Ash Elixir•3y ago

Nested form example

While applying the example on this page to my project, https://ash-hq.org/docs/module/ash_phoenix/latest/ashphoenix-form, I ran into this error.

no case clause matching: [#Tweets.Item<...

no case clause matching: [#Tweets.Item<...

Can you please give me some pointers? <my code in TweetEdit>

    form =
      AshPhoenix.Form.for_update(tweet, :update,  <<<< line 21
        api: Tweets,
        forms: [
          items: [
            resource: Item,
            data: tweet.items,
            create_action: :create,
            update_action: :update
          ]

    form =
      AshPhoenix.Form.for_update(tweet, :update,  <<<< line 21
        api: Tweets,
        forms: [
          items: [
            resource: Item,
            data: tweet.items,
            create_action: :create,
            update_action: :update
          ]

<lib/ashphoenix/form/form.ex> `` import AshPhoenix.FormData.Helpers @doc "Calls the correspondingfor*` function depending on the action type" def for_action(resource_or_data, action, opts) do {resource, data} = case resource_or_data do module when is_atom(resource_or_data) -> {module, module.struct()} %resource{} = data -> {resource, data} end

<stacktrace>

<stacktrace>

ash_phoenix lib/ash_phoenix/form/form.ex:379 AshPhoenix.Form.for_action/3 ash_phoenix lib/ash_phoenix/form/form.ex:3480 AshPhoenix.Form.handle_form_without_params/13 elixir lib/enum.ex:2468 Enum."-reduce/3-lists^foldl/2-0-"/3 ash_phoenix lib/ash_phoenix/form/form.ex:538 AshPhoenix.Form.for_update/3 lib/tweet_web/live/tweet_live/tweet_edit.ex:21 TweetLive.TweetEdit.mount/3 ```

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Guide: Getting Started With Ash And Phoenix

Read the "Getting Started With Ash And Phoenix" guide on Ash HQ

22 Replies

ZachDaniel•3y ago

Add type: :list to the configuration of items Looks like that isn’t shown in the examples.

JasonOP•3y ago

Thank you! Now I'm getting Invalid or non-existent path errors when I click on the add buttons. It's possible I'm not understanding the example code in the said documentation. In the leex template below, if I click the Add Tweet button, I get Invalid or non-existent path: [] for the Add Item button, I get Invalid or non-existent path: [:items, 0] <leex>

  <%= f = form_for @form, "#", [phx_change: :validate, phx_submit: :save] %>
        <%= label f, :tweet_name %>
        <%= text_input f, :tweet_name %>
        <%= f.name %>

        <div class="my-10">
        <%= for item_form <- inputs_for(f, :items) do %>
          <div class="mt-3">
            <%= hidden_inputs_for(item_form) %>
            <%= text_input item_form, :item_name %>
            <%= text_input item_form, :item_count %>
            <%= item_form.name %>  ### This prints `form[items][0]`
          </div>
          <button phx-click="remove_form" phx-value-path="<%= item_form.name %>">Remove item</button>
          <button phx-click="add_form" phx-value-path="<%= item_form.name %>">Add item</button>
        <% end %>
        </div>

        <div>
        <button phx-click="add_form" phx-value-path="<%= f.name %>">Add Tweet</button>

        <span>
        <%= submit "Save" %>
        </span>
        </div>
      </form>

  <%= f = form_for @form, "#", [phx_change: :validate, phx_submit: :save] %>
        <%= label f, :tweet_name %>
        <%= text_input f, :tweet_name %>
        <%= f.name %>

        <div class="my-10">
        <%= for item_form <- inputs_for(f, :items) do %>
          <div class="mt-3">
            <%= hidden_inputs_for(item_form) %>
            <%= text_input item_form, :item_name %>
            <%= text_input item_form, :item_count %>
            <%= item_form.name %>  ### This prints `form[items][0]`
          </div>
          <button phx-click="remove_form" phx-value-path="<%= item_form.name %>">Remove item</button>
          <button phx-click="add_form" phx-value-path="<%= item_form.name %>">Add item</button>
        <% end %>
        </div>

        <div>
        <button phx-click="add_form" phx-value-path="<%= f.name %>">Add Tweet</button>

        <span>
        <%= submit "Save" %>
        </span>
        </div>
      </form>

ZachDaniel•3y ago

Ah, yeah so that’s not how you’d add a form. That form’s name includes the index. You’d want something like phx-click=add-item And then in the add item handler you’d use add_form(form, :items) For top level forms it’s pretty simple. But for multiply nested forms you’d do parent_form.name <> “[items]”

JasonOP•3y ago

Thank you! I was able to get the form validation to work such that a new item entered by add_item was included in the form's params. Form submission, though it returned an ok tuple, didn't persist the new item in the database, and I realized I need to add manage_relationship to the parent (Tweet) resource's update action

, which I did like this.

