Generate id for schemas without primary key

[fuelen]

handles a case when embedded schema struct belongs to normal record, like

User
  embeds_one(:address, Address)

Address
  belongs_to(:country, Country)

[fuelen]

@benwilson512 please let me know whether this approach OK, and you're ready to merge it, so I could add some tests

[benwilson512]

Hi @fuelen can you elaborate a bit more? What sort of Dataloader.load call does this help with?

[fuelen]

Hi @benwilson512
Sure 🙂

If we talk in terms of the schema example above, then I do the following GraphQL query

{
  users {
    address {
      country { name }
    }
}

the :address object is defined like this

object :address do
  field(:country, :country, resolve: dataloader(MyApp.Geography))
end

nothing special, the resolution of :country field is completely handled by dataloader, no custom options.

Let's say we have 2 users. One user doesn't have set a country in his address (country_id is null). I want to remind, that Address is an embedded schema. Because of this, primary key for embedded schema that doesn't have primary keys is always []. It means that [] will be used as an id for all Address structs. So, all addresses will fetch the same country. I noticed, that the first write wins, and depending on the order, all users will have the same country from DB or NULL.

[fuelen]

Hey @benwilson512
Could you look into this?

[benwilson512]

Hi @fuelen this seems fine, please just add a test.

[fuelen]

Added a test

[fuelen]

Hi @benwilson512
Could you merge this PR? 🙂

[benwilson512]

Thanks!