Spring Data MongoDB query with multiple optional parameters $in Collection - mongodb

Question

I have a use case where my query need to find based on 3 optional fields and one of them is pass in as a collection.
The "3 optional fields" part is already solved by this post
Spring Data MongoDB AND/OR query with multiple optional parameters
However, I am runnig into the issue with the $in for the collection filed.
For example, in the following query
{ $and :
[{
$and:
[
{$or : [ { $where: '?0 == null' } , { a : ?0 }]},
{$or : [ { $where: '?1 == null' } , { b : ?1 }]},
{$or : [ { $where: '?2 == null' } , { c : ?2 }]}
]
}]
}
In my case, the field a is actually pass in as a collection, I need to find those object in MongoDB with filed a is $in the collection I passed in.
I have tried with something like this
{ $and :
[{
$and:
[
{$or : [ { $where: '?0 == null' } , { a : { $in : ?0 }}]},
{$or : [ { $where: '?1 == null' } , { b : ?1 }]},
{$or : [ { $where: '?2 == null' } , { c : ?2 }]}
]
}]
}
However, I got NPE for this when I pass in a null collection.

Answer 1

You need to test the collection length, as shown here spring-data-mongo - optional query parameters?
You can also get rid of the top-level $and.
{ $and :
[
{$or : [ { $where: '?0.length == 0' } , { a : { $in : ?0 }}]},
{$or : [ { $where: '?1 == null' } , { b : ?1 }]},
{$or : [ { $where: '?2 == null' } , { c : ?2 }]}
]
}

Answer 2

You actually can't use $in for optional list parameter because when not specified it will be null and $in accept only list. To do that You will have add [] around optional list parameter and then flatten this list like that:
{ $and :
[
{$or : [ { $where: '?0 == null;' },
{ $where: '[].concat.apply([],[?0]).indexOf(this.a) !== -1;'}]},
{$or : [ { $where: '?1 == null' } , { b : ?1 }]},
{$or : [ { $where: '?2 == null' } , { c : ?2 }]}
]
}
use that for mongo version < 3.4 and since 3.4 You can use includes function instead of indexOf