在Mongodb和GOlang中删除另一个对象内的对象

问题描述

我想删除一个对象中的特定对象，我的对象：

{
    "_id" : ObjectId("5f577f3cce031ee00f5e32c9"),"UserId" : 0,"firstname" : "user 1","lastname" : "user 1","finishedTrainings" : [
        {
            "itemId" : 3,"validationscore" : 1,"timestamps" : {
                "createdat" : ISODate("2020-09-09T12:57:31.275Z"),"createdby" : 0,"updatedat" : ISODate("0001-01-01T00:00:00Z"),"updatedby" : 0
            },"isValidated" : true
        },{
            "itemId" : 0,"validationscore" : 0.6666666666666666,"timestamps" : {
                "createdat" : ISODate("2020-09-09T12:59:04.268Z"),"isValidated" : true
        }
    ],"biography" : ""
}

我想删除finishedTraining（id = 3），mongodb中的语法是什么

解决方法

//从mongo shell 4.2，windows10输出的代码

//data set as given in problem statement
> db.userTraining.find().pretty();
{
        "_id" : ObjectId("5f577f3cce031ee00f5e32c9"),"UserId" : 0,"firstname" : "user 1","lastname" : "user 1","finishedTrainings" : [
                {
                        "itemId" : 3,"validationScore" : 1,"timestamps" : {
                                "createdat" : ISODate("2020-09-09T12:57:31.275Z"),"createdby" : 0,"updatedat" : ISODate("0001-01-01T00:00:00Z"),"updatedby" : 0
                        },"isValidated" : true
                },{
                        "itemId" : 0,"validationScore" : 0.6666666666666666,"timestamps" : {
                                "createdat" : ISODate("2020-09-09T12:59:04.268Z"),"isValidated" : true
                }
        ],"biography" : ""
}
//assuming objectID is unique for the document,you can query your own business field
> db.userTraining.update(
... {_id:ObjectId("5f577f3cce031ee00f5e32c9")},... {$pull:{"finishedTrainings":{itemId:3}}},... false,... true
... );
WriteResult({ "nMatched" : 1,"nUpserted" : 0,"nModified" : 1 })
> db.userTraining.find().pretty();
{
        "_id" : ObjectId("5f577f3cce031ee00f5e32c9"),"finishedTrainings" : [
                {
                        "itemId" : 0,"biography" : ""
}
>
//above id=3 is deleted object from the array,other document object remain intact by using "$pull" in the update statement