pydantic-string-url

Pydantic URL types that are based on the str class.

Introduction

Since Pydantic v2 the types realated to URLs are not based on the standard Python str class any more.

This decision comes with some issues:

• URLs cannot be directly passed to library packages that expect str, you must use str(url) instead
• some internal normalization is done, so the input strings are not always preserved when a URL object is created (trailing slashes could be added), which might be problematic for some applications

This package provides direct replacements for the Pydantic types:

• AnyUrl
• AnyHttpUrl
• HttpUrl
• AnyWebsocketUrl
• WebsocketUrl
• FileUrl
• FtpUrl

Those replacement types are based on strings, so they are also a str, preserve the original input string and use the same validation functions as their Pydantic counterparts. You can still use the replacement type's .url property to access the original Pydantic URL type.

See also the discussions here:

• AnyUrl adds trailing slash
• Work around for pydantic_core._pydantic_core.Url in V2 where string is expected
• How can I integrate pydantic v2 URLs in code?
• Url and Dsn types in pydantic.networks no longer inherit from str

Usage

The package pydantic-string-url is available on PyPi, so it can be installed with Python package managers such as pip or poetry.

Usage example:

"""Example."""

from pydantic import BaseModel, TypeAdapter, ValidationError

from pydantic_string_url import HttpUrl


# Use inside BaseModel
class User(BaseModel):
    """A user."""

    name: str
    age: int
    homepage: HttpUrl


user = {"name": "John Doe", "age": 33, "homepage": "https://example.com"}

invalid_user = {"name": "Alice", "age": 32, "homepage": "not a url"}

john = User.model_validate(user)
assert john.homepage == "https://example.com"  # no trailing slash was added
try:
    alice = User.model_validate(invalid_user)
except ValidationError as e:
    print(str(e))

# Use standalone
urls = ["https://test.com", "some wrong url"]

url_a = TypeAdapter(HttpUrl).validate_python(urls[0])
try:
    url_b = TypeAdapter(HttpUrl).validate_python(urls[1])
except ValidationError as e:
    print(str(e))

# You can still access the Pydantic type by using the string's .url property
assert url_a.url.scheme == "https"
assert john.homepage.url.scheme == "https"

Licence

MIT