Support include directive

[manishrjain]

We should support @include directive.

{
  var shareids(eq(_share_hash_, "hash"))

  me(id: var(shareids)) { # gives you share ids.
    _share_  @include(if: gt(count(var(shareids)), 1))
  }
}

[MichelDiz]

This @include directive as an if statement is a very interesting feature we can use in Dgraph.
btw there's a "@skip" directive that does the opposite.

PS. Also could be useful with passwords type.

query search($userid: string, $password: string){
      user(func: uid($userid)) {
        pin as checkpwd(dgraph.password, $password) #only representing
        director.film @include(if: val(pin)) { #return if pin is true
          uid
           name @en
        }
      }
    }

With GraphQL Variables (something very similar as standard use of GraphQL)

curl localhost:8080/query -XPOST -H 'X-Dgraph-Vars: {"$a": "5", "$b": "10", "$name": "Steven Spielberg", "$director": true}' -d '
query test($a: int, $b: int, $name: string, $director: boolean) {
  me(func: allofterms(name@en, $name)) {
    name@en
    director.film @include(if: $director)  (first: $a, offset: $b) {
      name @en
      genre(first: $a) {
        name@en
      }
    }
  }
}' | python -m json.tool | less

The first example updated

{
 shareids as var(eq(_share_hash_, "hash"))

  me(func: uid(shareids)) { # gives you share ids.
       uid
    _share_  @include(if: gt(count(var(shareids)), 1)) {
       uid
       expand(_all_)
    }
  }
}

Original GraphQL usage

query Hero($episode: Episode, $withFriends: Boolean!) {
  hero(episode: $episode) {
    name
    friends @include(if: $withFriends) {
      name
    }
  }
}

source https://graphql.org/learn/queries/