init after destroy(false) doesn't work

Subject of the issue

A grid initialised on the DOM left by grid.destroy(false) doesn't seem to work: widgets are not draggable.

Your environment

• version of gridstack.js 1.1.0
• which browser and its version Chrome Version 80.0.3987.132 (Official Build) (64-bit)

Steps to reproduce

grid = GridStack.init() // works well
grid.destroy(false)
grid = GridStack.init() // widgets are no longer draggable

https://jsfiddle.net/n4f2dpv5/

Expected behaviour

Initialising a new grid (GridStack.init()) on the DOM of the destroyed one (grid.destroy(false)) should work the same way as initialising a "fresh" grid.

[adumesny]

Hey thanks,
did this ever worked before ?
I assume this is a valid user case - what are you trying to do ?
FYI you can disable grid drag/resize by making the grid fixed as well instead of 'destroying it' and re-creating, in case you didn't know.

@adumesny Hi!

did this ever worked before ?

I haven't tried it before.

I assume this is a valid user case - what are you trying to do ?

I'm trying to use gridstack.js with phoenix liveview through so called hooks. The only way I have found for it to work so far is to destroy gridstack before update, and then reinit it after liveview patches the widgets in the DOM:

// WidgetGridHook.js

function positions(items) {
  return items.reduce((acc, item) => {
    let widgetId = item.el.id;
    acc[widgetId] = {
      x: item.x,
      y: item.y,
      width: item.width,
      height: item.height
    };
    return acc;
  }, {});
}

const WidgetGridHook = {
  mounted() {
    this.grid = GridStack.init();

    this.grid.on("change", (_event, items) => {
      if (items) {
        this.pushEvent("widget:move", { positions: positions(items) });
      }
    });
  },

  beforeUpdate() {
    this.grid.destroy(false);
  },

  updated() {
    this.grid = GridStack.init();

    this.grid.on("change", (_event, items) => {
      if (items) {
        this.pushEvent("widget:move", { positions: positions(items) });
      }
    });
  },

  beforeDestroy() {
    this.grid.destroy(false);
  }
};

export default WidgetGridHook;

And the liveview:

defmodule PlaybookWeb.PlaybookLive do
  use Phoenix.LiveView
  alias App.{Dashboards, Accounts}
  alias Dashboards.Dashboard

  def render(assigns) do
    positions = Dashboard.widget_positions(assigns.dashboard)

    ~L"""
    <div
      class="grid-stack"
      phx-hook="WidgetGridHook"
      style="height: 540px;">
      <%= for widget <- @dashboard.widgets do %>
        <div
          id="<%= widget.id %>"
          class="grid-stack-item"
          data-gs-x="<%= positions[widget.id]["x"] %>"
          data-gs-y="<%= positions[widget.id]["y"] %>"
          data-gs-width="<%= positions[widget.id]["width"] %>"
          data-gs-height="<%= positions[widget.id]["height"] %>"
          data-gs-min-width="1"
          data-gs-min-height="2">
          <div class="grid-stack-item-content bg-white h-100">
            <%= WidgetView.render("widget.html", widget: widget) %>
          </div>
        </div>
      <% end %>
    </div>
    """
  end

  def mount(%{"dashboard_id" => dashboard_id}, %{"user_id" => user_id}, socket) do
    if connected?(socket) do
      :ok = Dashboards.subscribe(dashboard_id)
    end

    current_user = Accounts.get_user!(user_id)
    dashboard = Dashboards.get_dashboard!(dashboard_id, current_user)
    {:ok, assign(socket, current_user: current_user, dashboard: dashboard)}
  end

  def handle_event("widget:move", %{"positions" => new_positions}, socket) do
    %{dashboard: dashboard, current_user: current_user} = socket.assigns
    old_positions = Dashboard.widget_positions(dashboard)

    positions =
      Enum.reduce(new_positions, old_positions, fn {widget_id, new_position}, acc ->
        Map.put(acc, widget_id, new_position)
      end)

    {:ok, dashboard} = Dashboards.persist_positions(dashboard, positions, current_user)
    {:noreply, assign(socket, dashboard: dashboard)}
  end
end

---

So the way it works right now is

1. A browser makes a request for dashboards and gets the rendered HTML from PlaybookWeb.PlaybookLive.render/1 above.
2. After that the browser makes a websocket connection to the server and initialises the liveview on the client together with WidgetGridHook which creates the grid in mounted().
3. Now when the widget is moved, the browser sends "widget:move" event to the server which makes it persist the new positions and send the patched HTML back to the client.
4. This is the step which is problematic. Phoenix LiveView uses morphdom to patch the DOM, which at least in my setup, results in the grid breaking down on any patch to .grid-stack children arriving from the server (the widgets disappear from the screen), so my attempt to make it work was to destroy the gridstack instance right before the update (beforeUpdate hook) and then reinitialise it with the new, updated DOM.

[adumesny]

simple possible workaround for now (there might be more issues as I discovered stuff we didn't do during destroy(false) is to call grid.enable(); after you init the second time.

still a bug that it doesn't work out of the box.

[adumesny]

fixed in next release.

@adumesny thank you!