How to set a primary key in MongoDB?

Question

I want to set one of my fields as primary key. I am using MongoDB as my NoSQL.

Answer 1

One way of achieving this behaviour is by setting the value to _id (which is reserved for a primary key in MongoDB) field based on the custom fields you want to treat as primary key.
i.e. If I want employee_id as the primary key then at the time of creating document in MongoDB; assign _id value same as that of employee_id.