mirror of https://github.com/scrapy/scrapy.git
131 lines
3.5 KiB
Python
131 lines
3.5 KiB
Python
from __future__ import annotations
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import inspect
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import logging
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from typing import TYPE_CHECKING, Any, TypeVar, overload
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from scrapy.spiders import Spider
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from scrapy.utils.defer import deferred_from_coro
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from scrapy.utils.misc import arg_to_iter
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if TYPE_CHECKING:
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from collections.abc import AsyncGenerator, Iterable
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from types import CoroutineType, ModuleType
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from twisted.internet.defer import Deferred
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from scrapy import Request
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from scrapy.spiderloader import SpiderLoaderProtocol
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logger = logging.getLogger(__name__)
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_T = TypeVar("_T")
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# https://stackoverflow.com/questions/60222982
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@overload
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def iterate_spider_output(result: AsyncGenerator[_T]) -> AsyncGenerator[_T]: ... # type: ignore[overload-overlap]
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@overload
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def iterate_spider_output(result: CoroutineType[Any, Any, _T]) -> Deferred[_T]: ...
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@overload
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def iterate_spider_output(result: _T) -> Iterable[Any]: ...
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def iterate_spider_output(
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result: Any,
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) -> Iterable[Any] | AsyncGenerator[_T] | Deferred[_T]:
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if inspect.isasyncgen(result):
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return result
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d: Deferred[_T] = deferred_from_coro(result)
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if inspect.iscoroutine(result):
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return d.addCallback(iterate_spider_output)
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return arg_to_iter(d)
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def iter_spider_classes(module: ModuleType) -> Iterable[type[Spider]]:
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"""Return an iterator over all spider classes defined in the given module
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that can be instantiated (i.e. which have name)
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"""
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for obj in vars(module).values():
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if (
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inspect.isclass(obj)
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and issubclass(obj, Spider)
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and obj.__module__ == module.__name__
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and getattr(obj, "name", None)
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):
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yield obj
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@overload
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def spidercls_for_request(
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spider_loader: SpiderLoaderProtocol,
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request: Request,
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default_spidercls: type[Spider],
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log_none: bool = ...,
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log_multiple: bool = ...,
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) -> type[Spider]: ...
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@overload
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def spidercls_for_request(
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spider_loader: SpiderLoaderProtocol,
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request: Request,
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default_spidercls: None,
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log_none: bool = ...,
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log_multiple: bool = ...,
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) -> type[Spider] | None: ...
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@overload
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def spidercls_for_request(
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spider_loader: SpiderLoaderProtocol,
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request: Request,
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*,
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log_none: bool = ...,
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log_multiple: bool = ...,
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) -> type[Spider] | None: ...
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def spidercls_for_request(
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spider_loader: SpiderLoaderProtocol,
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request: Request,
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default_spidercls: type[Spider] | None = None,
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log_none: bool = False,
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log_multiple: bool = False,
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) -> type[Spider] | None:
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"""Return a spider class that handles the given Request.
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This will look for the spiders that can handle the given request (using
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the spider loader) and return a Spider class if (and only if) there is
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only one Spider able to handle the Request.
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If multiple spiders (or no spider) are found, it will return the
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default_spidercls passed. It can optionally log if multiple or no spiders
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are found.
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"""
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snames = spider_loader.find_by_request(request)
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if len(snames) == 1:
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return spider_loader.load(snames[0])
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if len(snames) > 1 and log_multiple:
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logger.error(
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"More than one spider can handle: %(request)s - %(snames)s",
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{"request": request, "snames": ", ".join(snames)},
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)
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if len(snames) == 0 and log_none:
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logger.error(
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"Unable to find spider that handles: %(request)s", {"request": request}
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)
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return default_spidercls
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class DefaultSpider(Spider):
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name = "default"
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