如何在剪贴中实现嵌套项?

I am scraping some data with complex hierarchical info and need to export the result to json.

我正在抓取一些具有复杂层次信息的数据，需要将结果导出到json。

I defined the items as

我将项定义为

class FamilyItem():
    name = Field()
    sons = Field()

class SonsItem():
    name = Field()
    grandsons = Field()

class GrandsonsItem():
    name = Field()
    age = Field()
    weight = Field()
    sex = Field()

and when the spider runs complete, I will get a printed item output like

当爬行器运行完成时，我将得到一个打印的项目输出，比如

{'name': 'Jenny',
   'sons': [
            {'name': u'S1',
             'grandsons': [
                   {'name': u'GS1',
                    'age': 18,
                    'weight': 50
                   },
                   {
                    'name':u'GS2',
                    'age': 19,
                    'weight':51}]
                   }]
}

but when I run scrapy crawl myscaper -o a.json, it always says the result "is not JSON serializable". Then I copy and paste the item output into ipython console and use json.dumps(), it works fine.So where is the problem? this is driving my nuts...

但是当我跑的时候，我爬的是我的。json总是说结果“不是json可序列化的”。然后我将项目输出复制并粘贴到ipython控制台并使用json.dumps()，它工作得很好。那么问题在哪呢?这真让我抓狂……

2 个解决方案

#1

When saving the nested items, make sure to wrap them in a call to dict(), e.g.:

保存嵌套项时，请确保将它们包装在对dict()的调用中，例如:

gs1 = GrandsonsItem()
gs1['name'] = 'GS1'
gs1['age'] = 18
gs1['weight'] = 50

gs2 = GrandsonsItem()
gs2['name'] = 'GS2'
gs2['age'] = 19
gs2['weight'] = 51

s1 = SonsItem()
s1['name'] = 'S1'
s1['grandsons'] = [dict(gs1), dict(gs2)]

jenny = FamilyItem()
jenny['name'] = 'Jenny'
jenny['sons'] = [dict(s1)]

#2

Not sure if there's a way to do nested items in scrappy with classes but arrays work fine. You could do something like this:

不确定是否有一种方法可以用类在scrappy中处理嵌套项，但是数组可以很好地工作。你可以这样做:

grandson['name'] = 'Grandson'
grandson['age'] = 2
gransons.append(grandson)
son['name'] = 'Son'
sons['grandson'] = grandsons
sons.append(son)
item.name = 'Name'
item.son = sons

#1