allow to skip persistent id generation (#3677)

Fixes #3673

Author: SteffenDE

lib/phoenix_component.ex

@@ -2711,6 +2711,14 @@ defmodule Phoenix.Component do
     """
   )
 
+  attr.(:skip_persistent_id, :boolean,
+    default: false,
+    doc: """
+    Skip the automatic rendering of hidden _persistent_id fields used for reordering
+    inputs.
+    """
+  )
+
   attr.(:options, :list,
     default: [],
     doc: """
@@ -2733,11 +2741,42 @@ defmodule Phoenix.Component do
       |> Keyword.merge(assigns.options)
 
     forms = parent_form.impl.to_form(parent_form.source, parent_form, field_name, options)
+
+    forms =
+      case assigns do
+        %{skip_persistent_id: true} ->
+          forms
+
+        _ ->
+          apply_persistent_id(
+            parent_form,
+            forms,
+            field_name,
+            options
+          )
+      end
+
+    assigns = assign(assigns, :forms, forms)
+
+    ~H"""
+    <%= for finner <- @forms do %>
+      <%= if !@skip_hidden do %>
+        <%= for {name, value_or_values} <- finner.hidden,
+                name = name_for_value_or_values(finner, name, value_or_values),
+                value <- List.wrap(value_or_values) do %>
+          <input type="hidden" name={name} value={value} />
+        <% end %>
+      <% end %>
+      {render_slot(@inner_block, finner)}
+    <% end %>
+    """
+  end
+
+  defp apply_persistent_id(parent_form, forms, field_name, options) do
     seen_ids = for f <- forms, vid = f.params[@persistent_id], into: %{}, do: {vid, true}
-    acc = {seen_ids, 0}
 
     {forms, _} =
-      Enum.map_reduce(forms, acc, fn
+      Enum.map_reduce(forms, {seen_ids, 0}, fn
         %Phoenix.HTML.Form{params: params} = form, {seen_ids, index} ->
           id =
             case params do
@@ -2766,20 +2805,7 @@ defmodule Phoenix.Component do
           {new_form, {Map.put(seen_ids, id, true), index + 1}}
       end)
 
-    assigns = assign(assigns, :forms, forms)
-
-    ~H"""
-    <%= for finner <- @forms do %>
-      <%= if !@skip_hidden do %>
-        <%= for {name, value_or_values} <- finner.hidden,
-                name = name_for_value_or_values(finner, name, value_or_values),
-                value <- List.wrap(value_or_values) do %>
-          <input type="hidden" name={name} value={value} />
-        <% end %>
-      <% end %>
-      {render_slot(@inner_block, finner)}
-    <% end %>
-    """
+    forms
   end
 
   defp next_id(idx, %{} = seen_ids) do

test/phoenix_component/components_test.exs

@@ -505,7 +505,7 @@ defmodule Phoenix.LiveView.ComponentsTest do
 
       template = ~H"""
       <.form :let={f} as={:myform}>
-        <.inputs_for :let={finner} field={f[:inner]} }>
+        <.inputs_for :let={finner} field={f[:inner]}>
           <% 0 = finner.index %>
           <input id={finner[:foo].id} name={finner[:foo].name} type="text" />
         </.inputs_for>
@@ -526,7 +526,7 @@ defmodule Phoenix.LiveView.ComponentsTest do
 
       template = ~H"""
       <.form :let={f} as={:myform}>
-        <.inputs_for :let={finner} field={f[:inner]} } id="test" as={:name}>
+        <.inputs_for :let={finner} field={f[:inner]} id="test" as={:name}>
           <input id={finner[:foo].id} name={finner[:foo].name} type="text" />
         </.inputs_for>
       </.form>
@@ -542,7 +542,7 @@ defmodule Phoenix.LiveView.ComponentsTest do
 
       template = ~H"""
       <.form :let={f} as={:myform}>
-        <.inputs_for :let={finner} field={f[:inner]} } as={:name}>
+        <.inputs_for :let={finner} field={f[:inner]} as={:name}>
           <input id={finner[:foo].id} name={finner[:foo].name} type="text" />
         </.inputs_for>
       </.form>
@@ -562,7 +562,7 @@ defmodule Phoenix.LiveView.ComponentsTest do
 
       template = ~H"""
       <.form :let={f} as={:myform}>
-        <.inputs_for :let={finner} field={f[:inner]} } default={%{foo: "123"}}>
+        <.inputs_for :let={finner} field={f[:inner]} default={%{foo: "123"}}>
           <input id={finner[:foo].id} name={finner[:foo].name} type="text" value={finner[:foo].value} />
         </.inputs_for>
       </.form>
@@ -585,7 +585,6 @@ defmodule Phoenix.LiveView.ComponentsTest do
         <.inputs_for
           :let={finner}
           field={f[:inner]}
-          }
           default={[%{foo: "456"}]}
           prepend={[%{foo: "123"}]}
           append={[%{foo: "789"}]}
@@ -613,7 +612,7 @@ defmodule Phoenix.LiveView.ComponentsTest do
 
       template = ~H"""
       <.form :let={f} as={:myform}>
-        <.inputs_for :let={finner} field={f[:inner]} } options={[foo: "bar"]}>
+        <.inputs_for :let={finner} field={f[:inner]} options={[foo: "bar"]}>
           <p>{finner.options[:foo]}</p>
         </.inputs_for>
       </.form>
@@ -623,6 +622,35 @@ defmodule Phoenix.LiveView.ComponentsTest do
       assert [p] = Floki.find(html, "p")
       assert Floki.text(p) =~ "bar"
     end
+
+    test "can disable persistent ids" do
+      assigns = %{}
+
+      template = ~H"""
+      <.form :let={f} as={:myform}>
+        <.inputs_for
+          :let={finner}
+          field={f[:inner]}
+          default={[%{foo: "456"}, %{foo: "789"}]}
+          prepend={[%{foo: "123"}]}
+          append={[%{foo: "101112"}]}
+          skip_persistent_id
+        >
+          <input id={finner[:foo].id} name={finner[:foo].name} type="text" value={finner[:foo].value} />
+        </.inputs_for>
+      </.form>
+      """
+
+      assert t2h(template) ==
+               ~X"""
+               <form>
+                 <input id="myform_inner_0_foo" name="myform[inner][0][foo]" type="text" value="123"></input>
+                 <input id="myform_inner_1_foo" name="myform[inner][1][foo]" type="text" value="456"></input>
+                 <input id="myform_inner_2_foo" name="myform[inner][2][foo]" type="text" value="789"></input>
+                 <input id="myform_inner_3_foo" name="myform[inner][3][foo]" type="text" value="101112"></input>
+               </form>
+               """
+    end
   end
 
   describe "live_file_input/1" do