add :append option to add values to the selection

lib/live_select.ex

@@ -129,9 +129,22 @@ defmodule LiveSelect do
 
   `new_selection` must be a single element in `:single` mode, a list in `:tags` mode. If it's `nil`, the selection will be cleared.  
   After updating the selection, `LiveSelect` will trigger a change event in the form.  
+  `new_selection` must be a single element in `:single` mode, a list in `:tags` mode. If it's `nil`, the selection will be cleared.
+  After updating the selection, `LiveSelect` will trigger a change event in the form.
 
   To set a custom id for the component to use with `Phoenix.LiveView.send_update/3`, you can pass the `id` assign to `live_select/1`.
 
+  ### Appending to the selection in `:tags` mode
+
+  When you want to append to the current selection, you can use the `:append` key in the `send_update` call:
+
+  ```
+  send_update(LiveSelect.Component, id: live_select_id, append: values_to_append)
+  ```
+
+  `values_to_append` can be a single element or a list to append to the current selection. If the value to append already exists in the selection, it will be ignored.
+
+  Note: This does not work in `:single` mode. Use `:value` instead to replace the selection.
 
   ## Examples
 

lib/live_select/component.ex

@@ -164,15 +164,25 @@ defmodule LiveSelect.Component do
         socket
       end
 
+
     socket =
-      if Map.has_key?(assigns, :value) do
-        update(socket, :selection, fn
-          selection, %{options: options, value: value, mode: mode, value_mapper: value_mapper} ->
-            update_selection(value, selection, options, mode, value_mapper)
-        end)
-        |> client_select(%{input_event: true})
-      else
-        socket
+      cond do
+        Map.has_key?(assigns, :value) ->
+          update(socket, :selection, fn
+            selection, %{options: options, value: value, mode: mode, value_mapper: value_mapper} ->
+              update_selection(value, selection, options, mode, value_mapper)
+          end)
+          |> client_select(%{input_event: true})
+
+        Map.has_key?(assigns, :append) ->
+          update(socket, :selection, fn
+            selection, %{append: value, mode: mode, value_mapper: value_mapper} ->
+              append_selection(value, selection, mode, value_mapper)
+          end)
+          |> client_select(%{input_event: true})
+
+        true ->
+          socket
       end
 
     {:ok, socket}
@@ -365,6 +375,7 @@ defmodule LiveSelect.Component do
           :clear_button,
           :hide_dropdown,
           :value_mapper,
+          :append,
           # for backwards compatibility
           :form
         ]
@@ -376,7 +387,7 @@ defmodule LiveSelect.Component do
           |> Enum.sort_by(&String.jaro_distance(to_string(&1), to_string(assign)))
           |> List.last()
 
-        raise ~s(Invalid assign: "#{assign}". Did you mean "#{most_similar}" ?)
+        raise ~s(Invalid assign: "#{assign}". Did you mean "#{most_similar}"?)
       end
     end
   end
@@ -527,6 +538,24 @@ defmodule LiveSelect.Component do
     |> Enum.reject(&is_nil/1)
   end
 
+  defp append_selection(_value, _current_selection, :single, _value_mapper) do
+    raise """
+    Appending values only works in `:tags` mode
+    """
+  end
+
+  defp append_selection(nil, current_selection, _mode, _value_mapper), do: current_selection
+
+  defp append_selection(value, current_selection, :tags, value_mapper) do
+    value = if Enumerable.impl_for(value), do: value, else: [value]
+
+    normalized_value = Enum.map(value, &normalize_selection_value(&1, current_selection, value_mapper))
+
+    current_selection ++ normalized_value
+    |> Enum.reject(&is_nil/1)
+    |> Enum.uniq()
+  end
+
   defp normalize_selection_value(%Ecto.Changeset{action: :replace}, _options, _value_mapper),
     do: nil
 

test/live_select_tags_test.exs

@@ -379,6 +379,58 @@ defmodule LiveSelectTagsTest do
     assert_selected_multiple(live, [%{label: "C", value: 3}, %{label: "E", value: 5}])
   end
 
+  test "can append values to the selection", %{conn: conn} do
+    {:ok, live, _html} = live(conn, "/?mode=tags")
+
+    stub_options(~w(A B C))
+
+    type(live, "ABC")
+
+    select_nth_option(live, 1)
+
+    assert_selected_multiple(live, ~w(A))
+
+    send_update(live, append: ["B"])
+
+    assert_selected_multiple(live, ~w(A B))
+
+    send_update(live, append: "C")
+
+    assert_selected_multiple(live, ~w(A B C))
+  end
+
+  test "does not duplicate selection when appending values", %{conn: conn} do
+    {:ok, live, _html} = live(conn, "/?mode=tags")
+
+    stub_options(~w(A B C))
+
+    type(live, "ABC")
+
+    select_nth_option(live, 1)
+
+    assert_selected_multiple(live, ~w(A))
+
+    send_update(live, append: ~w(A))
+
+    assert_selected_multiple(live, ~w(A))
+  end
+
+  test "does not change the selection when appending nil values", %{conn: conn} do
+    {:ok, live, _html} = live(conn, "/?mode=tags")
+
+    stub_options(~w(A B C))
+
+    type(live, "ABC")
+
+    select_nth_option(live, 1)
+
+    assert_selected_multiple(live, ~w(A))
+
+    send_update(live, append: nil)
+
+    assert_selected_multiple(live, ~w(A))
+  end
+
   test "can render custom clear button", %{conn: conn} do
     {:ok, live, _html} = live(conn, "/live_component_test")