Managing bindings in bindable RecyclerView adapter and view holders (#…

…561) * Added possibility to attach/detach bindings in existing BindableViewHolders * Renamed OnDestroy -> CleanUp * Fixed NullReference * Fixed attaching bindings multiple times in BindableViewHolder inheritors --------- Co-authored-by: Pavel Leonenko <[email protected]>
Softeq · Sep 27, 2024 · 73280be · 73280be
1 parent 3aae257
commit 73280be
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Showing 4 changed files with 64 additions and 20 deletions.
diff --git a/Softeq.XToolkit.Bindings.Droid/Bindable/BindableRecyclerViewAdapter.cs b/Softeq.XToolkit.Bindings.Droid/Bindable/BindableRecyclerViewAdapter.cs
@@ -13,21 +13,23 @@
 using Softeq.XToolkit.Common.Collections;
 using Softeq.XToolkit.Common.Collections.EventArgs;
 using Softeq.XToolkit.Common.Commands;
+using Softeq.XToolkit.Common.Extensions;
 using Softeq.XToolkit.Common.Weak;
 
 #nullable disable
 
 namespace Softeq.XToolkit.Bindings.Droid.Bindable
 {
-    public abstract class BindableRecyclerViewAdapterBase<TItem, TItemHolder> : RecyclerView.Adapter
+    public abstract class BindableRecyclerViewAdapterBase<TItem, TItemHolder> : RecyclerView.Adapter, IBindableRecyclerViewAdapter
         where TItemHolder : BindableViewHolder<TItem>
     {
         protected readonly IList<FlatItem> _flatMapping = new List<FlatItem>();
+        private readonly List<IBindableViewHolder> _existingBindableViewHolders = new();
 
         protected IDisposable _subscription;
-        private protected ICommand<TItem> _itemClick;
+        private ICommand<TItem> _itemClick;
 
-        public BindableRecyclerViewAdapterBase(
+        protected BindableRecyclerViewAdapterBase(
             Type headerViewHolder,
             Type footerViewHolder)
         {
@@ -93,24 +95,51 @@ public override void OnViewDetachedFromWindow(Java.Lang.Object holder)
             base.OnViewDetachedFromWindow(holder);
         }
 
-        public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
+        public sealed override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
         {
-            var itemType = (ItemType) viewType;
+            var result = DoCreateViewHolder(parent, viewType);
 
-            switch (itemType)
+            if (result is IBindableViewHolder bindableViewHolder)
             {
-                case ItemType.Header:
-                    return OnCreateHeaderViewHolder(parent);
+                _existingBindableViewHolders.Add(bindableViewHolder);
+            }
 
-                case ItemType.Item:
-                    return OnCreateItemViewHolder(parent, itemType);
+            return result;
+        }
 
-                case ItemType.Footer:
-                    return OnCreateFooterViewHolder(parent);
+        public void DoAttachBindings()
+        {
+            // ReSharper disable once ConditionIsAlwaysTrueOrFalse
+            _existingBindableViewHolders
+                .Where(x => !x.AreBindingsAttached && x.DataContext != null)
+                .Apply(x => x.DoAttachBindings());
+        }
 
-                default:
-                    throw new ArgumentException($"Unable to create a view holder for \"{viewType}\" view type.", nameof(viewType));
-            }
+        public void DoDetachBindings()
+        {
+            _existingBindableViewHolders.ForEach(x => x.DoDetachBindings());
+        }
+
+        public void CleanUp()
+        {
+            _subscription?.Dispose();
+            DoDetachBindings();
+            _existingBindableViewHolders.Clear();
+        }
+
+        protected virtual RecyclerView.ViewHolder DoCreateViewHolder(ViewGroup parent, int viewType)
+        {
+            var itemType = (ItemType) viewType;
+
+            return itemType switch
+            {
+                ItemType.Header => OnCreateHeaderViewHolder(parent),
+                ItemType.Item => OnCreateItemViewHolder(parent, itemType),
+                ItemType.Footer => OnCreateFooterViewHolder(parent),
+                _ => throw new ArgumentException(
+                    $"Unable to create a view holder for \"{viewType}\" view type.",
+                    nameof(viewType))
+            };
         }
 
         public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
@@ -139,8 +168,6 @@ public override void OnViewRecycled(Java.Lang.Object holder)
             base.OnViewRecycled(holder);
         }
 