<tweet.ex>
```
update :update do
      ...
      argument :items, {:array, :map}
      change manage_relationship(:items, type: :update)

relationships do
    has_many :items, MyApp.Tweets.Item
  end
```
Then it gave me this error as soon as the app started. What am I missing?

```
** (EXIT from #PID<0.104.0>) an exception was raised:
    ** (Spark.Error.DslError) [MyApp.Tweets.tweet]
 actions -> update -> update -> change -> manage_relationship -> items:
  The following error was raised when validating options provided to manage_relationship.

** (FunctionClauseError) no function clause matching in Ash.Changeset.manage_relationship_opts/1
    (ash 2.6.10) lib/ash/changeset/changeset.ex:2010: Ash.Changeset.manage_relationship_opts(:update)
    (ash 2.6.10) lib/ash/resource/transformers/validate_manage_relationship_opts.ex:68: anonymous fn/3 in Ash.Resource.Transformers.ValidateManagedRelationshipOpts.transform/1
    (elixir 1.14.1) lib/enum.ex:975: Enum."-each/2-lists^foreach/1-0-"/2
    (ash 2.6.10) lib/ash/resource/transformers/validate_manage_relationship_opts.ex:19: Ash.Resource.Transformers.ValidateManagedRelationshipOpts.transform/1
    (spark 0.4.5) lib/spark/dsl/extension.ex:563: anonymous fn/4 in Spark.Dsl.Extension.run_transformers/4
    (elixir 1.14.1) lib/enum.ex:4751: Enumerable.List.reduce/3
    (elixir 1.14.1) lib/enum.ex:2514: Enum.reduce_while/3
    (elixir 1.14.1) lib/enum.ex:975: Enum."-each/2-lists^foreach/1-0-"/2
```
The

form definition in the mount` function looks like this.

 form =
      AshPhoenix.Form.for_update(tweet, :update,
        api: MyApp.Tweets,
        forms: [
            items: [
            resource: Item,
            data: tweet.items,
            create_action: :create,
            update_action: :update,
            type: :list
          ]

 form =
      AshPhoenix.Form.for_update(tweet, :update,
        api: MyApp.Tweets,
        forms: [
            items: [
            resource: Item,
            data: tweet.items,
            create_action: :create,
            update_action: :update,
            type: :list
          ]

ZachDaniel•3y ago

:update is not a valid type What do you want to happen with the given items? Should it essentially replace the relationship in its entirety? deleting any thing that is missing, adding new things, and updating any currently related things? If so, then you want type: :direct_control

JasonOP•3y ago

Thank you! That did the trick. 🙂 I have a follow up question. When a nested form is validated, Ash.Changeset.before_action idoesn't seem to behave the way I expected. In the above example, Tweet's update action triggers Item's update action through change manage_relationship(:items, type: direct_control). Item's update action happens to have a custom change module like this

 change {RequireValidItemCount, []}

 change {RequireValidItemCount, []}

which is defined as

defmodule RequireValidItemCount do
  use Ash.Resource.Change
  
  def change(changeset, opts, %{actor: actor}) do
    IO.puts("print 1")
    Ash.Changeset.before_action(changeset, fn changeset ->
      IO.puts("print 2")
      item_count = Ash.Changeset.get_argument(changeset, :item_count)

      if item_count <= 4 do
       changeset
      else
        Ash.Changeset.add_error(changeset,
          field: :item_count,
          message: "This is invalid count."
        )
      end
    end)
  end
end

defmodule RequireValidItemCount do
  use Ash.Resource.Change
  
  def change(changeset, opts, %{actor: actor}) do
    IO.puts("print 1")
    Ash.Changeset.before_action(changeset, fn changeset ->
      IO.puts("print 2")
      item_count = Ash.Changeset.get_argument(changeset, :item_count)

      if item_count <= 4 do
       changeset
      else
        Ash.Changeset.add_error(changeset,
          field: :item_count,
          message: "This is invalid count."
        )
      end
    end)
  end
end

When item_count is changed in a nested form, this RequireValidItemCount is not validated. Interestingly, print 1 is printed, but not print 2 which means the validation flow reachesRequireValidItemCount but the Ash.Changeset.before_action block doesn't run. If I update Item directly like item |> Ash.Changeset.for_update ... RequireValidItemCount does its job just fine. How do I make Ash.Changeset.before_action work through manage_relationship?

