add URL field (#117)

docs/fields.md

@@ -94,6 +94,11 @@ Validates IPv4 and IPv6 addresses.
 
 Returns `ipaddress.IPv4Address` or `ipaddress.IPv6Address` based on input.
 
+### URL
+
+Similar to `String` and takes the same arguments.
+Represented in HTML forms as a `<input type="url">`.
+
 ## Boolean data types
 
 ### Boolean

tests/test_fields.py

@@ -6,6 +6,7 @@
 
 from typesystem.base import Message, ValidationError
 from typesystem.fields import (
+    URL,
     UUID,
     Array,
     Boolean,
@@ -878,3 +879,13 @@ def test_ipaddress():
         "2001:0dz8:85a3:0000:0000:8a2e:0370:7334"
     )
     assert error == ValidationError(text="Must be a valid IP format.", code="format")
+
+
+def test_url():
+    validator = URL()
+    value, error = validator.validate_or_error("https://example.com")
+    assert value == "https://example.com"
+
+    validator = URL()
+    value, error = validator.validate_or_error("example")
+    assert error == ValidationError(text="Must be a real URL.", code="invalid")

tests/test_forms.py

@@ -15,6 +15,7 @@
         "extra": typesystem.Boolean(default=True, read_only=True),
         "email": typesystem.Email(),
         "password": typesystem.Password(),
+        "url": typesystem.URL(),
     }
 )
 
@@ -33,6 +34,7 @@ def test_form_rendering():
     assert html.count("<select ") == 1
     assert html.count('<input type="email" ') == 1
     assert html.count('<input type="password" ') == 1
+    assert html.count('<input type="url" ') == 1
 
 
 def test_password_rendering():

tests/test_schemas.py

@@ -530,3 +530,14 @@ def test_schema_ipaddress_serialization():
     data = schema.serialize(item)
     assert data["src"] == "127.0.0.1"
     assert data["dst"] is None
+
+
+def test_schema_url_serialization():
+    schema = typesystem.Schema(
+        fields={"url": typesystem.URL(), "website": typesystem.URL()}
+    )
+
+    item = {"url": "https://google.com", "website": None}
+    data = schema.serialize(item)
+    assert data["url"] == "https://google.com"
+    assert data["website"] is None

typesystem/__init__.py

@@ -1,5 +1,6 @@
 from typesystem.base import Message, ParseError, Position, ValidationError
 from typesystem.fields import (
+    URL,
     UUID,
     Any,
     Array,
@@ -51,6 +52,7 @@
     "Text",
     "Time",
     "Union",
+    "URL",
     "UUID",
     # Schemas
     "Schema",

typesystem/fields.py

@@ -16,6 +16,7 @@
     "uuid": formats.UUIDFormat(),
     "email": formats.EmailFormat(),
     "ipaddress": formats.IPAddressFormat(),
+    "url": formats.URLFormat(),
 }
 
 
@@ -784,3 +785,8 @@ def __init__(self, **kwargs: typing.Any) -> None:
 class IPAddress(String):
     def __init__(self, **kwargs: typing.Any) -> None:
         super().__init__(format="ipaddress", **kwargs)
+
+
+class URL(String):
+    def __init__(self, **kwargs: typing.Any) -> None:
+        super().__init__(format="url", **kwargs)

typesystem/formats.py

@@ -3,6 +3,7 @@
 import re
 import typing
 import uuid
+from urllib.parse import urlparse
 
 from typesystem.base import ValidationError
 
@@ -244,3 +245,23 @@ def serialize(
         assert isinstance(obj, (ipaddress.IPv4Address, ipaddress.IPv6Address))
 
         return str(obj)
+
+
+class URLFormat(BaseFormat):
+    errors = {"invalid": "Must be a real URL."}
+
+    def is_native_type(self, value: typing.Any) -> bool:
+        return False
+
+    def validate(self, value: typing.Any) -> str:
+        url = urlparse(value)
+        if not all([url.scheme, url.netloc]):
+            raise self.validation_error("invalid")
+
+        return str(value)
+
+    def serialize(self, obj: typing.Optional[str]) -> typing.Optional[str]:
+        if obj is None:
+            return None
+
+        return obj