A custom type used by the EctoDiscriminator.Schema to know which field should be used for its logic.

schema

Schema

EctoDiscriminator.DiscriminatorType field holds name of the diverged module. Field name can be anything. User has to mark exactly one field in the base schema with this type. Diverged schemas will inherit this setting. Forgetting to add this field will result in compilation error. Basic setup:

field :type, EctoDiscriminator.DiscriminatorType

You can also use it as a primary key:

@primary_key {:id, EctoDiscriminator.DiscriminatorType, []}

You can also make a virtual discriminator:

field :type, EctoDiscriminator.DiscriminatorType, virtual: true

Please note

This will keep most of the functionality intact, however it will disable where when fetching data.

This means that you can for example still preload this entity inside other schemas, but issuing Repo.all(Schema.Diverged) will return all items from Schema.

You can also configure any other options that are supported by Ecto.Schema (except default for obvious reasons).

field :discriminator, EctoDiscriminator.DiscriminatorType, load_in_query: false

migrations

Migrations

When it comes to the migrations, the underlying type is just :string. That said, it's completely fine to create migration with string field:

add :type, :string

It's possible to be more restrictive and provide an enum inside DB. Keep in mind that module name will be stored in form Elixir.Module.Name.