MongoDB中如何推入数组？
要使用MongoDB推送到数组中，请使用$push。让我们创建一个包含文档的集合-
> db.demo445.insertOne({"ListOfFriends":["Robert","Mike","Sam","Carol","David","Mike"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e78f099bbc41e36cc3caec2")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo445.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5e78f099bbc41e36cc3caec2"),
"ListOfFriends" : [
"Robert",
"Mike",
"Sam",
"Carol",
"David",
"Mike"
]
}以下是推入数组的查询-
> db.demo445.update(
... { _id: ObjectId("5e78f099bbc41e36cc3caec2") },
... { $push: { ListOfFriends: "Chris Brown" } }
... )
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })在find()方法的帮助下显示集合中的所有文档-
> db.demo445.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5e78f099bbc41e36cc3caec2"),
"ListOfFriends" : [
"Robert",
"Mike",
"Sam",
"Carol",
"David",
"Mike",
"Chris Brown"
]
}