MongoDB Projection

In MongoDB, projection means selecting only the data needed, rather than selecting all of the document 's data. If there are 5 fields in a document and you need to show only 3, then select only 3 fields from them.

The find() Method

The find() method of MongoDB, defined in the MongoDB Query Document, accepts the second optional parameter, which is a list of fields you want to retrieve. When you execute the find() method in MongoDB, all fields of a document are displayed. To limit this, a list of fields with a value of 1 or 0. must be set. 1 is used for showing a field, while 0 is used for hiding a field.

Syntax

The basic syntax with projection for the find() method is as follows.

>db.COLLECTION_NAME.find({},{KEY:1})

Example

Consider the collection mycol has the following data −

{_id : ObjectId("507f191e810c19729de860e1"), title: "MongoDB Overview"},
{_id : ObjectId("507f191e810c19729de860e2"), title: "NoSQL Overview"},
{_id : ObjectId("507f191e810c19729de860e3"), title: "phptpoint Over

The following example shows the title of the document when the document is being queried.

>db.mycol.find({},{"title":1,_id:0})
{"title":"MongoDB Overview"}
{"title":"NoSQL Overview"}
{"title":"phptpoint Overview"}
>

Please note _id field is always displayed while executing find() method, if you don't want this field, then you need to set it as 0.