Python MongoDB – find_one_and_update 查询

函数find_one_and_update()实际上是查找并更新一个 MongoDB 文档。尽管默认情况下，此函数以原始形式返回文档，并且返回更新后的文档return_document必须在代码中实现。

Syntax: coll.find_one_and_update(filter, update, options)

Parameters:

• col- collection in MongoDB
• filter- criteria to find the document which needs to be updated
• update- The operations which need to be implemented for updating the document
• options- projection or upsert can be used here
• projection- a mapping which informs about which fields are included and excluded, it is 1/TRUE for including a field and 0/FALSE for excluding
• upsert- for inserting a new document if no file is found with the mentioned criteria upsert is TRUE

示例 1：

样本数据库：

from pymongo import MongoClient
from pymongo import ReturnDocument
  
  
# Create a pymongo client
client = MongoClient('localhost', 27017)
  
# Get the database instance
db = client['GFG']
  
# Create a collection
doc = db['Student']
  
print(doc.find_one_and_update({'name':"Raju"},
                        { '$set': { "Branch" : 'ECE'} }, 
                        return_document = ReturnDocument.AFTER))

输出：

{‘_id’: 5, ‘name’: ‘Raju’, ‘Roll No’: ‘1005’, ‘Branch’: ‘ECE’}

示例 2：

from pymongo import MongoClient
from pymongo import ReturnDocument
  
  
# Create a pymongo client
client = MongoClient('localhost', 27017)
  
# Get the database instance
db = client['GFG']
  
# Create a collection
doc = db['Student']
  
print(# Increasing marks of Ravi by 10 
doc.find_one_and_update({'name': "Raju"}, 
                        { '$set': { "Branch" : 'CSE'} }, 
                        projection = { "name" : 1, "Branch" : 1 }, 
                        return_document = ReturnDocument.AFTER))

输出：

{'_id': 5, 'name': 'Raju', 'Branch': 'CSE'}