python ijson大文件循环来获取名称

Question

我需要使用ijson解析一个大的json文件（除非有更好的办法），我想遍历请求中的所有产品名称并打印出来。我试图用这个支持页面来设置它。 https://pypi.python.org/pypi/ijson/

这是电流输出，我得到

<addinfourl at 140643118020800 whose fp = <socket._fileobject object at 0x7fea07882850>> 
<generator object items at 0x7fea077dc910> 
<generator object <genexpr> at 0x7fea077dc960> 

我的代码

import json 
import requests 
import lxml 
import ijson 
import urllib 
from urllib import urlopen 


request = urlopen('www.jsonurl.com') 
objects = ijson.items(request, 'items.name') 
products = (o for o in objects if o ['type' == 'name']) 
for product in products: 
    print product 

print request 
print objects 
print products 

这里是一块JSON数据

{"query":"*","sort":"relevance","responseGroup":"base","totalResults":5158058,"start":1,"numItems":10,"items":[{"itemId":7933617,"parentItemId":7933617,"name":"Nordic Ware Heavyweight Scone/Cornbread Pan","msrp":26.97,"salePrice":20.42,"upc":"011172016409","categoryPath":"Home/Kitchen & Dining/Cookware, Bakeware & Tools/Specialty Cookware","shortDescription":"<p>This Nordic Ware Scone Pan is made of a heavyweight cast aluminum. It can be used as a heavyweight scone or cornbread pan, and it is designed to cook your meal evenly and thoroughly. It features a non-stick interior coating for easy release and clean up.</p>","longDescription":"<b>Nordic Ware Heavyweight Scone/Cornbread Pan:</b><ul><li>Heavyweight cast aluminum</li><li>Ideal for scones and cornbread</li><li>Eight wedges</li><li>Cooks evenly and thoroughly</li><li>Non-stick interior coating for easy release and clean-up</li></ul>","thumbnailImage":"http://i5.walmartimages.com/dfw/dce07b8c-c739/k2-_6fb32a28-c090-4377-81d5-e83273124841.v1.jpg","mediumImage":"http://i5.walmartimages.com/dfw/dce07b8c-ddb3/k2-_6f7df9fa-cb2d-4faf-afbc-8fa4185add59.v1.jpg","largeImage":"http://i5.walmartimages.com/dfw/dce07b8c-5bd3/k2-_6635f62a-5e0b-4c4e-a93d-ee85643f7397.v1.jpg","productTrackingUrl":"http://linksynergy.walmart.com/fs-bin/click?id=|LSNID|&offerid=223073.7200&type=14&catid=8&subid=0&hid=7200&tmpid=1082&RD_PARM1=http%253A%252F%252Fwww.walmart.com%252Fip%252FNordicWare-Heavyweight-Scone-Cornbread-Pan%252F7933617%253Faffp1%253DpjiPu5Y7cvNmz4xZOAs5j7QlW2mZPVmc1DR3BvmrkB4%2526affilsrc%253Dapi","standardShipRate":4.97,"marketplace":false,"modelNumber":"1640","productUrl":"http://c.affil.walmart.com/t/api02?l=http%3A%2F%2Fwww.walmart.com%2Fip%2FNordicWare-Heavyweight-Scone-Cornbread-Pan%2F7933617%3Faffp1%3DpjiPu5Y7cvNmz4xZOAs5j7QlW2mZPVmc1DR3BvmrkB4%26affilsrc%3Dapi%26veh%3Daff%26wmlspartner%3Dreadonlyapi","customerRating":"4.7","numReviews":20,"customerRatingImage":"http://i2.walmartimages.com/i/CustRating/4_7.gif","categoryNode":"4044_623679_133020","bundle":false,"stock":"Available","addToCartUrl":"http://c.affil.walmart.com/t/api02?l=http%3A%2F%2Faffil.walmart.com%2Fcart%2FaddToCart%3Fitems%3D7933617%7C1%26affp1%3DpjiPu5Y7cvNmz4xZOAs5j7QlW2mZPVmc1DR3BvmrkB4%26affilsrc%3Dapi%26veh%3Daff%26wmlspartner%3Dreadonlyapi","affiliateAddToCartUrl":"http://linksynergy.walmart.com/fs-bin/click?id=|LSNID|&offerid=223073.7200&type=14&catid=8&subid=0&hid=7200&tmpid=1082&RD_PARM1=http%253A%252F%252Faffil.walmart.com%252Fcart%252FaddToCart%253Fitems%253D7933617%257C1%2526affp1%253DpjiPu5Y7cvNmz4xZOAs5j7QlW2mZPVmc1DR3BvmrkB4%2526affilsrc%253Dapi","giftOptions": 

Answer 1

您在我们的输出中看到什么是：

print request：打开连接到一个URL - 这似乎是正确的，而不是令人惊讶

print objects：作为输出告诉，这是一个发生，你可能会想到 值的列表。但由于对象实际上是一个生成器（您通过使用ijson提出要求），您应该从中消耗这些值。典型的你通过list(objects)

print products：也是一个生成器，但这次是列表理解的结果。由于您在表达式的周围使用了() ，因此您需要一个生成器。如果你使用[o for o in objects if o ['type' == 'name']]，你会直接得到清单。解决方案与objects一样：消耗 值，例如，通过list(products)。

请注意，一旦您从生成器中消耗了一个值（或全部值），它们就会消失，因为 生成器保持其私有内部状态，每次调用都会改变它的私有内部状态。

欲了解更多信息，请参阅SO问题Convert generator object to list for debugging。