# `GanttEx.Event`
[🔗](https://github.com/rocket4ce/gantt_ex/blob/v0.1.0/lib/gantt_ex/event.ex#L1)

Notifications sent by `GanttEx.Live.Gantt` to the LiveView that renders it.

Every change made by the user (dragging a bar, editing a task in the
lightbox, drawing a dependency, ...) is applied to the chart immediately and
reported to the parent LiveView process as a message:

    {GanttEx, %GanttEx.Event{}}

so the parent can persist it:

    def handle_info({GanttEx, %GanttEx.Event{type: :task_updated, task: task}}, socket) do
      Planning.update_task!(task.id, GanttEx.Task.to_map(task))
      {:noreply, socket}
    end

    def handle_info({GanttEx, %GanttEx.Event{}}, socket), do: {:noreply, socket}

## Types

  * `:task_created` - `:task` holds the new task. Its id is temporary (a
    string starting with `"gx-"`) unless it came from your own data;
    re-render the component with the persisted tasks to replace it.
  * `:task_updated` - `:task` holds the updated task and `:changes` the
    changed fields with their new values. Also sent for parent projects whose
    dates were recomputed.
  * `:task_deleted` - one event per deleted task (descendants first).
  * `:task_moved` - the task changed position in the tree: `:parent`, `:index`
    and `:siblings` (ordered ids of the new siblings) describe where.
  * `:link_created`, `:link_updated`, `:link_deleted` - `:link` holds the link,
    `:changes` the changed fields for updates.
  * `:branch_requested` - the user expanded a task with `has_children: true`
    whose children are not loaded yet: load them and render the component
    with them (dynamic loading).
  * `:task_selected` - the user selected a task (`:task`). `:selection` holds
    the ids of every selected task (Ctrl/Cmd+click and Shift+click select
    several).

`:gantt_id` is the `id` of the component that sent the event, which allows
several charts in the same LiveView.

# `t`

```elixir
@type t() :: %GanttEx.Event{
  changes: map() | nil,
  gantt_id: String.t(),
  index: non_neg_integer() | nil,
  link: GanttEx.Link.t() | nil,
  parent: GanttEx.Task.id() | nil,
  selection: [GanttEx.Task.id()] | nil,
  siblings: [GanttEx.Task.id()] | nil,
  task: GanttEx.Task.t() | nil,
  type: type()
}
```

# `type`

```elixir
@type type() ::
  :task_created
  | :task_updated
  | :task_deleted
  | :task_moved
  | :link_created
  | :link_updated
  | :link_deleted
  | :task_selected
  | :branch_requested
```

# `from_change`

```elixir
@spec from_change(String.t(), GanttEx.Store.change()) :: t()
```

Builds an event from a `t:GanttEx.Store.change/0`.

    iex> task = GanttEx.Task.new!(id: 1, start_date: ~D[2025-01-01])
    iex> event = GanttEx.Event.from_change("gantt", {:task_updated, task, %{changes: %{text: "A"}}})
    iex> {event.gantt_id, event.type, event.task.id, event.changes}
    {"gantt", :task_updated, 1, %{text: "A"}}

    iex> link = GanttEx.Link.new!(id: 9, source: 1, target: 2)
    iex> GanttEx.Event.from_change("gantt", {:link_deleted, link, %{}}).link.id
    9

# `notify`

```elixir
@spec notify(pid(), t()) :: t()
```

Sends the event to `pid` as `{GanttEx, event}`.

---

*Consult [api-reference.md](api-reference.md) for complete listing*