MongoDb 试图对嵌入文档进行计数

Question

I have a document which looks like this

{'name':'abc',
'location': 'xyz',
 'social_links' : { 'facebook' : 'links',
                     'Whosebug': 'links',
                     'quora' : 'links' ... }
}

I want to count the total number of links for each social_links in my collection Currently my code looks like this

    db.main_candidate.aggregate( [  { '$match': {'social_links.quora':     {'$exists': true}}},  {'$group': { '_id' :'quora', 'count': {'$sum':1 }}}])

While this is correctly returning the counts for the specific social_link, I want to write a query which will be able to count for all the social_links in a single query instead of having to write for each specific name.

Answer 1

我认为如果不对特定名称进行硬编码，就无法通过查询对您想要的内容进行分组。也许您应该尝试使用 MapReduce。

您应该将 social_links 存储为数组而不是文档，这对我来说更有意义。类似于：

{'name':'abc',
'location': 'xyz',
 'social_links' : [ { 'name':'facebook', 'link' : 'links'},
                    { 'name':'quora', 'link' : 'links'},
                    { 'name':'Whosebug', 'link' : 'links'}]
}

那么你可以进行如下查询：

db.col.aggregate(
{
 $unwind: "$social_links"
},
{
 $group: 
 {
   _id: "$social_links.name",
   count: $sum: 1
  }
})

MongoDb 试图对嵌入文档进行计数

MongoDb trying to count inside embedded documents

count

mongodb

mongodb-query

aggregation-framework