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How to update a MongoDB document for adding a new item to an array?
To add a new item to an array, you can use $push operator. Let us first implement the following query to create a collection with documents:
> db.updateDemo.insertOne({"StudentName":"Larry","StudentCoreSubject":["Java","C"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c98ba78330fd0aa0d2fe4c9")
}
>db.updateDemo.insertOne({"StudentName":"Robert","StudentCoreSubject":["C++","MongoDB"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c98ba8b330fd0aa0d2fe4ca")
}
> db.updateDemo.insertOne({"StudentName":"Chris","StudentCoreSubject":["Python"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c98ba9b330fd0aa0d2fe4cb")
}Following is the query to display all the documents from a collection with the help of find() method
> db.updateDemo.find().pretty();
This will produce the following output
{
"_id" : ObjectId("5c98ba78330fd0aa0d2fe4c9"),
"StudentName" : "Larry",
"StudentCoreSubject" : [
"Java",
"C"
]
}
{
"_id" : ObjectId("5c98ba8b330fd0aa0d2fe4ca"),
"StudentName" : "Robert",
"StudentCoreSubject" : [
"C++",
"MongoDB"
]
}
{
"_id" : ObjectId("5c98ba9b330fd0aa0d2fe4cb"),
"StudentName" : "Chris",
"StudentCoreSubject" : [
"Python"
]
}Following is the query to add a new item to an array
> db.updateDemo.update( { _id:ObjectId("5c98ba78330fd0aa0d2fe4c9") }, { $push: { "StudentCoreSubject": "MySQL" } });
Updated 1 existing record(s) in 2ms
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Now check the item is inserted into the array or not
> db.updateDemo.find().pretty();
This will produce the following output. The string “MySQL” inserted successfully in the id 5c98ba78330fd0aa0d2fe4c9
{
"_id" : ObjectId("5c98ba78330fd0aa0d2fe4c9"),
"StudentName" : "Larry",
"StudentCoreSubject" : [
"Java",
"C",
"MySQL"
]
}
{
"_id" : ObjectId("5c98ba8b330fd0aa0d2fe4ca"),
"StudentName" : "Robert",
"StudentCoreSubject" : [
"C++",
"MongoDB"
]
}
{
"_id" : ObjectId("5c98ba9b330fd0aa0d2fe4cb"),
"StudentName" : "Chris",
"StudentCoreSubject" : [
"Python"
]
}
Updated on: 30-Jul-2019
198 Views
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