Add file/image field

tests/test_fields.py

@@ -16,7 +16,9 @@
     DateTime,
     Decimal,
     Email,
+    File,
     Float,
+    Image,
     Integer,
     IPAddress,
     Number,
@@ -889,3 +891,47 @@ def test_url():
     validator = URL()
     value, error = validator.validate_or_error("example")
     assert error == ValidationError(text="Must be a real URL.", code="invalid")
+
+
+def test_file():
+    validator = File()
+    with open("test.txt", "w") as f:
+        f.write("123")
+    with open("test.txt") as f:
+        value, error = validator.validate_or_error(f)
+        assert value == f
+
+    validator = File()
+    value, error = validator.validate_or_error(None)
+    assert error == ValidationError(text="Must be a file descriptor.", code="type")
+
+
+def test_image():
+    validator = Image(image_types=["png"])
+    with open("test.png", "wb") as f:
+        f.write(b"\211PNG\r\n\032\nxxxxxxxxxxxxxxxxxxxxxxxy")
+
+    with open("test.png", "rb") as f:
+        value, error = validator.validate_or_error(f)
+        assert value == f
+
+    validator = Image(image_types=["png"])
+    value, error = validator.validate_or_error(None)
+    assert error == ValidationError(text="Must be a file descriptor.", code="type")
+
+    with open("test.png", "wb") as f:
+        f.write(b"123")
+
+    with open("test.png", "rb") as f:
+        value, error = validator.validate_or_error(f)
+        assert error == ValidationError(text="Must be a image type.", code="file_type")
+
+    validator = Image(image_types=["jpg"])
+    with open("test.png", "wb") as f:
+        f.write(b"\211PNG\r\n\032\nxxxxxxxxxxxxxxxxxxxxxxxy")
+
+    with open("test.png", "rb") as f:
+        value, error = validator.validate_or_error(f)
+        assert error == ValidationError(
+            text="Did not match the image_types.", code="image_types"
+        )

typesystem/fields.py

@@ -1,4 +1,6 @@
 import decimal
+import imghdr
+import io
 import re
 import typing
 from math import isfinite
@@ -385,7 +387,7 @@ def validate(self, value: typing.Any) -> typing.Any:
             return None
         elif value is None:
             raise self.validation_error("null")
-        elif value not in Uniqueness([key for key, value in self.choices]):
+        elif value not in Uniqueness([key for key, val in self.choices]):
             if value == "":
                 if self.allow_null and self.coerce_types:
                     return None
@@ -749,7 +751,7 @@ def validate(self, value: typing.Any) -> typing.Any:
 
 class Const(Field):
     """
-    Only ever matches the given given value.
+    Only ever matches the given value.
     """
 
     errors = {"only_null": "Must be null.", "const": "Must be the value '{const}'."}
@@ -790,3 +792,47 @@ def __init__(self, **kwargs: typing.Any) -> None:
 class URL(String):
     def __init__(self, **kwargs: typing.Any) -> None:
         super().__init__(format="url", **kwargs)
+
+
+class File(Field):
+    errors = {
+        "type": "Must be a file descriptor.",
+    }
+    value_types = (
+        io.BufferedReader,
+        io.TextIOWrapper,
+        io.BufferedRandom,
+        io.BufferedWriter,
+    )
+
+    def __init__(self, **kwargs: typing.Any) -> None:
+        super().__init__(**kwargs)
+
+    def validate(self, value: typing.Any) -> typing.Any:
+        if not isinstance(value, self.value_types):
+            raise self.validation_error("type")
+        return value
+
+
+class Image(File):
+    errors = {
+        "type": "Must be a file descriptor.",
+        "image_types": "Did not match the image_types.",
+        "file_type": "Must be a image type.",
+    }
+
+    def __init__(
+        self, image_types: typing.List[str] = None, **kwargs: typing.Any
+    ) -> None:
+
+        super().__init__(**kwargs)
+        self.image_types = image_types
+
+    def validate(self, value: typing.Any) -> typing.Any:
+        value = super().validate(value)
+        image_type: typing.Optional[str] = imghdr.what(value)
+        if image_type is None:
+            raise self.validation_error("file_type")
+        if self.image_types is not None and image_type in self.image_types:
+            return value
+        raise self.validation_error("image_types")

typesystem/json_schema.py

@@ -408,15 +408,14 @@ def to_json_schema(
     elif isinstance(arg, NeverMatch):
         return False
 
-    field: typing.Optional[Field]
+    field: typing.Optional[Field] = None
     data: dict = {}
     is_root = _definitions is None
     definitions = {} if _definitions is None else _definitions
 
     if isinstance(arg, Field):
         field = arg
     elif isinstance(arg, Definitions):
-        field = None
         for key, value in arg.items():
             definitions[key] = to_json_schema(value, _definitions=definitions)