Syntax error How to add new item in nested array with MongoDB?

How to add new item in nested array with MongoDB?



For this, use find() along with update(). Let us create a collection with documents −

> db.demo124.insertOne(
...    {
...       "Name" : "John",
...       "Id" : 101,
...       "ProjectDetails" : [{
...          "ProjectName1" : "Online Book",
...          "ProjectName2" : "Online Banking"
...    }, {
...          "ProjectName1" : "Online Library Management System",
...          "ProjectName2" : "School Management System"
...       }]
...    }
... );
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e2f2c8b140daf4c2a3544bb")
}

Display all documents from a collection with the help of find() method −

> db.demo124.find();

This will produce the following output −

{
   "_id" : ObjectId("5e2f2c8b140daf4c2a3544bb"), "Name" : "John", "Id" : 101, "ProjectDetails" : [
      { "ProjectName1" : "Online Book", "ProjectName2" : "Online Banking" },
      { "ProjectName1" : "Online Library Management System", "ProjectName2" : "School Management System" }
   ] 
}

Following is the query to add new item in nested array −

> db.demo124.find().toArray().forEach(
...    function(d){
...       for(var i = 0; i< d.ProjectDetails.length; ++i) {
...          d.ProjectDetails[i]['ProjectName3'] = 'Online Snake Game';
...       }
...       db.demo124.update({_id: d._id}, d);
...    }
... );

Display all documents from a collection with the help of find() method −

> db.demo124.find().pretty();

This will produce the following output −

{
   "_id" : ObjectId("5e2f2c8b140daf4c2a3544bb"),
   "Name" : "John",
   "Id" : 101,
   "ProjectDetails" : [
      {
         "ProjectName1" : "Online Book",
         "ProjectName2" : "Online Banking",
         "ProjectName3" : "Online Snake Game"
      },
      {
         "ProjectName1" : "Online Library Management System",
         "ProjectName2" : "School Management System",
         "ProjectName3" : "Online Snake Game"
      }
   ]
}
Updated on: 2020-03-31T11:38:23+05:30

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