Fixed model class to be extended

[herodrigues]

Q	A
Doc fix?	yes
New docs?	no
Fixed tickets	#293

Custom models should extend core model class.

When trying to override Product model extending Sylius\Component\Product\Model\Product, it won't add all fields to the Product table in database.

• Extending Sylius\Component\Product\Model\Product as written in the docs:

Column	Type
id	integer
archetype_id	integer
available_on	timestamp(0) without time zone
created_at	timestamp(0) without time zone
updated_at	timestamp(0) without time zone
deleted_at	timestamp(0) without time zone

• Extending Sylius\Component\Core\Model\Product (same table as the default installation):

Column	Type
id	integer
archetype_id	integer
tax_category_id	integer
shipping_category_id	integer
restricted_zone	integer
available_on	timestamp(0) without time zone
created_at	timestamp(0) without time zone
updated_at	timestamp(0) without time zone
deleted_at	timestamp(0) without time zone
variant_selection_method	character varying(255)

Probably the same happens to the other models as related here #293

[pjedrzejewski]

Thanks for raising this @herodrigues. Actually, I think we are missing overriding guide for main Sylius. This is "Bundles General Guide" and it applies to users of individual bundles. So it is currently correct to extend component models and not the ones from the core. We should add this documentation to the main part - The Book or maybe Cookbook. And perhaps clarify it in the general guide that it is only for using bundles standalone. What do you think about that?

[herodrigues]

I'm developing a web system here where I work and I had to override some models. I'm not using individual bundles.
So, I'm not sure if this happens with other models.

Anyway, I think it's a good idea to clarify that in the documentation.
I had a lot work to do with Sylius here and I can start to write the documentation for main Sylius.

Should I close this PR and open one like "Overriding guide for main Sylius"?

[pjedrzejewski]

@herodrigues I think it makes sense, but let's keep it in "The Book" section. Also, before you write any bigger chunk of docs, let's discuss it in a GitHub issues, maybe community will have some ideas and we can do it more efficiently with fewer iterations. :)

[herodrigues]

Great! That's awesome!

Later, I'm gonna open a issue related to this.