Fix pydantic dataclass problem with dataclasses.field default (#7898)

pydantic/_internal/_fields.py

@@ -248,7 +248,11 @@ def collect_dataclass_fields(
         if is_classvar(ann_type):
             continue
 
-        if not dataclass_field.init and dataclass_field.default_factory == dataclasses.MISSING:
+        if (
+            not dataclass_field.init
+            and dataclass_field.default == dataclasses.MISSING
+            and dataclass_field.default_factory == dataclasses.MISSING
+        ):
             # TODO: We should probably do something with this so that validate_assignment behaves properly
             #   Issue: https://github.com/pydantic/pydantic/issues/5470
             continue

tests/test_dataclasses.py

@@ -24,6 +24,7 @@
     PydanticDeprecatedSince20,
     PydanticUndefinedAnnotation,
     PydanticUserError,
+    RootModel,
     TypeAdapter,
     ValidationError,
     ValidationInfo,
@@ -2459,7 +2460,21 @@ def test_dataclass_field_default_factory_with_init():
     class Model:
         x: int = dataclasses.field(default_factory=lambda: 3, init=False)
 
-    assert Model().x == 3
+    m = Model()
+    assert 'x' in Model.__pydantic_fields__
+    assert m.x == 3
+    assert RootModel[Model](m).model_dump() == {'x': 3}
+
+
+def test_dataclass_field_default_with_init():
+    @pydantic.dataclasses.dataclass
+    class Model:
+        x: int = dataclasses.field(default=3, init=False)
+
+    m = Model()
+    assert 'x' in Model.__pydantic_fields__
+    assert m.x == 3
+    assert RootModel[Model](m).model_dump() == {'x': 3}
 
 
 def test_metadata():