support for tuple or dict in dataclasses

pydantic · samuelcolvin · Dec 27, 2018 · Dec 27, 2018 · Dec 27, 2018 · Dec 27, 2018
commit 70a73d5ecff3e65bdcd4e26c639a6508a70cade9
diff --git a/HISTORY.rst b/HISTORY.rst
@@ -12,6 +12,7 @@ v0.17.0 (unreleased)
 * fix schema generation for fields annotated as ``: dict``, #330 by @nkonin
 * support for passing Config class in dataclasses decorator, #276 by @jarekkar
   (**breaking change**: this supersedes the ``validate_assignment`` argument with ``config``)
+* support for nested dataclasses, #334 by @samuelcolvin
 
 v0.16.1 (2018-12-10)
 ....................

diff --git a/pydantic/dataclasses.py b/pydantic/dataclasses.py
@@ -16,6 +16,10 @@ def _get_validators(cls):
     def _validate_dataclass(v):
         if isinstance(v, cls):
             return v
+        elif isinstance(v, (cls, list, tuple)):
+            return cls(*v)
+        elif isinstance(v, dict):
+            return cls(**v)
         else:
             raise errors.DataclassTypeError(class_name=cls.__name__)
 

diff --git a/pydantic/errors.py b/pydantic/errors.py
@@ -270,4 +270,4 @@ class PatternError(PydanticValueError):
 
 class DataclassTypeError(PydanticTypeError):
     code = 'dataclass'
-    msg_template = 'must be an instance of {class_name}'
+    msg_template = 'instance of {class_name}, tuple or dict expected'
diff --git a/tests/test_dataclasses.py b/tests/test_dataclasses.py
@@ -1,11 +1,9 @@
+import dataclasses
+
 import pytest
 
 import pydantic
-<<<<<<< HEAD
-from pydantic import BaseConfig, ValidationError
-=======
 from pydantic import BaseModel, ValidationError
->>>>>>> dataclass validation, fix #273
 
 
 def test_simple():
@@ -159,7 +157,7 @@ class MyDataclass:
     with pytest.raises(ValidationError) as exc_info:
         d.a = 'xxxx'
 
-    assert issubclass(MyDataclass.__pydantic_model__.__config__, BaseConfig)
+    assert issubclass(MyDataclass.__pydantic_model__.__config__, BaseModel.Config)
     assert exc_info.value.errors() == [
         {
             'loc': ('a',),
@@ -185,26 +183,66 @@ class MyDataclass:
     assert d.a == 'xxxx'
 
 
-def test_dataclass_subtype():
+def test_nested_dataclass():
     @pydantic.dataclasses.dataclass
+    class Nested:
+        number: int
+
+    class Outer(BaseModel):
+        n: Nested
+
+    navbar = Outer(n=Nested(number='1'))
+    assert isinstance(navbar.n, Nested)
+    assert navbar.n.number == 1
+
+    navbar = Outer(n=('2',))
+    assert isinstance(navbar.n, Nested)
+    assert navbar.n.number == 2
+
+    navbar = Outer(n={'number': '3'})
+    assert isinstance(navbar.n, Nested)
+    assert navbar.n.number == 3
+
+    with pytest.raises(ValidationError) as exc_info:
+        Outer(n='not nested')
+    assert exc_info.value.errors() == [
+        {
+            'loc': ('n',),
+            'msg': 'instance of Nested, tuple or dict expected',
+            'type': 'type_error.dataclass',
+            'ctx': {'class_name': 'Nested'},
+        }
+    ]
+
+    with pytest.raises(ValidationError) as exc_info:
+        Outer(n=('x',))
+    assert exc_info.value.errors() == [
+        {'loc': ('n', 'number'), 'msg': 'value is not a valid integer', 'type': 'type_error.integer'}
+    ]
+
+
+def test_arbitrary_types_allowed():
+    @dataclasses.dataclass
     class Button:
         href: str
 
     class Navbar(BaseModel):
         button: Button
 
+        class Config:
+            arbitrary_types_allowed = True
+
     btn = Button(href='a')
     navbar = Navbar(button=btn)
-    assert isinstance(navbar.button, Button)
     assert navbar.button.href == 'a'
 
     with pytest.raises(ValidationError) as exc_info:
-        Navbar(button='not button')
+        Navbar(button=('b',))
     assert exc_info.value.errors() == [
         {
-            'ctx': {'class_name': 'Button'},
             'loc': ('button',),
-            'msg': 'must be an instance of Button',
-            'type': 'type_error.dataclass',
+            'msg': 'instance of Button expected',
+            'type': 'type_error.arbitrary_type',
+            'ctx': {'expected_arbitrary_type': 'Button'},
         }
     ]