Bug Description

Observation in my app:
I have a contacts page where contacts can have tags and the same tag is shown shown multiple times.

I checked the dev api and saw that it only happens when using the "related type" (TagListConnection via contact tags field.)

Using a tags query directly works. (not via related type)
Using no filter yields duplicate nodes.
Using the related one while a filter is active does work.
Using the DISTINCT filter does not work. (also shows the duplicates)

Example:

This is the SQL for the following query:

query ContactsTags {
  contacts(last: 1) {
    totalCount
    edges {
      node {
        id
        name
        tags(filters: {DISTINCT: true}) {
          totalCount
          edges {
            node {
              id
              name
            }
          }
        }
      }
    }
  }
}

The result shoes 8 duplicate tags.

{
  "data": {
    "contacts": {
      "totalCount": 63,
      "edges": [
        {
          "node": {
            "id": "SOMEID==",
            "name": "Carmen",
            "tags": {
              "totalCount": 8,
              "edges": [
                {
                  "node": {
                    "id": "VGFnOjYy",
                    "name": "target"
                  }
                },
                {
                  "node": {
                    "id": "VGFnOjYy",
                    "name": "target"
                  }
                },
                ...  // 5 more here
                {
                  "node": {
                    "id": "VGFnOjYy",
                    "name": "target"
                  }
                }
              ]
            }
          }
        }
      ]
    }
  }
}

Using the django debug toolbar while running the query shows the following SQL information:

System Information

• Operating system: MacOSX
• Strawberry version (if applicable):

strawberry-graphql-django = "^0.49.1"
strawberry-graphql = "^0.247.0"

Additional Context

According to @bellini666 the general underlying issue of duplicates due to SQL is known.

Conversation snipet for context:

Basically, if you try to filter the relation through the original model, the join will generate spurious tuples. What you need to do in this case is to filter through a subquery with exists
BUT, having said that, I see that you used DISTINCT, which should also work
Can you check in the generated SQL if the distinct was not applied there? If not, then you just found a bug 😛