Question

我在Mongodb工作的文件：

{ "_id" : 3, "sid" : 2, "name" : "A", "score" : 60 }
{ "_id" : 5, "sid" : 3, "name" : "B", "score" : 50 }
{ "_id" : 2, "sid" : 1, "name" : "C", "score" : 44 }
{ "_id" : 1, "sid" : 0, "name" : "D", "score" : 14 }
{ "_id" : 4, "sid" : 4, "name" : "E", "score" : 28 }
{ "_id" : 8, "sid" : 3, "name" : "B", "score" : 92 }
{ "_id" : 6, "sid" : 0, "name" : "D", "score" : 63 }
{ "_id" : 9, "sid" : 4, "name" : "E", "score" : 5 }
{ "_id" : 10, "sid" : 6, "name" : "F", "score" : 81 }
{ "_id" : 11, "sid" : 5, "name" : "G", "score" : 23 }
{ "_id" : 13, "sid" : 8, "name" : "H", "score" : 67 }
{ "_id" : 14, "sid" : 6, "name" : "F", "score" : 89 }
{ "_id" : 12, "sid" : 9, "name" : "I", "score" : 75 }
{ "_id" : 15, "sid" : 7, "name" : "J", "score" : 85 }
{ "_id" : 7, "sid" : 1, "name" : "C", "score" : 21 }
{ "_id" : 16, "sid" : 9, "name" : "I", "score" : 16 }
{ "_id" : 17, "sid" : 8, "name" : "H", "score" : 66 }
{ "_id" : 19, "sid" : 7, "name" : "J", "score" : 63 }
{ "_id" : 18, "sid" : 2, "name" : "A", "score" : 97 }
{ "_id" : 20, "sid" : 5, "name" : "G", "score" : 41 }

我有一个变量＆＃34; low＆＃34;，包含每个学生的较低分数：

{ "name" : "F", "score" : 81 }
{ "name" : "H", "score" : 66 }
{ "name" : "J", "score" : 63 }
{ "name" : "A", "score" : 60 }
{ "name" : "B", "score" : 50 }
{ "name" : "G", "score" : 23 }
{ "name" : "C", "score" : 21 }
{ "name" : "I", "score" : 16 }
{ "name" : "D", "score" : 14 }
{ "name" : "E", "score" : 5 }

我正在尝试检索名称＆＃34; A＆＃34;的得分值。并将其更新为65.

我该怎么做？

Answer 1

假设您在本地上下文中有变量low，那么您可以像这样使用普通的JavaScript：

> db.coll.find()                                                                                                                       
{ "_id" : ObjectId("57204c236b86b7f53c0e33fb"), "name" : "Ali", "score" : 81 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e33fc"), "name" : "Hamid", "score" : 66 }                                                       
{ "_id" : ObjectId("57204c236b86b7f53c0e33fd"), "name" : "Mo", "score" : 63 }                                                          
{ "_id" : ObjectId("57204c236b86b7f53c0e33fe"), "name" : "Pat", "score" : 60 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e33ff"), "name" : "Joe", "score" : 50 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e3400"), "name" : "Kurt", "score" : 23 }                                                        
> var low=db.coll.find({}, {_id:0});                                                                                                   
> var newarr=new Array();                                                                                                              
> low.forEach(function(item){                                                                                                          
... if(item.name=="Pat")                                                                                                               
...     item.score=65;                                                                                                                 
... newarr.push(item);                                                                                                                 
... });                                                                                                                                
> newarr                                                                                                                               
[                                                                                                                                      
        {                                                                                                                              
                "name" : "Ali",                                                                                                        
                "score" : 81                                                                                                           
        },                                                                                                                             
        {                                                                                                                              
                "name" : "Hamid",                                                                                                      
                "score" : 66                                                                                                           
        },                                                                                                                             
        {                                                                                                                              
                "name" : "Mo",                                                                                                         
                "score" : 63                                                                                                           
        },                                                                                                                             
        {                                                                                                                              
                "name" : "Pat",                                                                                                        
                "score" : 65                                                                                                           
        },                                                                                                                             
        {                                                                                                                              
                "name" : "Joe",                                                                                                        
                "score" : 50                                                                                                           
        },                                                                                                                             
        {                                                                                                                              
                "name" : "Kurt",                                                                                                       
                "score" : 23                                                                                                           
        }                                                                                                                              
] 
>

如果您想要更新到集合中，可以使用：

> db.coll.find()                                                                                                                       
{ "_id" : ObjectId("57204c236b86b7f53c0e33fb"), "name" : "Ali", "score" : 81 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e33fc"), "name" : "Hamid", "score" : 66 }                                                       
{ "_id" : ObjectId("57204c236b86b7f53c0e33fd"), "name" : "Mo", "score" : 63 }                                                          
{ "_id" : ObjectId("57204c236b86b7f53c0e33fe"), "name" : "Pat", "score" : 60 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e33ff"), "name" : "Joe", "score" : 50 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e3400"), "name" : "Kurt", "score" : 23 }                                                        
> db.coll.update({name:"Pat"}, {$set: {score:65}})                                                                                     
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })                                                                      
> db.coll.find()                                                                                                                       
{ "_id" : ObjectId("57204c236b86b7f53c0e33fb"), "name" : "Ali", "score" : 81 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e33fc"), "name" : "Hamid", "score" : 66 }                                                       
{ "_id" : ObjectId("57204c236b86b7f53c0e33fd"), "name" : "Mo", "score" : 63 }                                                          
{ "_id" : ObjectId("57204c236b86b7f53c0e33fe"), "name" : "Pat", "score" : 65 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e33ff"), "name" : "Joe", "score" : 50 }                                                         
{ "_id" : ObjectId("57204c236b86b7f53c0e3400"), "name" : "Kurt", "score" : 23 }                                                        
>

打印存储在变量中的密钥的值，以mongodb为单位

1 个答案: