[release 0.6.1] Querying a Custom Taxonomy on Product will list all terms, not just the ones associated to the product

[ardiewen]

Describe the bug
I have a custom taxonomy on Product called: Collections.

For collections, I have the terms Spring/Summer, and Fall/Winter.

I have a single product and have assigned the term Spring/Summer to it.

However, when I query the product like so:

{
    products {
        collections {
            nodes {
                name
            }
        }
    }
}

I receive both Spring/Summer and Fall/Winter instead of just Spring/Summer. I believe this is a regression from v0.5.1 since the expected behaviour was to return only the linked terms of the taxonomy.

[ardiewen]

Swapped over to the develop branch of the plugin with #346 applied and the opposite is actually happening now.

When querying a custom taxonomy, like above, the result is an empty array of nodes even when there are terms associated with the product. E.g.

Query:

{
  products {
    nodes {
      collections {
        nodes {
          name
        }
      }
    }
  }
}

Result:

{
  "data": {
    "products": {
      "nodes": [
        {
          "collections": {
            "nodes": []
          }
        },
        {
          "collections": {
            "nodes": []
          }
        },
        {
          "collections": {
            "nodes": []
          }
        },
        {
          "collections": {
            "nodes": []
          }
        },
        {
          "collections": {
            "nodes": []
          }
        },
        {
          "collections": {
            "nodes": []
          }
        }
      ]
    }
  }
}

[jacobarriola]

@ardiewen I think I see the issue with my PR. I mistakenly assumed all requests coming through would be $attributes, not taxonomies.

@kidunot89 Using get_the_terms() works better for this issue and my issue. Want me to get another PR rolling?

$resolver = new TermObjectConnectionResolver( $source, $args, $context, $info, $tax_object->name );

$terms = wp_list_pluck( get_the_terms( $source->ID, $tax_object->name ), 'term_id' );

$resolver->set_query_arg( 'term_taxonomy_id', ! empty( $terms ) ? $terms : array( '0' ) );

return $resolver->get_connection();

[jacobarriola]

@ardiewen I've got the PR up, so hopefully it solves both of our issues once it's merged in. It's testing good for me (both attributes and product categories).