在構(gòu)造Request時，meta參數(shù)可以作為參數(shù)傳遞的載體，meta內(nèi)容并不會提交到請求中。
例如：

In [1]: fetch(scrapy.Request('http://httpbin.org/get',meta={'name':'張三'}))
In [2]: response.text
Out[2]: '{"args":{},"headers":{"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8","Accept-Encoding":"gzip,deflate","Accept-Language":"en","Connection":"close","Host":"httpbin.org","User-Agent":"Baiduspider"},"origin":"180.169.75.62","url":"http://httpbin.org/get"}\n'
In [5]: response.meta['name']
Out[5]: '張三'