如何在MongoDB中推送数组？
要推送数组，请在MongoDB中使用$push。首先让我们创建一个包含文档的集合-
> db.demo399.insertOne({Name:"Chris",Age:21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e610339fac4d418a017856d")
}
> db.demo399.insertOne({Name:"David",Age:22});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e610341fac4d418a017856e")
}
> db.demo399.insertOne({Name:"Chris",Age:21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e610355fac4d418a017856f")
}
> db.demo399.insertOne({Name:"Bob",Age:23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e61035efac4d418a0178570")
}
> db.demo399.insertOne({Name:"David",Age:22});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e610364fac4d418a0178571")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo399.find();
这将产生以下输出-
{ "_id" : ObjectId("5e610339fac4d418a017856d"), "Name" : "Chris", "Age" : 21 }
{ "_id" : ObjectId("5e610341fac4d418a017856e"), "Name" : "David", "Age" : 22 }
{ "_id" : ObjectId("5e610355fac4d418a017856f"), "Name" : "Chris", "Age" : 21 }
{ "_id" : ObjectId("5e61035efac4d418a0178570"), "Name" : "Bob", "Age" : 23 }
{ "_id" : ObjectId("5e610364fac4d418a0178571"), "Name" : "David", "Age" : 22 }以下是推送数组的查询-
> db.demo399.aggregate(
... [
... {
... $group:
... {
... _id: null,
... array: { $push: { Name: "$Name", Age: "$Age" } }
... }
... }
... ]
... )这将产生以下输出-
{ "_id" : null, "array" : [ { "Name" : "Chris", "Age" : 21 }, { "Name" : "David", "Age" : 22 }, { "Name" : "Chris", "Age" : 21 }, { "Name" : "Bob", "Age" : 23 }, { "Name" : "David", "Age" : 22 } ] }