ash v0.11.0 Ash.Changeset View Source

Changesets are used to create and update data in Ash.

Create a changeset with create/2 or update/2, and alter the attributes and relationships using the functions provided in this module. Nothing in this module actually incurs changes in a data layer. To commit a changeset, see Ash.Api.create/2 and Ash.Api.update/2.

Primary Keys

For relationship manipulation using append_to_relationship/3, remove_from_relationship/3 and replace_relationship/3 there are three types that can be used for primary keys:

1.) An instance of the resource in question.

2.) If the primary key is just a single field, i.e :id, then a single value, i.e 1

3.) A map of keys to values representing the primary key, i.e %{id: 1} or %{id: 1, org_id: 2}

Join Attributes

For many to many relationships, the attributes on a join relationship may be set while relating items by passing a tuple of the primary key and the changes to be applied. This is done via upserts, so update validations on the join resource are not applied, but create validations are.

For example:

Ash.Changeset.replace_relationship(changeset, :linked_tickets, [
  {1, %{link_type: "blocking"}},
  {a_ticket, %{link_type: "caused_by"}},
  {%{id: 2}, %{link_type: "related_to"}}
])

Link to this section Summary

Types

t()

Functions

add_error(changeset, error)

Adds an error to the changesets errors list, and marks the change as valid?: false

after_action(changeset, func)

Adds an after_action hook to the changeset.

append_to_relationship(changeset, relationship, record_or_records)

Appends a record of list of records to a relationship. Stacks with previous removals/additions.

apply_attributes(changeset)

Returns the original data with attribute changes merged.

before_action(changeset, func)

Adds a before_action hook to the changeset.

change_attribute(changeset, attribute, value)

Adds a change to the changeset, unless the value matches the existing value

change_attributes(changeset, changes)

Calls change_attribute/3 for each key/value pair provided

change_new_attribute(changeset, attribute, value)

Change an attribute only if is not currently being changed

change_new_attribute_lazy(changeset, attribute, func)

Change an attribute if is not currently being changed, by calling the provided function

changing_attribute?(changeset, attribute)

Returns true if an attribute exists in the changes

fetch_change(changeset, attribute)

Gets the new value for an attribute, or :error if it is not being changed

force_change_attribute(changeset, attribute, value)

Changes an attribute even if it isn't writable

force_change_attributes(changeset, changes)

Calls force_change_attribute/3 for each key/value pair provided

get_attribute(changeset, attribute)

Gets the changing value or the original value of an attribute

get_data(changeset, attribute)

Gets the original value for an attribute

new(resource, initial_attributes \\ %{})

Return a changeset over a resource or a record

remove_from_relationship(changeset, relationship, record_or_records)

Removes a record of list of records to a relationship. Stacks with previous removals/additions.

replace_relationship(changeset, relationship, record_or_records)

Replaces the value of a relationship. Any previous additions/removals are cleared.

with_hooks(changeset, func)

Wraps a function in the before/after action hooks of a changeset.

Link to this section Types

t()

Specs

t() :: %Ash.Changeset{
  action_type: term(),
  after_action: term(),
  api: term(),
  attributes: term(),
  before_action: term(),
  change_dependencies: term(),
  data: term(),
  errors: term(),
  relationships: term(),
  requests: term(),
  resource: term(),
  valid?: term()
}

Link to this section Functions

add_error(changeset, error)

Specs

add_error(t(), Ash.error()) :: t()

Adds an error to the changesets errors list, and marks the change as valid?: false

after_action(changeset, func)

Specs

after_action(t(), (t(), Ash.record() -> {:ok, Ash.record()} | {:error, term()})) ::
  t()

Adds an after_action hook to the changeset.

append_to_relationship(changeset, relationship, record_or_records)

Specs

append_to_relationship(t(), atom(), Ash.primary_key() | [Ash.primary_key()]) ::
  t()

Appends a record of list of records to a relationship. Stacks with previous removals/additions.

