How can I build a Form displaying a collection of collections?

Question

First of all, I have this DB schema:

I have categories, which contain products. I also have attributes (for example "color"), which contain values (for example "red", "green", etc).

So, finally, I can assign these attributes to products through the table ProductAttributeValues, that associates an attribute value to a product, this table is automatically created by Doctrine, because Product and AttributeValue have a ManyToMany relation between them.

This way I can have a category (cars) with products (Renault Megane, Ford Focus, etc). Each product can have multiple attributes with their values (color: gray, engine type: gasoline, etc). In this last example, the color is an Attribute, and gray is an AttributeValue. The engine type is another Attribute, and gasoline is an AttributeValue.

Ok, once I have my entities filled up with data (categories, attributes, attribute values, and products), how can I create a form to associate attributes and values for a given product?

More or less, the form should look like this:

So, as I'm in the "cars" category, I must display all attributes that belong to this category (engine and color). At the same time, I must display all values for these attributes (gasoline, diesel, electric... for the engine, and gray, red, blue... for the color).

Answer 1

You are not looking for collection field-types but entity field-types with a queryBuilder if you are trying to build a form like the one on your image.

With the entity field-type you can group your attributes by i.e. car.category.

... or you can use two entity fields and filter the results ( i.e. only showing attributes for category gas ) for the other selectbox in the field's queryBuilder. Best achieved by using an injected category property in your form builder being used in the queryBuilder's ->where() statement.

The collection form-type would be needed if you wanted to add/remove/edit multiple new categories or attributes to existing ones. but then your form would look different obviously.