Im learning mongodb and Im starting the searching commands but looking for an example i found this db.amigos.find({Nombre: "Marisa" },{Nombre:1, Apellidos:2})

What does :1 and :2 means?


That ",{Nombre:1, Apellidos:2}" part is 'projection', where you tell what fields you want to be in the result. Without it, all fields are included to result.

Normally you use

  • 0 to remove field
  • 1 to include a field

But, any positive value will work as "include field". This example find will return fields _id, Nombre, Apellidos

Field _id is always returned in the result IF it is not especially removed like:

db.amigos.find({Nombre: "Marisa" },{_id:0, Nombre:1, Apellidos:2})

If your projection have only "remove field" clauses, then all other fields are returned, but not those what you list, there

db.amigos.find({Nombre: "Marisa" },{_id:0, Apellidos:0})

So, now every field except _id and Apellidos is returned in the result.

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