Question

我有一个这样的收藏集D1：

{
   _id: 0,
   author:Jose Fernandez,
   handle: Md8937,
   reference: [
     { item_id: 43, author: Alberto Perez, year: 1910, context: some text },

     { item_id: 44, author: Lucas Leys, year: 1990, context: some text },

     { item_id: 45, author: Johan Ortiz, year: 2005}
   ]
}
{
   _id: 1,
   author: Ramiro Ramirez,
   handle: Gh8765,
   reference: [
     { item_id: 68, author: Mats Valk, year: 1993, context: some text },

     { item_id: 74, author: Robert Lucas, year: 1976, context: some text },

     { item_id: 80, author: Mark Ljumberg, year: 2005, context: some text}
   ]
}
{
   _id: 2,
   author: Feliks Zemdges,
   handle: Yt4573,
   reference: [
     { item_id: 1, author: Gan Zandhi, year: 2015},

     { item_id: 2, author: Dayan Wojung, year: 1976, context: some text },

   ]
}

我需要从其中创建一个python列表，其中包含集合中每个对象的所有handle值，如下所示：

handles=["Md8937","Gh8765","Yt4573"]

我该怎么办？

Answer 1

创建一个游标并根据需要附加每个项目。

import pymongo

db = pymongo.MongoClient(")['mydatabase']

cursor = db.mycollection.find({}, {'handle': 1, '_id': 0})
handles = []
for item in cursor:
    if 'handle' in item:
        handles.append(item['handle'])

print (handles)

Answer 2

如果handle的值是唯一的（并且您的集合不是很大），您还可以使用：

from pymongo import MongoClient
CON = MongoClient()
db = CON['YourDatabase']      
coll = db['YourCollection']
handles = coll.distinct('handle')

从MongoDB集合中的一组文档中列出一个清单

2 个答案: