python - Scrapy middleware order -

python - Scrapy middleware order -

scrapy documentation says :

the first middleware 1 closer engine , lastly 1 closer downloader.

to decide order assign middleware see downloader_middlewares_base setting , pick value according want insert middleware. order matter because each middleware performs different action , middleware depend on previous (or subsequent) middleware beingness applied

i'm not exclusively clear whether higher value result in middleware getting executed first or vice versa.

e.g.

'myproject.middlewares.mw1': 543, 'myproject.middlewares.mw2': 542,

question :

which of these executed first? trial says mw2 first. what's valid range orders ? 0 - 999 ?

which of these executed first? trial says mw2 first.

as quoted docs:

the first middleware 1 closer engine , lastly 1 closer downloader.

so downloader middleware value of 542 executed before middleware value 543. means first myproject.middlewares.mw1.process_request(request, spider) called, , after altered (if needed) request, passed next downloader middleware.

what's valid range orders ? 0 - 999 ?

the value integer.

update:

look @ architecture.

also, total quote:

the downloader_middlewares setting merged downloader_middlewares_base setting defined in scrapy (and not meant overridden) , sorted order final sorted list of enabled middlewares: first middleware 1 closer engine , lastly 1 closer downloader.

so, values integers, have range of python integers.

python middleware scrapy