pythonnative/src/pythonnative/net.py at v0.43.1 · pythonnative/pythonnative · GitHub

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"""Async HTTP client (``pn.fetch``).

A small, dependency-free coroutine wrapper around

:mod:`urllib.request`. Operates on bytes internally and exposes a

:class:`Response` with `text()`, `json()`, and `bytes` accessors.

The implementation is deliberately minimal; it covers the

"call a JSON API" path that's overwhelmingly the use case for mobile

apps. For streaming, multipart uploads, or HTTP/2, integrate

``httpx`` / ``aiohttp`` directly; this module won't try to compete.

Example:

```python

import pythonnative as pn

async def load_user(user_id):

resp = await pn.fetch(

f"https://api.example.com/users/{user_id}",

headers={"Accept": "application/json"},

)

resp.raise_for_status()

return resp.json()

```

"""

from __future__ import annotations

import asyncio

import json

import ssl

import urllib.error

import urllib.parse

import urllib.request

from dataclasses import dataclass, field

from typing import Any, Dict, Mapping, Optional, Union

# A package-level SSL context lets callers (or tests) override TLS

# verification globally without monkeypatching the stdlib. Defaults

# to the system trust store.

_default_ssl_context: Optional[ssl.SSLContext] = None

def set_default_ssl_context(context: Optional[ssl.SSLContext]) -> None:

"""Override the SSL context used by [`fetch`][pythonnative.fetch].

``None`` (the default) means ``urllib`` builds a context from

the system trust store. Tests can pass an unverified context.

"""

global _default_ssl_context

_default_ssl_context = context

# ======================================================================

# Response object

# ======================================================================

@dataclass

class Response:

"""The result of a [`fetch`][pythonnative.fetch] call.

Attributes:

status: HTTP status code (e.g. ``200``).

url: Final URL after any redirects.

headers: Response headers, case-insensitive.

content: Raw response body.

"""

status: int

url: str

headers: Mapping[str, str] = field(default_factory=dict)

content: bytes = b""

@property

def ok(self) -> bool:

"""``True`` if the status is in the 2xx range."""

return 200 <= self.status < 300

def __repr__(self) -> str:

cls = type(self).__name__

return f"{cls}(status={self.status}, url={self.url!r}, ok={self.ok}, content={len(self.content)} bytes)"

def text(self, encoding: Optional[str] = None) -> str:

"""Decode ``content`` to ``str``.

Args:

encoding: Optional override; defaults to the

``charset`` parameter of ``Content-Type`` (or UTF-8).

"""

enc = encoding or _charset_from_headers(self.headers) or "utf-8"

try:

return self.content.decode(enc)

except (UnicodeDecodeError, LookupError):

return self.content.decode("utf-8", errors="replace")

def json(self) -> Any:

"""Parse the response body as JSON.

Raises:

json.JSONDecodeError: If the body isn't valid JSON.

"""

return json.loads(self.text())

def raise_for_status(self) -> None:

"""Raise [`HTTPError`][pythonnative.net.HTTPError] for non-2xx responses."""

if not self.ok:

raise HTTPError(self.status, self.url, self.text())

class HTTPError(Exception):

"""Raised by [`Response.raise_for_status`][pythonnative.net.Response.raise_for_status]."""

def __init__(self, status: int, url: str, body: str) -> None:

super().__init__(f"HTTP {status} from {url}: {body[:200]}")

self.status = status

self.url = url

self.body = body

def _charset_from_headers(headers: Mapping[str, str]) -> Optional[str]:

ctype = headers.get("Content-Type") or headers.get("content-type")

if not ctype:

return None

for part in ctype.split(";"):

part = part.strip()

if part.lower().startswith("charset="):

return part[len("charset=") :].strip().strip('"')

return None

# ======================================================================

# Public fetch coroutine

# ======================================================================

async def fetch(

url: str,

method: str = "GET",

headers: Optional[Mapping[str, str]] = None,

body: Union[bytes, str, Mapping[str, Any], None] = None,

params: Optional[Mapping[str, Any]] = None,

timeout: float = 30.0,

) -> Response:

"""Make an HTTP request and return a [`Response`][pythonnative.net.Response].

Args:

url: Target URL. Relative URLs are not supported.

method: HTTP method (``GET``, ``POST``, ``PUT`` …).

headers: Optional request headers.

body: Request body. ``bytes`` are sent as-is; ``str`` is

UTF-8 encoded; ``dict`` is JSON-encoded with a

``Content-Type: application/json`` header added (unless

already supplied).

params: Optional mapping of query-string parameters appended

to ``url`` (urlencoded).

timeout: Seconds to wait for the response (excluding the

time spent on DNS / connect).

Returns:

A [`Response`][pythonnative.net.Response].

Raises:

TimeoutError: If the request doesn't complete within

``timeout`` seconds.

OSError: For network errors (DNS failure, connection refused,

etc.), re-raised from ``urllib``.

Example:

```python

resp = await pn.fetch(

"https://api.example.com/posts",

method="POST",

body={"title": "Hello"},

)

resp.raise_for_status()

```

"""

request = _build_request(url=url, method=method, headers=headers, body=body, params=params)

return await asyncio.to_thread(_dispatch_request, request, timeout)

def _build_request(

url: str,

method: str,

headers: Optional[Mapping[str, str]],

body: Union[bytes, str, Mapping[str, Any], None],

params: Optional[Mapping[str, Any]],

) -> urllib.request.Request:

if params:

sep = "&" if "?" in url else "?"

url = url + sep + urllib.parse.urlencode(params, doseq=True)

header_dict: Dict[str, str] = dict(headers or {})

payload: Optional[bytes] = None

if body is None:

pass

elif isinstance(body, (bytes, bytearray)):

payload = bytes(body)

elif isinstance(body, str):

payload = body.encode("utf-8")

elif isinstance(body, Mapping):

payload = json.dumps(body, default=str).encode("utf-8")

if not any(name.lower() == "content-type" for name in header_dict):

header_dict["Content-Type"] = "application/json"

else:

raise TypeError(f"Unsupported body type: {type(body)!r}")

return urllib.request.Request(

url=url,

data=payload,

method=method.upper(),

headers=header_dict,

)

def _dispatch_request(request: urllib.request.Request, timeout: float) -> Response:

context = _default_ssl_context

try:

with urllib.request.urlopen(request, timeout=timeout, context=context) as resp:

content = resp.read()

return Response(

status=resp.status,

url=resp.geturl(),

headers={k: v for k, v in resp.headers.items()},

content=content,

)

except urllib.error.HTTPError as exc:

# HTTPError is itself a response object; propagate the body

# so callers can inspect it before deciding to raise.

body = exc.read() if hasattr(exc, "read") else b""

return Response(

status=exc.code,

url=getattr(exc, "url", request.full_url),

headers={k: v for k, v in (exc.headers or {}).items()},

content=body,

)

except urllib.error.URLError as exc:

# Convert urllib's TimeoutError wrapper into a plain TimeoutError

# so callers get a recognisable exception type.

reason = getattr(exc, "reason", exc)

if isinstance(reason, TimeoutError):

raise reason

raise OSError(str(reason)) from exc

__all__ = ["fetch", "Response", "HTTPError", "set_default_ssl_context"]

pythonnative/src/pythonnative/net.py at v0.43.1 · pythonnative/pythonnative · GitHub

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