Fix error for typing special forms (#115)

* Add test to get_recursive_args for TypeVar

* Fix error for typing special forms

---------

Co-authored-by: Jay Qi <[email protected]>

erdantic/core.py

@@ -513,7 +513,14 @@ def _edge_cls(self) -> Type[Edge]:
 
     def _add_if_model(self, model: type, recurse: bool) -> bool:
         """Private recursive method to add a model to the diagram."""
-        key = str(FullyQualifiedName.from_object(model))
+        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)

tests/test_core.py

@@ -4,14 +4,15 @@
 import os
 from pathlib import Path
 import sys
-from typing import List, Optional
+from typing import Any, AnyStr, List, Literal, Optional, TypeVar
 
 if sys.version_info >= (3, 9):
     from typing import Annotated
 else:
     from typing_extensions import Annotated
 
 import IPython.lib.pretty as IPython_pretty
+import pydantic
 import pytest
 import rich
 
@@ -172,6 +173,21 @@ class NotAModel: ...
         diagram.add_model(NotAModel)
 
 
+def test_model_with_typing_special_forms():
+    """Models may have special forms in the leaf nodes and we should handle it."""
+
+    T = TypeVar("T")
+
+    class MyModel(pydantic.BaseModel):
+        any_field: Any
+        literal_field: Literal["a", "b", "c"]
+        type_var_field: T
+        anystr_field: AnyStr
+
+    diagram = EntityRelationshipDiagram()
+    diagram.add_model(MyModel)
+
+
 def test_unsupported_forward_ref_resolution(monkeypatch):
     """Plugin implementation does not do anything to resolve forward references."""
 

tests/test_typing_utils.py

@@ -48,6 +48,9 @@ def test_get_recursive_args():
         typing.Literal["batman"],
     ]
 
+    T = typing.TypeVar("T")
+    assert get_recursive_args(typing.Union[int, typing.List[T]]) == [int, T]
+
     class SomeForwardRef: ...
 
     with pytest.raises(_UnevaluatedForwardRefError):