关于python中使用mongodb模块，save和insert的小问题

作者：csc1520075 | 来源：互联网 | 2023-05-24 19:15

今天写python脚本的时候发现这样一个问题：importos,string,datetime,pymongo;connpymongo.Connection(&qu

　　今天写python脚本的时候发现这样一个问题：

import os , string , datetime ,pymongo;
conn = pymongo.Connection("127.0.0.1",27017);
db = conn.nn;
coll = db.nn_res;
value = dict(name="user1",num="1");
coll.save(value);
coll.insert(value);

View Code

　　执行脚本之后会发现，save和insert只执行了一条，而且跟insert和save出现的先后顺序没有关系，然后我去查看官网上关于save和insert的说明，发现save的部分解释是这样的：

db.collection.save(document)

Updates an existing document or inserts a new document, depending on its document parameter.

The save() method takes the following parameter:
    Parameter     Type     Description
    document     document     A document to save to the collection.

    If the document does not contain an _id field, then the save() method performs an insert. During the operation, mongod will add to the document the _id field and assign it a unique ObjectId.

    If the document contains an _id field, then the save() method performs an upsert, querying the collection on the _id field. If a document does not exist with the specified _id value, the save() method performs an insert. If a document exists with the specified _id value, the save() method performs an update that replaces all fields in the existing document with the fields from the document.

View Code

　　于是我猜想这个“_id"域是我们在创建对象的时候就被分配好了的，而不是在插入mongodb之后，数据库随机分配一个给我们的，于是我这样做:　

import os , string , datetime ,pymongo;
conn = pymongo.Connection("127.0.0.1",27017);
db = conn.nn;
coll = db.nn_res;
value1 = dict(name="user1",num="1");
value2 = dict(name="user1",num="1");
coll.save(value1);
coll.insert(value2);