Excluding fields from results in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

How do you exclude a field from the results in a MongoDB query?

Use the projection parameter in the find() method with the field set to 0. For example, { fieldName: 0 } excludes that field from the results.

beginner

What does setting a field to 0 in MongoDB projection do?

It tells MongoDB to exclude that field from the documents returned by the query.

beginner

Can you exclude the _id field in MongoDB query results? How?

Yes, by setting _id: 0 in the projection part of the find() method, you exclude the _id field from the results.

intermediate

What happens if you mix including and excluding fields in MongoDB projection?

MongoDB does not allow mixing inclusion (1) and exclusion (0) in the same projection except for the _id field. You must choose either to include or exclude fields.

beginner

Example: How to exclude the 'password' field from user documents in MongoDB?

Use find({}, { password: 0 }) to get all user documents but without the 'password' field in the results.

In MongoDB, how do you exclude the 'email' field from query results?

A Use { email: 0 } in the projection

B Use { email: 1 } in the projection

C Use { email: false } in the query filter

D Use { email: null } in the projection

Setting a field to 0 in the projection excludes it from the results.

What is the default behavior of the _id field in MongoDB query results?

A _id is excluded by default

B _id is included by default

C _id is included only if specified

D _id is excluded if any field is included

MongoDB includes the _id field by default unless you explicitly exclude it with _id: 0.

Which of the following is NOT allowed in MongoDB projection?

A Mixing inclusion and exclusion of fields except _id

B Excluding the _id field

C Including specific fields only

D Excluding specific fields only

MongoDB does not allow mixing inclusion and exclusion in the same projection except for the _id field.

How to exclude multiple fields, 'password' and 'ssn', from MongoDB query results?

A { password: false, ssn: false }

B { password: 1, ssn: 1 }

C { password: 0, ssn: 0 }

D { password: null, ssn: null }

Set each field to 0 in the projection to exclude them.

If you want to include only the 'name' and 'age' fields in MongoDB results, what should the projection be?

A { name: 0, age: 1 }

B { name: 0, age: 0 }

C { name: true, age: false }

D { name: 1, age: 1 }

Setting fields to 1 includes only those fields in the results.

Explain how to exclude fields from MongoDB query results and any important rules to remember.

Think about the projection parameter in find() and the special case of _id.

Describe a real-life scenario where excluding fields from MongoDB results is useful.

Consider privacy and efficiency when sharing data.