Filtering with $null does not work on relational or media fields.

[kocerb]

Bug Report

Describe the bug

When try to filter by a relational field or media type field is null or not Strapi throws error: Only $and, $or and $not can by used as root level operators. Found $null.

Steps to reproduce the behavior

1-) Create a collection type (let's say foo) that contains a relation with another collection type (let's say bar)
(or alternatively Create a collection type (let say foo) that contains a media type field (let's say bar))
2-) Send a GET request to the /foos?populate=*&filters[bar][$null]=true
3-) API returns 500 Internal Server Error and Strapi console logs the following message:

Only $and, $or and $not can by used as root level operators. Found $null.

Expected behavior

On the earlier versions of Strapi (v3) there was support to filter by a relational field is null or not with a similiar query.

System

Node.js version: v14.18.2
NPM version: v6.14.15
Strapi version: tried from v4.0.0 to v4.0.4
Database: Postgresql 10
Operating system: macOS v11.6

[derrickmehaffy]

We should be able to filter on the related key of a relation (same happens if you try to filter for things like IDs without specifying the nested ID like:

This Works

filters: {
  someRelation: {
    id: {
      $in: [ 1,2,3 ]
    }
  }
}

This Doesn't Work

filters: {
  someRelation: {
    $in: [ 1,2,3 ]
  }
}

And it should

[vallerydelexy]

@derrickmehaffy any workaround?

[derrickmehaffy]

@derrickmehaffy any workaround?

Use the relation.id as I mentioned what works in my previous comment.

[shailesh87]

Same issue;
Any update on this...

[hennzen]

What I did instead of not-working

  filters: {
    $and: [
      {
        somerelation: {
          $notNull: true
        }
      }
    ]
  }

is

  filters: {
    $and: [
      {
        somerelation: {
          id: {
            $gte: 1
          }
        }
      }
    ]
  }

[jai2826]

This solution worked for me!!

I have a content type name "foo" and have another relational field name "bar"
foo has many to many relation with bar
bar has only one field "name"
lets say bar= [jack, joe ,jill]
my fetch string is
......../api/foos?filters[bars][name]=jill&populate=*
(ignore "&populate=*" if you don't know)
This will list and populate all the foos which have bar named as jill

I hope it helps

[kraftdorian]

was able to get it working for the relation field type, using the notNull operator on the related content type fields:

findContentType({
  filters: {
    relationFieldName: {
      id: {  // also works on the UID field type
        $notNull: true,
      },
    },
  },
})

using Strapi v4.3.4

[VaibhavPaliwal0007]

How can I combine notNull and my condition?

Basically if the array is not empty then check for id

[strapi-bot]

This issue has been mentioned on Strapi Community Forum. There might be relevant details there:

https://forum.strapi.io/t/query-where-relationship-does-not-exist/20758/3