Accepts a primary key or a list of primary keys. See the section on "Primary Keys" in the module documentation for more.

For many to many relationships, accepts changes for any join_attributes configured on the resource. See the section on "Join Attributes" in the module documentation for more.

Cannot be used with belongs_to or has_one relationships. See replace_relationship/3 for manipulating belongs_to and has_one relationships.

apply_attributes(changeset)

Specs

apply_attributes(t()) :: Ash.record()

Returns the original data with attribute changes merged.

before_action(changeset, func)

Specs

before_action(t(), (t() -> t())) :: t()

Adds a before_action hook to the changeset.

change_attribute(changeset, attribute, value)

Adds a change to the changeset, unless the value matches the existing value

change_attributes(changeset, changes)

Specs

change_attributes(t(), map() | Keyword.t()) :: t()

Calls change_attribute/3 for each key/value pair provided

change_new_attribute(changeset, attribute, value)

Specs

change_new_attribute(t(), atom(), term()) :: t()

Change an attribute only if is not currently being changed

change_new_attribute_lazy(changeset, attribute, func)

Specs

change_new_attribute_lazy(t(), atom(), (() -> any())) :: t()

Change an attribute if is not currently being changed, by calling the provided function

Use this if you want to only perform some expensive calculation for an attribute value only if there isn't already a change for that attribute

changing_attribute?(changeset, attribute)

Specs

changing_attribute?(t(), atom()) :: boolean()

Returns true if an attribute exists in the changes

fetch_change(changeset, attribute)

Specs

fetch_change(t(), atom()) :: {:ok, any()} | :error

Gets the new value for an attribute, or :error if it is not being changed

force_change_attribute(changeset, attribute, value)

Specs

force_change_attribute(t(), atom(), any()) :: t()

Changes an attribute even if it isn't writable

force_change_attributes(changeset, changes)

Specs

force_change_attributes(t(), map()) :: t()

Calls force_change_attribute/3 for each key/value pair provided

get_attribute(changeset, attribute)

Specs

get_attribute(t(), atom()) :: term()

Gets the changing value or the original value of an attribute

get_data(changeset, attribute)

Specs

get_data(t(), atom()) :: {:ok, any()} | :error

Gets the original value for an attribute

new(resource, initial_attributes \\ %{})

Specs

new(Ash.resource() | Ash.record(), map()) :: t()

Return a changeset over a resource or a record

remove_from_relationship(changeset, relationship, record_or_records)

Specs

remove_from_relationship(t(), atom(), Ash.primary_key() | [Ash.primary_key()]) ::
  t()

Removes a record of list of records to a relationship. Stacks with previous removals/additions.

Accepts a primary key or a list of primary keys. See the section on "Primary Keys" in the module documentation for more.

Cannot be used with belongs_to or has_one relationships. See replace_relationship/3 for manipulating those relationships.

replace_relationship(changeset, relationship, record_or_records)

Specs

replace_relationship(t(), atom(), Ash.primary_key() | [Ash.primary_key()]) ::
  t()

Replaces the value of a relationship. Any previous additions/removals are cleared.

Accepts a primary key or a list of primary keys. See the section on "Primary Keys" in the module documentation for more.

For many to many relationships, accepts changes for any join_attributes configured on the resource. See the section on "Join Attributes" in the module documentation for more.

For a has_many or many_to_many relationship, this means removing any currently related records that are not present in the replacement list, and creating any that do not exist in the data layer.

For a belongs_to or has_one, replace with a nil value to unset a relationship.

with_hooks(changeset, func)

Specs

with_hooks(t(), (t() -> {:ok, Ash.record()} | {:error, term()})) ::
  {:ok, term()} | {:error, term()}

Wraps a function in the before/after action hooks of a changeset.

The function takes a changeset and if it returns {:ok, result}, the result will be passed through the after action hooks.