Add new field to every document in a MongoDB collection

Question

How can I add a new field to every document in an existent collection?

I know how to update an existing document's field but not how to add a new field to every document in a collection. How can I do this in the mongo shell?

Answer 1

To add a new field to every document in a MongoDB collection you have to use empty selector, and set the multi flag to true to update all the documents as follows:-

db.your_collection.update( 

  {}, 

  { $set: {"new_field": 1} }, 

  false, 

  true 

)