$each modifier with $push in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the $push operator do in MongoDB?

The $push operator adds a value to an array field in a MongoDB document. If the field does not exist, it creates the array with the value.

beginner

What is the purpose of the $each modifier when used with $push?

$each allows you to add multiple values to an array at once instead of pushing one value at a time.

beginner

How would you add multiple items ["apple", "banana", "cherry"] to an array field fruits using $push and $each?

{ $push: { fruits: { $each: ["apple", "banana", "cherry"] } } }

intermediate

Can $each be combined with other modifiers like $sort or $slice?

Yes, $each can be combined with $sort to sort the array after pushing, and $slice to limit the array size.

beginner

What happens if you use $push without $each to add multiple values?

Without $each, $push treats the entire list as a single element and adds it as one item to the array.

What does $each do when used with $push in MongoDB?

A Adds multiple values to an array at once

B Removes multiple values from an array

C Sorts the array elements

D Creates a new collection

$each allows adding multiple values to an array in one operation with $push.

Which of the following is the correct syntax to add multiple items to an array field tags?

A { $addToSet: { tags: ["red", "blue"] } }

B { $push: { tags: ["red", "blue"] } }

C { $push: { tags: { $add: ["red", "blue"] } } }

D { $push: { tags: { $each: ["red", "blue"] } } }

Using $each inside $push is the correct way to add multiple values.

What happens if you push an array without $each?

A The entire array is added as one element

B Each element is added separately

C The operation fails

D The array is ignored

Without $each, the array is treated as a single element and pushed as is.

Can $each be used with $sort inside $push?

A Only with <code>$slice</code>, not <code>$sort</code>

B No, they cannot be combined

C Yes, to sort the array after pushing

D Only in aggregation pipelines

$each can be combined with $sort to sort the array after adding new elements.

Which operator creates an array field if it does not exist when pushing values?

A $addToSet

B $push

C $set

D $unset

$push creates the array field if it does not exist before adding values.

Explain how to add multiple items to an array field in MongoDB using $push and $each.

Think about pushing many items at once instead of one by one.

Describe what happens if you use $push without $each to add multiple values.

Consider how MongoDB treats the value given to $push.