How do I push elements to an existing array in MongoDB?

To push elements to an existing array, use $addToSet operator along with update(). Let us first create a collection with documents −

> db.pushElements.insertOne({"Comments":["Good","Awesome","Nice"]});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cd682597924bb85b3f48953")
}

Following is the query to display all documents from a collection with the help of find() method −

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

This will produce the following output −

{
   "_id" : ObjectId("5cd682597924bb85b3f48953"),
   "Comments" : [
      "Good",
      "Awesome",
      "Nice"
   ]
}

Following is the query to push elements to an existing array in MongoDB −

> db.pushElements.update(
   {_id:ObjectId("5cd682597924bb85b3f48953")},
   { "$addToSet":{"Comments":"Cool"} },
   upsert=true
);
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Let us check the document once again −

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

This will produce the following output −

{
   "_id" : ObjectId("5cd682597924bb85b3f48953"),
   "Comments" : [
      "Good",
      "Awesome",
      "Nice",
      "Cool"
   ]
}

Anvi Jain

Published on 13-Jun-2019 07:32:48

• Related Questions & Answers
• How to push an array in MongoDB?
• How to push an element into array in MongoDB?
• Updating an array with $push in MongoDB
• How do I $set and $push in single update with MongoDB?
• How do I add a field to existing record in MongoDB?
• MongoDB query to push document into an array
• Cannot push into an array from MongoDB?
• MongoDB $push in nested array?
• How to push new items to an array inside of an object in MongoDB?
• How do I recursively remove consecutive duplicate elements from an array?
• How to add items/elements to an existing jagged array in C#?
• How do I remove elements not matching conditions in MongoDB?
• How do I make an array with unique elements (remove duplicates) - JavaScript?
• How do I add a value to the top of an array in MongoDB?
• How do I remove a string from an array in a MongoDB document?