-        public void StopListeningToSourceUpdates() => _subscription?.Dispose();
-
         protected virtual RecyclerView.ViewHolder OnCreateHeaderViewHolder(ViewGroup parent)
         {
             return CreateViewHolder(parent, HeaderViewHolder);
@@ -351,7 +378,7 @@ public BindableRecyclerViewAdapter(
 
         public override int ItemCount => _flatMapping.Count;
 
-        public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
+        protected override RecyclerView.ViewHolder DoCreateViewHolder(ViewGroup parent, int viewType)
         {
             var itemType = (ItemType) viewType;
 
@@ -363,7 +390,7 @@ public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int
                     return OnCreateSectionFooterViewHolder(parent, ItemType.SectionFooter);
 
                 default:
-                    return base.OnCreateViewHolder(parent, viewType);
+                    return base.DoCreateViewHolder(parent, viewType);
             }
         }
 
@@ -396,7 +423,7 @@ protected virtual RecyclerView.ViewHolder OnCreateSectionFooterViewHolder(ViewGr
         protected override void Dispose(bool disposing)
         {
             base.Dispose(disposing);
-            StopListeningToSourceUpdates();
+            CleanUp();
         }
 
         protected void ReloadMapping()

diff --git a/Softeq.XToolkit.Bindings.Droid/Bindable/BindableViewHolder.cs b/Softeq.XToolkit.Bindings.Droid/Bindable/BindableViewHolder.cs
@@ -32,6 +32,8 @@ protected BindableViewHolder(View itemView) : base(itemView)
 
         public object DataContext { get; private set; }
 
+        public bool AreBindingsAttached { get; private set; }
+
         protected TViewModel ViewModel => (TViewModel) DataContext;
 
         void IBindable.SetDataContext(object dataContext)
@@ -67,6 +69,7 @@ protected virtual void OnItemViewClick(object sender, EventArgs e)
 
         public virtual void DoAttachBindings()
         {
+            AreBindingsAttached = true;
             _subscriptionsComponent.CreateSubscriptions();
         }
 
@@ -75,6 +78,7 @@ public virtual void DoDetachBindings()
             this.DetachBindings();
 
             _subscriptionsComponent.DisposeSubscriptions();
+            AreBindingsAttached = false;
         }
 
         protected virtual IEnumerable<IDisposable> SetCommandsWithDisposing()

diff --git a/Softeq.XToolkit.Bindings.Droid/Bindable/IBindableRecyclerViewAdapter.cs b/Softeq.XToolkit.Bindings.Droid/Bindable/IBindableRecyclerViewAdapter.cs
@@ -0,0 +1,11 @@
+// Developed for PAWS-HALO by Softeq Development Corporation
+// http://www.softeq.com
+
+namespace Softeq.XToolkit.Bindings.Droid.Bindable;
+
+public interface IBindableRecyclerViewAdapter
+{
+    void DoAttachBindings();
+    void DoDetachBindings();
+    void CleanUp();
+}
diff --git a/Softeq.XToolkit.Bindings.Droid/Bindable/IBindableViewHolder.cs b/Softeq.XToolkit.Bindings.Droid/Bindable/IBindableViewHolder.cs
@@ -10,6 +10,8 @@ public interface IBindableViewHolder : IBindableView
     {
         event EventHandler ItemClicked;
 
+        bool AreBindingsAttached { get; }
+
         void OnAttachedToWindow();
         void OnDetachedFromWindow();
         void OnViewRecycled();