Question

I’m just curious what’s difference between .in() and .all() methods in mongoose Query?
Can you explain by a simple example.

Answer 1

Here is the explanation from mongodb.org:

$all

The $all operator is similar to $in, but instead of matching any value in the specified array all values in the array must be matched. For example, the object

{ a: [ 1, 2, 3 ] }

would be matched by

db.things.find( { a: { $all: [ 2, 3 ] } } );

but not

db.things.find( { a: { $all: [ 2, 3, 4 ] } } );

An array can have more elements than those specified by the $all criteria. $all specifies a minimum set of elements that must be matched.

Read more about mongodb operators here