ZachDaniel•3y ago

Before action hooks are not called until the actual action is invoked (i.e the form is submitted) as that is their purpose(to delay things until the action lifecycle).

JasonOP•3y ago

Got it. Thanks. Is there an example of custom validation?

ZachDaniel•3y ago

In that case, you should be able to do validate compare(:item_count, greater_than_or_equal_to: 4) You can put that in an individual action:

actions do
  create :create do
    ...
    validate ...
  end
end

actions do
  create :create do
    ...
    validate ...
  end
end

or for all actions

validations do
  validate ....
end

validations do
  validate ....
end

JasonOP•3y ago

Yeah, I tried it and it worked perfectly. I just wanted to know how to write the same using customer module in case it comes in handy.

ZachDaniel•3y ago

Ah, gotcha

ZachDaniel•3y ago

https://github.com/ash-project/ash/blob/v2.6.20/lib/ash/resource/validation/builtins.ex#L239

GitHub

ash/builtins.ex at v2.6.20 · ash-project/ash

A declarative and extensible framework for building Elixir applications. - ash/builtins.ex at v2.6.20 · ash-project/ash

ZachDaniel•3y ago

So all of the built in validations are technically custom validations They are just provided with convenient function names like compare/1

ZachDaniel•3y ago

So the compare/2 validation's implementation is here: https://github.com/ash-project/ash/blob/v2.6.20/lib/ash/resource/validation/compare.ex

GitHub

ash/compare.ex at v2.6.20 · ash-project/ash

A declarative and extensible framework for building Elixir applications. - ash/compare.ex at v2.6.20 · ash-project/ash

ZachDaniel•3y ago

Naturally, though, the built in ones are a bit more involved because they cover all kinds of cases.

JasonOP•3y ago

I see. And to use it in a resource is something like this? Apparently this doesn't seem to work.

  validations do
    validate {RequireValidItemCount, []} do
      message: "Item count must be greater than 0"
    end
  end

  validations do
    validate {RequireValidItemCount, []} do
      message: "Item count must be greater than 0"
    end
  end

ZachDaniel•3y ago

  validations do
    validate {RequireValidItemCount, []} do
      message "Item count must be greater than 0"
    end
  end

  validations do
    validate {RequireValidItemCount, []} do
      message "Item count must be greater than 0"
    end
  end

RequireValidItemCount needs to be an Ash.Resource.Validation as well and then you can also return the message from the validation directly {:error, "Item count must be greater than 0"}

JasonOP•3y ago

Okay. Still digesting the compare example for that. one sec. I thought this would work as a minimalistic example, but it doesn't. What am I missing?

defmodule RequireValidItemCount do
  use Ash.Resource.Validation

  @impl true
  def validate(changeset, opts) do
    item_count = Ash.Changeset.get_attribute(changeset, :item_count)

    if item_count <= 4 do
      :ok
    else
      {:error, "This is more than needed."}
    end
  end
end

defmodule RequireValidItemCount do
  use Ash.Resource.Validation

  @impl true
  def validate(changeset, opts) do
    item_count = Ash.Changeset.get_attribute(changeset, :item_count)

    if item_count <= 4 do
      :ok
    else
      {:error, "This is more than needed."}
    end
  end
end

I'm guessing invalid attribute error is needed in the error tuple?

ZachDaniel•3y ago

That looks like it should work just fine really When you say it doesn't work, why not? Do you mean its not showing up in your form?

JasonOP•3y ago

No error message in the form. Right.

ZachDaniel•3y ago

{:error, message: "This is more than needed.", field: :item_count}

{:error, message: "This is more than needed.", field: :item_count}

SO yes an invalid attribute error would also have done it

{:error, Ash.Error.Invalid.InvalidAttribute.exception(field: :item_count, message: "This is more than needed.")}

{:error, Ash.Error.Invalid.InvalidAttribute.exception(field: :item_count, message: "This is more than needed.")}

JasonOP•3y ago

Yay! It's working. Thank you!!

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