
            description += "\n\n" + docstring + "\n"

        model_info = cls(
            full_name=full_name,
            name=raw_model.__name__,
            fields={field_info.name: field_info for field_info in get_fields_fn(raw_model)},
            description=description,
        )
        model_info._raw_model = raw_model
        return model_info

    @property
    def key(self) -> str:
        """Returns the key used to identify this instance of ModelInfo in the
        EntityRelationshipDiagram.models mapping. This value is the string representation of the
        `full_name` field.
        """
        return str(self.full_name)

    @property
    def raw_model(self) -> _ModelType:
        """Returns the raw data model class. This is a cached property. If the raw model is not
        already known, it will attempt to import the data model class.
        """
        if self._raw_model is None:
            self._raw_model = self.full_name.import_object()
        return self._raw_model

    def __eq__(self, other: Any) -> bool:
        if not isinstance(other, ModelInfo):
            return NotImplemented
        return self.model_dump() == other.model_dump()

    def to_dot_label(self) -> str:
        """Returns the DOT language "HTML-like" syntax specification of a table for this data
        model. It is used as the `label` attribute of data model's node in the graph's DOT
        representation.

        Returns:
            str: DOT language for table
        """
        # Get number of columns dynamically from first row
        num_cols = next(iter(self.fields.values())).to_dot_row().count("<td")
        # Concatenate DOT of all rows together
        rows = "\n".join(field_info.to_dot_row() for field_info in self.fields.values()) + "\n"
        return self._dot_table_template.format(
            name=self.name, num_cols=num_cols, rows=rows
        ).replace("\n", "")

key `property` ¶

key: str

Returns the key used to identify this instance of ModelInfo in the EntityRelationshipDiagram.models mapping. This value is the string representation of the full_name field.

raw_model `property` ¶

raw_model: _ModelType

Returns the raw data model class. This is a cached property. If the raw model is not already known, it will attempt to import the data model class.

from_raw_model `classmethod` ¶

from_raw_model(raw_model: _ModelType) -> Self

Constructor method to create a new instance from a raw data model class.

Parameters:

Name	Type	Description	Default
`raw_model`	`type`	Data model class.	required

Returns:

Type	Description
`Self`	New instance of ModelInfo.

Source code in erdantic/core.py

@classmethod
def from_raw_model(cls, raw_model: _ModelType) -> Self:
    """Constructor method to create a new instance from a raw data model class.

    Args:
        raw_model (type): Data model class.

    Returns:
        Self: New instance of ModelInfo.
    """
    get_fields_fn = identify_field_extractor_fn(raw_model)
    if not get_fields_fn:
        raise UnknownModelTypeError(model=raw_model, available_plugins=list_plugins())

    full_name = FullyQualifiedName.from_object(raw_model)
    description = str(full_name)
    docstring = inspect.getdoc(raw_model)
    if docstring:
        description += "\n\n" + docstring + "\n"

    model_info = cls(
        full_name=full_name,
        name=raw_model.__name__,
        fields={field_info.name: field_info for field_info in get_fields_fn(raw_model)},
        description=description,
    )
    model_info._raw_model = raw_model
    return model_info

to_dot_label ¶

to_dot_label() -> str

Returns the DOT language "HTML-like" syntax specification of a table for this data model. It is used as the label attribute of data model's node in the graph's DOT representation.

Returns:

Type	Description
`str`	DOT language for table

Source code in erdantic/core.py

def to_dot_label(self) -> str:
    """Returns the DOT language "HTML-like" syntax specification of a table for this data
    model. It is used as the `label` attribute of data model's node in the graph's DOT
    representation.

    Returns:
        str: DOT language for table
    """
    # Get number of columns dynamically from first row
    num_cols = next(iter(self.fields.values())).to_dot_row().count("<td")
    # Concatenate DOT of all rows together
    rows = "\n".join(field_info.to_dot_row() for field_info in self.fields.values()) + "\n"
    return self._dot_table_template.format(
        name=self.name, num_cols=num_cols, rows=rows
    ).replace("\n", "")

erdantic.core¶

DEFAULT_EDGE_ATTR module-attribute ¶

DEFAULT_GRAPH_ATTR module-attribute ¶

DEFAULT_NODE_ATTR module-attribute ¶

Cardinality ¶

to_dot ¶

Edge ¶

key property ¶

from_field_info classmethod ¶

source_dot_arrow_shape ¶

target_dot_arrow_shape ¶

EntityRelationshipDiagram ¶

add_model ¶

draw ¶

to_dot ¶

to_graphviz ¶

FieldInfo ¶

key property ¶

raw_type property ¶

from_raw_type classmethod ¶

to_dot_row ¶

FullyQualifiedName ¶

from_object classmethod ¶

import_object ¶

Modality ¶

to_dot ¶

ModelInfo ¶

key property ¶

raw_model property ¶

from_raw_model classmethod ¶

to_dot_label ¶

DEFAULT_EDGE_ATTR `module-attribute` ¶

DEFAULT_GRAPH_ATTR `module-attribute` ¶

DEFAULT_NODE_ATTR `module-attribute` ¶

key `property` ¶

from_field_info `classmethod` ¶

key `property` ¶

raw_type `property` ¶

from_raw_type `classmethod` ¶

from_object `classmethod` ¶

key `property` ¶

raw_model `property` ¶

from_raw_model `classmethod` ¶