External IDs and Upsert Block - Mutations

Documentation
1

The upsert block makes managing external IDs easy.

Set the schema.

xid: string @index(exact) .
<http://schema.org/name>: string @index(exact) .
<http://schema.org/type>: [uid] @reverse .

Set the type first of all.

{
  set {
    _:blank <xid> "http://schema.org/Person" .
    _:blank <dgraph.type> "ExternalType" .
  }
}

Now you can create a new person and attach its type using the upsert block.

   upsert {
      query {
        var(func: eq(xid, "http://schema.org/Person")) {
          Type as uid
        }
        var(func: eq(<http://schema.org/name>, "Robin Wright")) {
          Person as uid
        }
      }
      mutation {
          set {
           uid(Person) <xid> "https://www.themoviedb.org/person/32-robin-wright" .
           uid(Person) <http://schema.org/type> uid(Type) .
           uid(Person) <http://schema.org/name> "Robin Wright" .
           uid(Person) <dgraph.type> "Person" .
          }
      }
    }

You can also delete a person and detach the relation between Type and Person Node. It’s the same as above, but you use the keyword “delete” instead of “set”. “http://schema.org/Person” will remain but “Robin Wright” will be deleted.

   upsert {
      query {
        var(func: eq(xid, "http://schema.org/Person")) {
          Type as uid
        }
        var(func: eq(<http://schema.org/name>, "Robin Wright")) {
          Person as uid
        }
      }
      mutation {
          delete {
           uid(Person) <xid> "https://www.themoviedb.org/person/32-robin-wright" .
           uid(Person) <http://schema.org/type> uid(Type) .
           uid(Person) <http://schema.org/name> "Robin Wright" .
           uid(Person) <dgraph.type> "Person" .
          }
      }
    }

Query by user.

{
  q(func: eq(<http://schema.org/name>, "Robin Wright")) {
    uid
    xid
    <http://schema.org/name>
    <http://schema.org/type> {
      uid
      xid
    }
  }
}
This is a companion discussion topic for the original entry at https://dgraph.io/docs/mutations/extrenal-ids-upsert-block/