如何在嵌套数组中查找和修改值？
要查找和修改嵌套数组中的值，可以使用update命令。首先让我们创建一个包含文档的集合
> db.findAndModifyAValueInNestedArrayDemo.insertOne( { "CompanyName" :
"Amazon", "DeveloperDetails" : [ { "ProjectName" : "Online Book
Store", "TeamSize" : "5" }, { "ProjectName" : "Library
Management System", "TeamSize" : "7" }, { "ProjectName" :
"Online Banking Application", "TeamSize" : "15" } ] } );
{
"acknowledged" : true,
"insertedId" : ObjectId("5ca275226304881c5ce84b9f")
}以下是在find()方法的帮助下显示集合中所有文档的查询
> db.findAndModifyAValueInNestedArrayDemo.find().pretty();
这将产生以下输出
{
"_id" : ObjectId("5ca275226304881c5ce84b9f"),
"CompanyName" : "Amazon",
"DeveloperDetails" : [
{
"ProjectName" : "Online Book Store",
"TeamSize" : "5"
},
{
"ProjectName" : "Library Management System",
"TeamSize" : "7"
},
{
"ProjectName" : "Online Banking Application",
"TeamSize" : "15"
}
]
}以下是在嵌套数组中查找和修改值的查询。我们正在将ProjectName的TeamSize修改为20：“在线银行应用程序”
> db.findAndModifyAValueInNestedArrayDemo.update( { DeveloperDetails: { $elemMatch: {
ProjectName: "Online Banking Application" } } }, { $set: { 'DeveloperDetails.$.TeamSize':
'20' } } );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })让我们检查文档是否被修改为20
> db.findAndModifyAValueInNestedArrayDemo.find().pretty();
这将产生以下输出
{
"_id" : ObjectId("5ca275226304881c5ce84b9f"),
"CompanyName" : "Amazon",
"DeveloperDetails" : [
{
"ProjectName" : "Online Book Store",
"TeamSize" : "5"
},
{
"ProjectName" : "Library Management System",
"TeamSize" : "7"
},
{
"ProjectName" : "Online Banking Application",
"TeamSize" : "20"
}
]
}