Fix issue for Cmd in init

Author: TimLariviere

CHANGELOG.md

@@ -9,6 +9,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 _No unreleased changes_
 
+## [3.0.0-pre9] - 2024-11-08
+
+### Fixed
+- Fixed an issue where using Cmd in init would not refresh the view by @TimLariviere
+
 ## [3.0.0-pre8] - 2024-11-07
 
 ### Changed
@@ -157,7 +162,8 @@ _No unreleased changes_
 ### Changed
 - Fabulous.XamarinForms & Fabulous.MauiControls have been moved been out of the Fabulous repository. Find them in their own repositories: [https://github.com/fabulous-dev/Fabulous.XamarinForms](https://github.com/fabulous-dev/Fabulous.XamarinForms) / [https://github.com/fabulous-dev/Fabulous.MauiControls](https://github.com/fabulous-dev/Fabulous.MauiControls)
 
-[unreleased]: https://github.com/fabulous-dev/Fabulous/compare/3.0.0-pre8...HEAD
+[unreleased]: https://github.com/fabulous-dev/Fabulous/compare/3.0.0-pre9...HEAD
+[3.0.0-pre9]: https://github.com/fabulous-dev/Fabulous/releases/tag/3.0.0-pre9
 [3.0.0-pre8]: https://github.com/fabulous-dev/Fabulous/releases/tag/3.0.0-pre8
 [3.0.0-pre7]: https://github.com/fabulous-dev/Fabulous/releases/tag/3.0.0-pre7
 [3.0.0-pre6]: https://github.com/fabulous-dev/Fabulous/releases/tag/3.0.0-pre6

src/Fabulous/Components/Component.fs

@@ -22,6 +22,9 @@ type Component
     let mutable _view = null
     let mutable _contextSubscription: IDisposable = null
 
+    let mutable _isReadyForRenderRequest = false
+    let mutable _pendingRenderRequested = false
+
     member private this.MergeAttributes(rootWidget: Widget, componentWidgetOpt: Widget voption) =
         match componentWidgetOpt with
         | ValueNone -> struct (rootWidget.ScalarAttributes, rootWidget.WidgetAttributes, rootWidget.WidgetCollectionAttributes)
@@ -60,6 +63,9 @@ type Component
             struct (scalars, widgets, widgetColls)
 
     member this.CreateView(componentWidget: Widget voption) =
+        _isReadyForRenderRequest <- false
+        _contextSubscription <- _context.RenderNeeded.Subscribe(this.Render)
+
         let struct (envContext, treeContext, context, rootWidget) =
             _body.Invoke(_envContext, _treeContext, _context)
 
@@ -87,11 +93,20 @@ type Component
             widgetDef.CreateView(rootWidget, envContext, treeContext, ValueNone)
 
         _view <- view
-        _contextSubscription <- _context.RenderNeeded.Subscribe(this.Render)
+        _isReadyForRenderRequest <- true
+
+        // ComponentContext.SetNeedsRender has been called before the view is created
+        // We need to re-render the component now because the state has changed before we were ready
+        if _pendingRenderRequested then
+            _pendingRenderRequested <- false
+            this.Render()
 
         struct (node, view)
 
     member this.AttachView(componentWidget: Widget, view: obj) =
+        _isReadyForRenderRequest <- false
+        _contextSubscription <- _context.RenderNeeded.Subscribe(this.Render)
+
         let struct (envContext, treeContext, context, rootWidget) =
             _body.Invoke(_envContext, _treeContext, _context)
 
@@ -119,7 +134,13 @@ type Component
             widgetDef.AttachView(rootWidget, envContext, treeContext, ValueNone, view)
 
         _view <- view
-        _contextSubscription <- _context.RenderNeeded.Subscribe(this.Render)
+        _isReadyForRenderRequest <- true
+
+        // ComponentContext.SetNeedsRender has been called before the view is created
+        // We need to re-render the component now because the state has changed before we were ready
+        if _pendingRenderRequested then
+            _pendingRenderRequested <- false
+            this.Render()
 
         node
 
@@ -139,6 +160,7 @@ type Component
 
             if prevContext <> context then
                 _contextSubscription.Dispose()
+                prevContext.Dispose()
                 _contextSubscription <- context.RenderNeeded.Subscribe(this.Render)
                 _context <- context
 
@@ -164,8 +186,10 @@ type Component
     interface IDisposable with
         member this.Dispose() = this.Dispose()
 
-    member this.Render _ =
+    member this.Render() =
         if isNull _body then
             () // Component has been disposed
+        else if not _isReadyForRenderRequest then
+            _pendingRenderRequested <- true
         else
             treeContext.SyncAction(this.RenderInternal)

src/Fabulous/Components/ComponentContext.fs

@@ -68,9 +68,9 @@ type ComponentContext(initialSize: int) =
         this.SetValueInternal(key, value)
         this.NeedsRender()
 
-    member this.LinkDisposable(key: string, disposable: unit -> IDisposable) =
+    member this.LinkDisposable<'T when 'T :> IDisposable>(key: string, disposable: unit -> 'T) =
         if disposables.ContainsKey(key) then
-            disposables[key]
+            disposables[key] :?> 'T
         else
             let disposable = disposable()
             disposables[key] <- disposable

src/Fabulous/Components/Mvu.fs

@@ -30,35 +30,26 @@ type MvuExtensions =
                 | ValueNone ->
                     let struct (program, arg) = fn.Invoke()
 
-                    let programObj: Program<obj, obj, obj> =
-                        { Init = fun arg -> let model, cmd = program.Init(unbox arg) in (box model, Cmd.map box cmd)
-                          Update = fun (msg, model) -> let model, cmd = program.Update(unbox msg, unbox model) in (box model, Cmd.map box cmd)
-                          Subscribe = fun model -> Sub.map "mvu" box (program.Subscribe(unbox model))
-                          Logger = program.Logger
-                          ExceptionHandler = program.ExceptionHandler }
-
                     let runner =
                         context.LinkDisposable(
                             "runner",
                             fun () ->
                                 let getModel () =
                                     match context.TryGetValue<ModelValue<'model>>(key) with
                                     | ValueNone -> failwith("Model not found in ComponentContext " + context.Id.ToString())
-                                    | ValueSome(ModelValue model) -> box model
+                                    | ValueSome(ModelValue model) -> model
 
-                                let setModel v =
-                                    context.SetValue(key, ModelValue(unbox<'model> v))
-                                    context.NeedsRender()
+                                let setModel v = context.SetValue(key, ModelValue v)
 
-                                let runner = new Runner<obj, obj, obj>(getModel, setModel, programObj)
-                                runner.Start(arg)
-                                runner
+                                new Runner<'arg, 'model, 'msg>(getModel, setModel, program)
                         )
 
                     // Redirect messages to runner
                     let treeContext =
                         { treeContext with
-                            Dispatch = (runner :?> Runner<obj, obj, obj>).Dispatch }
+                            Dispatch = unbox >> runner.Dispatch }
+
+                    runner.Start(arg)
 
                     let (ModelValue state) = context.TryGetValue(key).Value
 

src/Fabulous/Runner.fs

@@ -27,6 +27,8 @@ type Runner<'arg, 'model, 'msg>(getState: unit -> 'model, setState: 'model -> un
             let newModel, cmd = program.Update(lastMsg.Value, model)
             let subs = program.Subscribe(newModel)
 
+            printfn $"Updating model. Was %A{model}, Is %A{newModel}"
+
             setState newModel
 
             _activeSubs <- Sub.Internal.diff _activeSubs subs |> Sub.Internal.Fx.change onError dispatch