Want to update inner field in a MongoDB

To update the inner field, use the below syntax −

db.yourCollectionName.update({"_id" : yourObjectId},
{$set : {"yourOuterFieldName.yourInnerFieldName" :yourValue}});

Let us first create a collection with documents −

> db.updateDocumentDemo.insertOne(
...   {
...
...      "StudentDetails" : {
...         "StudentFirstName" : "Adam",
...         "StudentLastName" : "Samith"
...      },
...      "StudentOtherDetails" : {
...         "StudentFavouriteSubject" : "MySQL",
...         "StudentScore" : 45
...      }
...   }
... );
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cd50bb32cba06f46efe9efe")
}

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

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

This will produce the following output −

{
   "_id" : ObjectId("5cd50bb32cba06f46efe9efe"),
   "StudentDetails" : {
      "StudentFirstName" : "Adam",
      "StudentLastName" : "Samith"
   },
   "StudentOtherDetails" : {
      "StudentFavouriteSubject" : "MySQL",
      "StudentScore" : 45
   }
}

Following is the query to update the document in MongoDB −

> db.updateDocumentDemo.update({"_id" : ObjectId("5cd50bb32cba06f46efe9efe")},
... {$set : {"StudentOtherDetails.StudentFavouriteSubject" :"MongoDB"}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Let us display the documents once again −

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

This will produce the following output −

{
   "_id" : ObjectId("5cd50bb32cba06f46efe9efe"),
   "StudentDetails" : {
      "StudentFirstName" : "Adam",
      "StudentLastName" : "Samith"
   },
   "StudentOtherDetails" : {
      "StudentFavouriteSubject" : "MongoDB",
      "StudentScore" : 45
   }
}