Full DataSource=resource support in GridView and DataPager

src/Framework/Core/Controls/GenericGridViewDataSet.cs

@@ -29,7 +29,7 @@ public class GenericGridViewDataSet<
         /// <summary>
         /// Gets or sets the items for the current page.
         /// </summary>
-        public IList<T> Items { get; set; } = new List<T>();
+        public virtual IList<T> Items { get; set; } = new List<T>();
 
         /// <summary>
         /// Gets or sets whether the data should be refreshed. This property is set to true automatically

src/Framework/Core/Controls/ServerSideGridViewDataSet.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using DotVVM.Framework.ViewModel;
+
+namespace DotVVM.Framework.Controls
+{
+    /// <summary>
+    /// Represents a collection of items with paging and sorting which keeps the Items collection server-side (Bind(Direction.None)) and only transfers the necessary metadata (page index, sort direction). 
+    /// </summary>
+    /// <typeparam name="T">The type of the elements in the collection.</typeparam>
+    public class ServerSideGridViewDataSet<T>()
+        : GenericGridViewDataSet<T, NoFilteringOptions, SortingOptions, PagingOptions, NoRowInsertOptions, NoRowEditOptions>(new(), new(), new(), new(), new())
+    {
+
+        [Bind(Direction.None)]
+        public override IList<T> Items { get => base.Items; set => base.Items = value; }
+        // return specialized dataset options
+        public new GridViewDataSetOptions GetOptions()
+        {
+            return new GridViewDataSetOptions {
+                FilteringOptions = FilteringOptions,
+                SortingOptions = SortingOptions,
+                PagingOptions = PagingOptions
+            };
+        }
+    }
+}

src/Framework/Framework/Binding/BindingPropertyException.cs

@@ -38,7 +38,7 @@ static string GetMessage(IBinding binding, Type[] properties, string? message, E
 
             var introMsg =
                 isRequiredProperty ?
-                $"Could not initialize binding as it is missing a required property {properties[0].Name}" :
+                $"Could not initialize binding '{binding}' as it is missing a required property {properties[0].Name}" :
                 $"Unable to get property {properties[0].Name}";
 
             var pathMsg = "";

src/Framework/Framework/Binding/DotvvmBindingCacheHelper.cs

@@ -56,7 +56,8 @@ public ValueBindingExpression<TResult> CreateValueBinding<TResult>(string code,
                 new ValueBindingExpression<TResult>(compilationService, new object?[] {
                     dataContext,
                     new OriginalStringBindingProperty(code),
-                    parserOptions
+                    parserOptions,
+                    new ExpectedTypeBindingProperty(typeof(TResult))
                 }));
         }
 
@@ -78,7 +79,8 @@ public ResourceBindingExpression<TResult> CreateResourceBinding<TResult>(string
                 new ResourceBindingExpression<TResult>(compilationService, new object?[] {
                     dataContext,
                     new OriginalStringBindingProperty(code),
-                    parserOptions
+                    parserOptions,
+                    new ExpectedTypeBindingProperty(typeof(TResult))
                 }));
         }
 
@@ -100,7 +102,8 @@ public CommandBindingExpression<TResult> CreateCommand<TResult>(string code, Dat
                 new CommandBindingExpression<TResult>(compilationService, new object?[] {
                     dataContext,
                     new OriginalStringBindingProperty(code),
-                    parserOptions
+                    parserOptions,
+                    new ExpectedTypeBindingProperty(typeof(TResult))
                 }));
         }
 
@@ -122,7 +125,8 @@ public StaticCommandBindingExpression<TResult> CreateStaticCommand<TResult>(stri
                 new StaticCommandBindingExpression<TResult>(compilationService, new object?[] {
                     dataContext,
                     new OriginalStringBindingProperty(code),
-                    parserOptions
+                    parserOptions,
+                    new ExpectedTypeBindingProperty(typeof(TResult))
                 }));
         }
 

src/Framework/Framework/Compilation/Binding/GeneralBindingPropertyResolvers.cs

@@ -430,7 +430,6 @@ public CollectionElementDataContextBindingProperty GetCollectionElementDataConte
             return new CollectionElementDataContextBindingProperty(DataContextStack.CreateCollectionElement(
                 ReflectionUtils.GetEnumerableType(resultType.Type).NotNull(),
                 parent: dataContext,
-                extensionParameters: new CollectionElementDataContextChangeAttribute(order: 0).GetExtensionParameters(new ResolvedTypeDescriptor(dataContext.DataContextType)).ToArray(),
                 serverSideOnly: binding is not IValueBinding
             ));
         }

src/Framework/Framework/Compilation/ControlTree/DataContextStack.cs

@@ -44,6 +44,16 @@ private DataContextStack(Type type,
             BindingPropertyResolvers = bindingPropertyResolvers?.ToImmutableArray() ?? ImmutableArray<Delegate>.Empty;
             ServerSideOnly = serverSideOnly;
 
