[WIP] use response selector cache #3157
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Codecov Report
@@ Coverage Diff @@
## master #3157 +/- ##
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+ Coverage 82.11% 82.11% +<.01%
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Files 228 228
Lines 9588 9589 +1
Branches 1385 1385
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+ Hits 7873 7874 +1
Misses 1456 1456
Partials 259 259
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kmike
requested changes
Mar 10, 2018
scrapy/loader/__init__.py
Outdated
| @@ -26,7 +26,10 @@ class ItemLoader(object): | |||
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| def __init__(self, item=None, selector=None, response=None, parent=None, **context): | |||
| if selector is None and response is not None: | |||
| selector = self.default_selector_class(response) | |||
| if response.selector.__class__ == Selector: | |||
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Hi @nctl144,
There are two issues with this line:
- If a subclass overrides
default_selector_classattribute, it won't have an effect after this change. - As I mentioned in https://github.com/scrapy/scrapy/issues/3125#issuecomment-366316774, this approach has an issue: when someone accesses
response.selectorfirst time, Scrapy parses response body; when this condition is False, we'd be parsing response body twice (here + later, atself.default_selector_class(response)line). This looks unnecesary.
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Hey @kmike , I got what you mean. So I modified the code so that we use the response.selector even when the response._cached_selector is None. Since response.selector returns a new Selector object (of the current response) when the selector has no cache, I think the code is still the same right? |
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Use response selector cache instead of creating new one every time an ItemLoader object is created. As mentioned in issue #3125. I created this as a sample code to continue the discussion :)