Ash Elixir•3y ago

Nested form with filtered subform elements

Let's say there is a nested form with Tweet as the main and Comment as the sub. The requirement is to only show and make editable the comments entered by the current user in the subform. I'm hoping to accomplish this without using CSS tricks of hiding other users' comments. By loading filtered records into the form using the code below, I was able to make the form look like what I want, but when I submit the form, comments previously made by other users (apparently, filtered out from the form) seem to be removed. Is this the expected behavior of a nested form? Is there a relatively easy way to make it save the change without removing other users' comments?

  def tweet_load(current_user) do
    comments=
      Comment
      |> Ash.Query.filter(user_id == ^current_user.id)

    tweets=
      Tweet
      |> Ash.Query.sort(row_order: :asc)
      |> Ash.Query.load([     
        comments: comments
      ])

  def tweet_load(current_user) do
    comments=
      Comment
      |> Ash.Query.filter(user_id == ^current_user.id)

    tweets=
      Tweet
      |> Ash.Query.sort(row_order: :asc)
      |> Ash.Query.load([     
        comments: comments
      ])

7 Replies

JasonOP•3y ago

I'm guessing one way to do this is by defining a clever create/update action to handle the comment_form, but wanted to ask here first, in case I'm missing something easier.

ZachDaniel•3y ago

🤔 there are ways to do this, but it might be a bit complex no matter how you cut it. What I would suggest is essentially "rolling your own" by using the ignore?: true option to manage_relationship

change manage_relationship(:name, ...., ignore?: true)

change manage_relationship(:name, ...., ignore?: true)

What that does is communicate to things like AshPhoenix.Form that you manage that relationship in a similar way w/ similar semantics, but you'll handle the inputs yourself Then:

change fn changeset, %{actor: actor} ->
  Ash.Changeset.before_action(changeset, fn changeset -> 
    inputs = changeset.arguments[:arg_name] || []
    ids = inputs |> Enum.map(&(&1[:id] || &1["id"])) |> Enum.reject(&is_nil/1)
  # use some manual ecto for bulk delete since we don't have bulk delete yet
    removed_comments =
      from row in Related,
        where: user_id == ^actor.id,
        where: id not in ids

    MyApp.Repo.delete_all(removed_comments)

    Enum.each(inputs, fn input -> 
      # upsert related resources by id
    end)
  end)
end

change fn changeset, %{actor: actor} ->
  Ash.Changeset.before_action(changeset, fn changeset -> 
    inputs = changeset.arguments[:arg_name] || []
    ids = inputs |> Enum.map(&(&1[:id] || &1["id"])) |> Enum.reject(&is_nil/1)
  # use some manual ecto for bulk delete since we don't have bulk delete yet
    removed_comments =
      from row in Related,
        where: user_id == ^actor.id,
        where: id not in ids

    MyApp.Repo.delete_all(removed_comments)

    Enum.each(inputs, fn input -> 
      # upsert related resources by id
    end)
  end)
end

JasonOP•3y ago

Thank you!! Tried this code for changing attribute of the form input manually with the value from the changeset attribute. When the form is validated the first inspect message is printed, but neither message is printed when the form is submitted, which leads me to believe this update action isn't being triggered upon form submission. What could I be missing?

defmodule RollOwnUpdate do
  use Ash.Resource.Change

  def change(changeset, opts, %{actor: actor}) do
    IO.inspect("before before_action ################")  ## This prints

    Ash.Changeset.before_action(changeset, fn changeset ->
      IO.inspect(changeset.argument[:comment],   ## This doesn't.
        label: "inside before_action ###########"
      )

      comment = MyApp.Comment.get_by_id!(changeset.data.id)
      changeset = comment |> Ash.Changeset.new()

      Ash.Changeset.change_attribute(
        changeset,
        :comment,
        Ash.Changeset.get_attribute(changeset, :comment)
      )
      |> IO.inspect(label: "changeset in update ###########")
      |> MyApp.Comment.update()
    end)
  end
end

defmodule RollOwnUpdate do
  use Ash.Resource.Change

  def change(changeset, opts, %{actor: actor}) do
    IO.inspect("before before_action ################")  ## This prints

    Ash.Changeset.before_action(changeset, fn changeset ->
      IO.inspect(changeset.argument[:comment],   ## This doesn't.
        label: "inside before_action ###########"
      )

      comment = MyApp.Comment.get_by_id!(changeset.data.id)
      changeset = comment |> Ash.Changeset.new()

      Ash.Changeset.change_attribute(
        changeset,
        :comment,
        Ash.Changeset.get_attribute(changeset, :comment)
      )
      |> IO.inspect(label: "changeset in update ###########")
      |> MyApp.Comment.update()
    end)
  end
end

ignore? true was added to the update action of Tweet resource. like this.

argument :comments, {:array, :map}
      change manage_relationship(:comments, type: :direct_control, ignore?: true)

argument :comments, {:array, :map}
      change manage_relationship(:comments, type: :direct_control, ignore?: true)

    update :update_current_user_comment_only do
      IO.inspect("####update entered4######")  ## This doesn't print

      change RollOwnUpdate
    end

    update :update_current_user_comment_only do
      IO.inspect("####update entered4######")  ## This doesn't print

      change RollOwnUpdate
    end

Here is the form definition in the mount function of the liveview.

        forms: [
          tweets: [
            resource: Tweet,
            data: tweets,
            create_action: :create,
            update_action: :update,
            type: :list,
            forms: [
              comments: [
                resource: Comment,
                data: & &1.comments,
                create_action: :create,
                update_action: :update_current_user_comment_only,
                type: :list
              ]
            ]

        forms: [
          tweets: [
            resource: Tweet,
            data: tweets,
            create_action: :create,
            update_action: :update,
            type: :list,
            forms: [
              comments: [
                resource: Comment,
                data: & &1.comments,
                create_action: :create,
                update_action: :update_current_user_comment_only,
                type: :list
              ]
            ]

ZachDaniel•3y ago

could you have a different error happening somewhere? The before action hooks are only called on valid changesets.

JasonOP•3y ago

The fact that the inspect message in the update action doesn't print makes me think that something is off in the way I trigger the action when the form is submitted.

ZachDaniel•3y ago

Oh, thats not how that works really that update code block is evaluated once at compile time so you'll never see that

JasonOP•3y ago

my bad.. yeah, I shouldn't have expected the inspect line in the update action to print.

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Nested form with filtered subform elements

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