How can I query a relation within Matrix via GraphQL

[tremby]

I have products, and I have recipes.

When I view a product, I want to show a recipe which mentions that product as one of its ingredients.

The ingredients are currently modelled as a Matrix field recipeIngredients, with one block type, ingredient. That block type has a few fields, one of which is a regular Craft entry relation field, linkedProduct.

How can I construct my GQL query to fetch recipe entries which refer to a given product in (at least) one of those matrix blocks? I have the relevant product's site ID, section, ID, and URI.

To complicate it, the recipe type has another relation field which points to products, relatedProducts, and I do not want to take any relations here into account (they are not necessarily ingredients). To be clear, if the product is related both here and in an ingredient, that's fine, it should be included. But not if it's only mentioned in relatedProducts, and not in recipeIngredients.

Do I want relatedTo? relatedToEntries? The documentation on both is confusing. The in-GQL documentation is unhelpful since it says one takes QueryArgument which just says it's a string or integer or boolean with no clue on what specifically they do (and searching for QueryArgument in the Craft docs does not turn up anything useful), and the other takes EntryCriteriaInput, which has a ton of fields, none of which is linkedProduct or recipeIngredients.

[brandonkelly]

There’s not a great way to do this right now.

You could preload all the recipe + ingredient relations up front as part of your build pipeline, and reference that locally, if that’s an option.

Otherwise, if you really need to find related recipes on the fly, you could add a “Combined Products” relation field to the Recipes section, and set its value dynamically when recipes are saved.

use craft\base\Event;
use craft\elements\Entry;
use craft\events\ModelEvent;
use craft\fields\BaseRelationField;

Event::on(Entry::class, Entry::EVENT_AFTER_PROPAGATE, function(ModelEvent $event) {
    /** @var Entry $entry */
    $entry = $event->sender;

    // is this entry in the Recipes section?
    if ($entry->section?->handle === 'recipes') {
        // get all the products related to its ingredients
        $productIds = [];
        foreach ($entry->ingredients->with('ingredient:product') as $ingredient) {
            foreach ($ingredient->product as $product) {
                $productIds[] = $product->id;
            }
        }

        /** @var BaseRelationField $field */
        $field = Craft::$app->fields->getFieldByHandle('combinedProducts', 'global');
        Craft::$app->relations->saveRelations($field, $entry, $productIds);
    }
});

In that code I’m assuming:

• the section handle is recipes
• the Matrix field handle is ingredient
• the nested product relation field handle is product
• the newly-created “Combined Products” relation field handle is combinedProducts

(Adjust accordingly.)

You can even hide that “Combined Products” field from view for authors, by setting an admin-only condition on the field within the Recipe entry type’s field layout.

With that in place, you could grab the related recipes using the relatedTo argument, or relatedToEntries (or whatever the appropriate variant is).

[tremby]

That's helpful; thanks.

You could preload all the recipe + ingredient relations up front as part of your build pipeline

There's something like 12,000 products so I don't think we can do this.

The other option looks reasonable; thank you for the example code.

With that in place, you could grab the related recipes using the relatedTo argument, or relatedToEntries (or whatever the appropriate variant is).

Can you help with this part, please? As far as I can tell from the docs, relatedTo lets me query for those matching one or more IDs, but doesn't allow me to tell it a specific relation field to look at. As I mentioned before, there's another field which also references products, which mustn't be allowed to poison the results.

Meanwhile, relatedToEntries looks to have a more sophisticated input form but I see no "field" or "via" or "through" or "relation" field here either.

In case it's not clear, I need to do something akin to

query {
  recipeEntries(
    relatedToEntries: {
      id: $myId
      viaField: "referencedIngredients"
    }
  ) {
    title
  }
}

But I see nothing in the GQL API to fill the role of viaField above.

[brandonkelly]

Sorry, I should have mentioned, you can target that specific field using the field’s own argument:

query {
  recipeEntries(
    referencedIngredients: $myId
  ) {
    title
  }
}

[tremby]

Oh wow, that's simpler than I expected.

I have it all working. Thanks so much for your help.

[brandonkelly]

Glad to hear!