View Source Ash.Type behaviour (ash v2.9.21)

Describes how to convert data to Ecto.Type and eventually into the database.

This behaviour is a superset of the Ecto.Type behaviour, that also contains API level information, like what kinds of filters are allowed.

built-in-types

Built in types

composite-types

Composite Types

Currently, the only composite type supported is a list type, specified via: {:array, Type}. The constraints available are:

  • :items (term/0) - Constraints for the elements of the list. See the contained type's docs for more.

  • :min_length (non_neg_integer/0) - A minimum length for the items

  • :max_length (non_neg_integer/0) - A maximum length for the items

  • :nil_items? (boolean/0) - Whether or not the list can contain nil items The default value is false.

  • :empty_values (list of term/0) - A set of values that, if encountered, will be considered an empty list. The default value is [""].

defining-custom-types

Defining Custom Types

Generally you add use Ash.Type to your module (it is possible to add @behaviour Ash.Type and define everything yourself, but this is more work and error-prone).

Overriding the {:array, type} behaviour. By defining the *_array versions of cast_input, cast_stored, dump_to_native and apply_constraints, you can override how your type behaves as a collection. This is how the features of embedded resources are implemented. No need to implement them unless you wish to override the default behaviour.

Simple example of a float custom type

defmodule GenTracker.AshFloat do
  use Ash.Type

  @impl Ash.Type
  def storage_type, do: :float

  @impl Ash.Type
  def cast_input(value, _) do
    Ecto.Type.cast(:float, value)
  end

  @impl Ash.Type
  def cast_stored(value, _) do
    Ecto.Type.load(:float, value)
  end

  @impl Ash.Type
  def dump_to_native(value, _) do
    Ecto.Type.dump(:float, value)
  end
end

All the Ash built-in types are implemented with use Ash.Type so they are good examples to look at to create your own Ash.Type.

short-names

Short names

You can define short :atom_names for your custom types by adding them to your Ash configuration:

config :ash, :custom_types, [ash_float: GenTracker.AshFloat]

Doing this will require a recompilation of the :ash dependency which can be triggered by calling:

$ mix deps.compile ash --force

Link to this section Summary

Functions

Confirms if a casted value matches the provided constraints.

Returns true if the value is a builtin type or adopts the Ash.Type behaviour

Casts input (e.g. unknown) data to an instance of the type, or errors

Casts a value from the data store to an instance of the type, or errors

Casts a value from the Elixir type to a value that can be embedded in another data structure.

Casts a value from the Elixir type to a value that the data store can persist

Returns the ecto compatible type for an Ash.Type.

Determines if two values of a given type are equal.

Process the old casted values alongside the new casted values.

Process the old casted values alongside the new uncasted values.

Determines if a type can be compared using ==

Returns the underlying storage type (the underlying type of the ecto type of the ash type)

Link to this section Types

@type constraint_error() :: String.t() | {String.t(), Keyword.t()}
@type constraints() :: Keyword.t()
@type error() :: :error | {:error, String.t() | Keyword.t()}
@type t() :: atom() | {:array, atom()}

Link to this section Callbacks

Link to this callback

apply_constraints(term, constraints)

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@callback apply_constraints(term(), constraints()) ::
  {:ok, new_value :: term()}
  | :ok
  | {:error, constraint_error() | [constraint_error()]}
Link to this callback

apply_constraints_array(list, constraints)

View Source (optional)
@callback apply_constraints_array([term()], constraints()) ::
  {:ok, new_values :: [term()]}
  | :ok
  | {:error, constraint_error() | [constraint_error()]}
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array_constraints()

View Source (optional)
@callback array_constraints() :: constraints()
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cast_in_query?(constraints)

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@callback cast_in_query?(constraints()) :: boolean()

Useful for typed data layers (like ash_postgres) to instruct them not to attempt to cast input values.

You generally won't need this, but it can be an escape hatch for certain cases.

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cast_input(term, constraints)

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@callback cast_input(term(), constraints()) :: {:ok, term()} | error()
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cast_input_array(list, constraints)

View Source (optional)
@callback cast_input_array([term()], constraints()) :: {:ok, [term()]} | error()
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cast_stored(term, constraints)

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@callback cast_stored(term(), constraints()) :: {:ok, term()} | error()
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cast_stored_array(list, constraints)

View Source (optional)
@callback cast_stored_array([term()], constraints()) :: {:ok, [term()]} | error()
@callback constraints() :: constraints()
@callback describe(constraints()) :: String.t() | nil
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dump_to_embedded(term, constraints)

View Source (optional)
@callback dump_to_embedded(term(), constraints()) :: {:ok, term()} | :error
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dump_to_embedded_array(list, constraints)

