$include

The $include projection operator is used in queries to specify the fields that should be returned in the result documents. By using $include, you can choose to retrieve only fields of interest, making your query more efficient by minimizing the amount of data returned.

The syntax for $include is as follows:

{
  field: 1;
}

Here, field is the name of the field to include, and 1 indicates that you want the field included in the result documents. You can include multiple fields by specifying them in a comma-separated list:

{ field1: 1, field2: 1, field3: 1 }

Example

Suppose we have a collection called books with the following documents:

[
  {
    title: 'The Catcher in the Rye',
    author: 'J.D. Salinger',
    year: 1951,
    genre: 'Literary fiction',
  },
  {
    title: 'To Kill a Mockingbird',
    author: 'Harper Lee',
    year: 1960,
    genre: 'Southern Gothic',
  },
  {
    title: 'Of Mice and Men',
    author: 'John Steinbeck',
    year: 1937,
    genre: 'Novella',
  },
];

If you want to retrieve only the title and author fields from the documents in the books collection, you can use the $include projection operator as follows:

db.books.find({}, { title: 1, author: 1, _id: 0 });

The result will be:

[
  {
    title: 'The Catcher in the Rye',
    author: 'J.D. Salinger',
  },
  {
    title: 'To Kill a Mockingbird',
    author: 'Harper Lee',
  },
  {
    title: 'Of Mice and Men',
    author: 'John Steinbeck',
  },
];

Note that we have also excluded the _id field (which is included by default) by setting it to 0.

Keep in mind that you cannot combine $include and $exclude (or 1 and 0) in the same query, except for the _id field, which can be excluded even when other fields are being included.

$include

Example

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