Query for nodes that do not have predicate with connection to specific user node

Users Dgraph
, ,
1
  • I have a node (type “Post”).
  • That node is connected to many images.
  • Each image can have comments.
  • Each comment can be connected to one user.

I need to query for all images. Each image returned should not have a comment that is from the user with uid 0x1.

Additionally, I am trying to achieve the results without using vars?

Here is the query that I have come up with so far.

Query 
{
    query(func: uid("0x5")) {
        uid
        IsOwnedBy {
          uid
          username
        }
        hasImages @filter(has(hasComments)) {
          uid
          filename
          hasComments {
            uid
            text
            commentBy @filter(not uid("0x1")) {
              uid
              username
            }
            dgraph.type
          }
          created
          dgraph.type
        }
        created
        dgraph.type
    }
}

If I add not to @filter(not has(hasComments)), then it shows me all the images that does not have any comments. But I want images with or without comments, just not images that have comments from user 0x1.

If I have not on the commentBy @filter(not uid("0x1")) { filter, then I do not see the commentBy edge, but I still see the images that have comments from that user.

ImagesHaveComments

Dgraph metadata

v23.1.0

2

The only way I see to do this without using variables is to filter the results client side.

3

That sound like a perfect case for vars. To capture some information or UIDs and use it elsewhere in the query.

4

I am starting to agree. I have tried many permutations and even had ChatGPT suggest some options and while some have come close, nothing has been as effective as using variables. Not a big deal. I was just wondering if it was possible.

5

Why? What reasoning do you have for not using var blocks? Using var blocks will absolutely increase performance of your queries.

6

No good reason. Just learning still and seeing what is possible. That is good to know that using vars will help with performance.