MongoDB内嵌文档查询

MongoDB内嵌文档查询

1. 示例数据结构

 [{"name": "lisa", "age": 17,
              "friends": [{"name": "tom", "tel": "17876353434"}, {"name": "bob", "tel": "17876753434"}]},
             {"name": "anna", "age": 17,
              "friends": [{"name": "tony", "tel": "17876358434"}, {"name": "ming", "tel": "17876753434"}]}]

2. 查询
   一般在查询时，只针对内嵌文档的特定键值去查询，可以使用"."来表示进入内嵌文档。

查询friends中name为tom的信息：

query_dict = {"friends.name": "tom"}
result=mycol.find_one(query_dict)

结果如下：
{’_id’: ObjectId(‘6099fe790abc10d0ffd5532b’), ‘name’: ‘lisa’, ‘age’: 17, ‘friends’: [{‘name’: ‘tom’, ‘tel’: ‘17876353434’}, {‘name’: ‘bob’, ‘tel’: ‘17876753434’}]}

3. 取消查询结果中的"_id"列

query_dict = {"friends.name": "tom"}
result=mycol.find_one(query_dict, {"_id": 0})

结果如下：
{‘name’: ‘lisa’, ‘age’: 17, ‘friends’: [{‘name’: ‘tom’, ‘tel’: ‘17876353434’}, {‘name’: ‘bob’, ‘tel’: ‘17876753434’}]}
另，如果想取消查询friends里的tel列，则代码如下：

query_dict = {"friends.name": "tom"}
result=mycol.find_one(query_dict, {"friends.tel": 0})

4.完整实例代码如下（python）

import pymongo

myclient = pymongo.MongoClient("mongodb://这里记得改地址噢/")
mydb = myclient["test_db"]  # 数据库
mycol = mydb["test_col"]  # 集合

test_data = [{"name": "lisa", "age": 17,
              "friends": [{"name": "tom", "tel": "17876353434"}, {"name": "bob", "tel": "17876753434"}]},
             {"name": "anna", "age": 17,
              "friends": [{"name": "tony", "tel": "17876358434"}, {"name": "ming", "tel": "17876753434"}]}]

# mycol.insert_many(test_data)  # 将test_data存入集合中

query_dict = {"friends.name": "tom"}
result1=mycol.find_one(query_dict, {"friends.tel": 0})
result2=mycol.find_one(query_dict, {"_id":0,"friends.tel": 0})
print(result2)