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?
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1 Answer
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.
