View Source EctoDiscriminator.DiscriminatorType (ecto_discriminator v0.4.3)
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 fromSchema
.
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
.
Link to this section Summary
Functions
Callback implementation for Ecto.Type.cast/1
.
Callback implementation for Ecto.Type.dump/1
.
Callback implementation for Ecto.Type.embed_as/1
.
Callback implementation for Ecto.Type.equal?/2
.
Callback implementation for Ecto.Type.load/1
.
Callback implementation for Ecto.Type.type/0
.
Link to this section Functions
Callback implementation for Ecto.Type.cast/1
.
Callback implementation for Ecto.Type.dump/1
.
Callback implementation for Ecto.Type.embed_as/1
.
Callback implementation for Ecto.Type.equal?/2
.
Callback implementation for Ecto.Type.load/1
.
Callback implementation for Ecto.Type.type/0
.