How to Add Field in MongoDB

To add a field in MongoDB, you can use the $set operator to update the document. For example, if you want to add a field named newField in a document within a collection, you can use the following command:

db.collection.update(
   { <query> },
   { $set: { newField: <value> } }
)

In this case, serves as the condition for selecting the documents to update, while represents the value to be set for the new field. If you want to add the newField field to all documents, you can set the query condition as an empty object {}.

Moreover, you can also use the $push operator to add new elements to an array field, and the $addToSet operator to add new elements to a set field.