Ash Framework•4mo ago

manage_relationship to create another resource `belongs_to` relation

Hi, I noticed I have a pretty common thing to define an action on a resource, which will automatically created related resources that is in the scope of the action. I wanted to know how to do that declaratively Example.

Organization (has_many Member)
Member (belongs_to Organization, belongs_to User)
User (has_many Member)

Organization (has_many Member)
Member (belongs_to Organization, belongs_to User)
User (has_many Member)

I want to define a :create on Organization, that will create a member with actor Currently I am doing it in a custom function that calls

change fn changeset, context ->
  Ash.Changeset.manage_relationship(
    changeset,
    :members,
    %{user_id: context.actor.id, role: "owner"},
    type: :create
  )
end

change fn changeset, context ->
  Ash.Changeset.manage_relationship(
    changeset,
    :members,
    %{user_id: context.actor.id, role: "owner"},
    type: :create
  )
end

But I don't like this way, as there is a manage_relationship Resource action, but I don't want anything passed as arguments

Solution:

manage_relationship will eventually call a create/update action etc., and you are providing inputs for it here

Jump to solution

6 Replies

ZachDaniel•4mo ago

That's the only way currently.

VahagnOP•4mo ago

do you plan on having something like set_attribute, like set_relation? or make a duplicate of manage_relationship, which does not expect an argument, but a value?

ZachDaniel•4mo ago

No current plans, since often when you do this it's computed state for the relationship in some way There isn't anything wrong with having custom changes like that You can clean it up by putting it into a module and making it generic if you like i.e

defmodule AddMember do
  def change(changeset, opts, context) do
    Ash.Changeset.manage_relationship(
      changeset,
      :members,
      %{user_id: context.actor.id, role: opts[:role]},
      type: :create
    )
  end
end

change {AddMember, role: "owner"}

defmodule AddMember do
  def change(changeset, opts, context) do
    Ash.Changeset.manage_relationship(
      changeset,
      :members,
      %{user_id: context.actor.id, role: opts[:role]},
      type: :create
    )
  end
end

change {AddMember, role: "owner"}

If you want it to visually look the same, you can do this

def add_member(role) do
  {__MODULE__, role: role}
end

def add_member(role) do
  {__MODULE__, role: role}
end

and then in your resource

import AddMember

...

change add_member("owner")

import AddMember

...

change add_member("owner")

VahagnOP•4mo ago

Can I pass a Changeset to manage_relationship? something like

member = Member |> Ash.Changeset.for_create(:create)
Ash.Changeset.manage_relationship(changeset, :members, member, type: :create)

member = Member |> Ash.Changeset.for_create(:create)
Ash.Changeset.manage_relationship(changeset, :members, member, type: :create)

so I can define the default role for :create to be "owner"

ZachDaniel•4mo ago

No, you can only pass action inputs to the underlying action

Solution

ZachDaniel•4mo ago

manage_relationship will eventually call a create/update action etc., and you are providing inputs for it here

Gaming

Programming

manage_relationship to create another resource `belongs_to` relation

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