Using @cascade with expand

Users Dgraph
1

While testing dgraph on Dgraph Ratel Dashboard I started testing the usage of @cascade with expand

So I try this and it works as expected:

{
  actors(func: type(Actor), first: 10) {
  	uid
  	name@.
  	dgraph.type
  	expand(_all_) @filter(type(Performance)) {
        dgraph.type
        performance.film {
        uid
        name@.
      }
	}  
  }
}

But if try to use @cascade it returns empty data, is that right?

{
  actors(func: type(Actor), first: 10) @cascade {
  	uid
  	name@.
  	dgraph.type
  	expand(_all_) @filter(type(Performance)) {
        dgraph.type
        performance.film {
        uid
        name@.
      }
	}  
  }
}

The query I’m trying to achieve is to return all the nodes of type Actor that has an edge with the type Performance.

2

You shouldn’t use cascade with expand All. Certainly, Dgraph will verify if all nodes have absolutely all predicates and edges(in a traverse context). And it will return empty just because none of the nodes found to match this logic.

Remove expand all from the equation and use a predictable query structure.

3

@MichelDiz I don’t know if I got right but I tried this and it didn’t work:

{
  actors(func: type(Actor), first: 10) @cascade {
    uid
    name@.
    dgraph.type
    expand(Actor) {
      dgraph.type
      expand(Performance)
    }  
  }
}

https://play.dgraph.io/?latest

4

The short answer to what I said is that cascade won’t work easily with expand functions (Actually I think that it doesn’t even work at all). So, don’t use it.

This bellow works.

{
  actors(func: type(Actor), first: 10) @cascade {
    uid
    dgraph.type
    actor.film {
      dgraph.type
      performance.film {
        uid
        name@.
      }
    }  
  }
}