View Source (optional)
@callback dump_to_embedded_array([term()], constraints()) :: {:ok, term()} | error()
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dump_to_native(term, constraints)

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@callback dump_to_native(term(), constraints()) :: {:ok, term()} | error()
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dump_to_native_array(list, constraints)

View Source (optional)
@callback dump_to_native_array([term()], constraints()) :: {:ok, term()} | error()
@callback ecto_type() :: Ecto.Type.t()
@callback embedded?() :: boolean()
@callback equal?(term(), term()) :: boolean()
Link to this callback

generator(constraints)

View Source (optional)
@callback generator(constraints()) :: Enumerable.t()
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handle_change(old_term, new_term, constraints)

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@callback handle_change(old_term :: term(), new_term :: term(), constraints()) ::
  {:ok, term()} | error()
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handle_change_array(old_term, new_term, constraints)

View Source (optional)
@callback handle_change_array(old_term :: [term()], new_term :: [term()], constraints()) ::
  {:ok, term()} | error()
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prepare_change(old_term, new_uncasted_term, constraints)

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@callback prepare_change(old_term :: term(), new_uncasted_term :: term(), constraints()) ::
  {:ok, term()} | error()
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prepare_change_array( old_term, new_uncasted_term, constraints )

View Source (optional)
@callback prepare_change_array(
  old_term :: [term()],
  new_uncasted_term :: [term()],
  constraints()
) :: {:ok, term()} | error()
@callback simple_equality?() :: boolean()
@callback storage_type() :: Ecto.Type.t()

Link to this section Functions

Link to this function

apply_constraints(type, term, constraints)

View Source
@spec apply_constraints(t(), term(), constraints()) ::
  {:ok, term()} | {:error, String.t()}

Confirms if a casted value matches the provided constraints.

@spec ash_type?(term()) :: boolean()

Returns true if the value is a builtin type or adopts the Ash.Type behaviour

Link to this function

cast_in_query?(type, constraints \\ [])

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Link to this function

cast_input(type, term, constraints \\ [])

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@spec cast_input(t(), term(), constraints() | nil) ::
  {:ok, term()} | {:error, Keyword.t()} | :error

Casts input (e.g. unknown) data to an instance of the type, or errors

Maps to Ecto.Type.cast/2

Link to this function

cast_stored(type, term, constraints \\ [])

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@spec cast_stored(t(), term(), constraints() | nil) ::
  {:ok, term()} | {:error, keyword()} | :error

Casts a value from the data store to an instance of the type, or errors

Maps to Ecto.Type.load/2

@spec constraints(t()) :: constraints()
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constraints(source, type, constraints)

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@spec constraints(Ash.Changeset.t() | Ash.Query.t(), t(), Keyword.t()) :: Keyword.t()
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describe(type, constraints)

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dump_to_embedded(type, term, constraints \\ [])

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@spec dump_to_embedded(t(), term(), constraints() | nil) ::
  {:ok, term()} | {:error, keyword()} | :error

Casts a value from the Elixir type to a value that can be embedded in another data structure.

Embedded resources expect to be stored in JSON, so this allows things like UUIDs to be stored as strings in embedded resources instead of binary.

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dump_to_native(type, term, constraints \\ [])

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@spec dump_to_native(t(), term(), constraints() | nil) ::
  {:ok, term()} | {:error, keyword()} | :error

Casts a value from the Elixir type to a value that the data store can persist

Maps to Ecto.Type.dump/2

@spec ecto_type(t()) :: Ecto.Type.t()

Returns the ecto compatible type for an Ash.Type.

If you use Ash.Type, this is created for you. For builtin types this may return a corresponding ecto builtin type (atom)

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equal?(type, left, right)

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@spec equal?(t(), term(), term()) :: boolean()

Determines if two values of a given type are equal.

Maps to Ecto.Type.equal?/3

Link to this function

generator(type, constraints)

View Source
@spec generator(
  module() | {:array, module()},
  constraints()
) :: Enumerable.t()
@spec get_type(atom() | module() | {:array, atom() | module()}) ::
  atom() | module() | {:array, atom() | module()}
Link to this function

handle_change(type, old_value, new_value, constraints)

View Source

Process the old casted values alongside the new casted values.

This is leveraged by embedded types to know if something is being updated or destroyed. This is not called on creates.

Link to this function

prepare_change(type, old_value, new_value, constraints)

View Source

Process the old casted values alongside the new uncasted values.

This is leveraged by embedded types to know if something is being updated or destroyed. This is not called on creates.

@spec simple_equality?(t()) :: boolean()

Determines if a type can be compared using ==

@spec storage_type(t()) :: Ecto.Type.t()

Returns the underlying storage type (the underlying type of the ecto type of the ash type)