+            if (ExtensionParameters.Length >= 2)
+            {
+                var set = new HashSet<string>(StringComparer.Ordinal);
+                foreach (var p in ExtensionParameters)
+                {
+                    if (!set.Add(p.Identifier))
+                        throw new Exception($"Extension parameter '{p.Identifier}' is defined multiple times in the data context stack {this}");
+                }
+            }
+
             hashCode = ComputeHashCode();
         }
 

src/Framework/Framework/Controls/CheckBox.cs

@@ -30,7 +30,7 @@ public bool? Checked
         }
 
         public static readonly DotvvmProperty CheckedProperty =
-            DotvvmProperty.Register<bool?, CheckBox>(t => t.Checked, false);
+            DotvvmProperty.Register<bool?, CheckBox>(t => t.Checked, null);
 
         /// <summary>
         /// Gets or sets a collection of values of all checked checkboxes. Use this property in combination with the CheckedValue property.
@@ -60,12 +60,14 @@ public bool DisableIndeterminate
         /// </summary>
         protected override void RenderInputTag(IHtmlWriter writer)
         {
-            if (HasValueBinding(CheckedProperty) && !HasValueBinding(CheckedItemsProperty))
+            var checkedValue = GetValueRaw(CheckedProperty);
+            var checkedItemsValue = GetValueRaw(CheckedItemsProperty);
+            if (checkedValue is {} && checkedItemsValue is null)
             {
                 // boolean mode
-                RenderCheckedProperty(writer);
+                RenderCheckedProperty(writer, checkedValue);
             }
-            else if (!HasValueBinding(CheckedProperty) && HasValueBinding(CheckedItemsProperty))
+            else if (checkedValue is null && checkedItemsValue is {})
             {
                 // collection mode
                 RenderCheckedItemsProperty(writer);
@@ -121,18 +123,26 @@ protected virtual void RenderCheckedItemsBinding(IHtmlWriter writer)
             writer.AddKnockoutDataBind("dotvvm-checkedItems", checkedItemsBinding!.GetKnockoutBindingExpression(this));
         }
 
-        protected virtual void RenderCheckedProperty(IHtmlWriter writer)
+        protected virtual void RenderCheckedProperty(IHtmlWriter writer, object? checkedValue)
         {
-            var checkedBinding = GetValueBinding(CheckedProperty);
-
-            // dotvvm-CheckState sets elements to indeterminate state when checkedBinding is null,
-            // knockout's default checked binding does not do that
-            var bindingHandler = DisableIndeterminate ? "checked" : "dotvvm-CheckState";
-            writer.AddKnockoutDataBind(bindingHandler, checkedBinding!, this);
-
-            // Boolean mode can have prerendered `checked` attribute
-            if (RenderOnServer && true.Equals(GetValue(CheckedProperty)))
-                writer.AddAttribute("checked", null);
+            if (checkedValue is IValueBinding checkedBinding)
+            {
+                // dotvvm-CheckState sets elements to indeterminate state when checkedBinding is null,
+                // knockout's default checked binding does not do that
+                var bindingHandler = DisableIndeterminate ? "checked" : "dotvvm-CheckState";
+                writer.AddKnockoutDataBind(bindingHandler, checkedBinding!, this);
+
+                // Boolean mode can have prerendered `checked` attribute
+                if (RenderOnServer && KnockoutHelper.TryEvaluateValueBinding(this, checkedBinding) is true)
+                    writer.AddAttribute("checked", null);
+            }
+            else
+            {
+                if ((bool?)EvalPropertyValue(CheckedProperty, checkedValue) is true)
+                {
+                    writer.AddAttribute("checked", null);
+                }
+            }
         }
 
 

src/Framework/Framework/Controls/DataPager.cs

@@ -163,7 +163,7 @@ protected virtual void DataBind(Hosting.IDotvvmRequestContext context)
         {
             Children.Clear();
 
-            var dataSetBinding = GetValueBinding(DataSetProperty)!;
+            var dataSetBinding = GetDataSetBinding();
             var dataSetType = dataSetBinding.ResultType;
 
             var commandType = LoadData is {} ? GridViewDataSetCommandType.LoadDataDelegate : GridViewDataSetCommandType.Default;
@@ -318,8 +318,9 @@ protected override void AddAttributesToRender(IHtmlWriter writer, IDotvvmRequest
 
             if (this.LoadData is {} loadData)
             {
+                var dataSetBinding = GetDataSetBinding() as IValueBinding ?? throw new DotvvmControlException(this, "The DataSet property must set to a value binding when LoadData command is used!");
                 var helperBinding = new KnockoutBindingGroup();
-                helperBinding.Add("dataSet", GetDataSetBinding().GetKnockoutBindingExpression(this, unwrapped: true));
+                helperBinding.Add("dataSet", dataSetBinding.GetKnockoutBindingExpression(this, unwrapped: true));
                 var loadDataExpression = KnockoutHelper.GenerateClientPostbackLambda("LoadData", loadData, this, new PostbackScriptOptions(elementAccessor: "$element", koContext: CodeParameterAssignment.FromIdentifier("$context")));
                 helperBinding.Add("loadDataSet", loadDataExpression);
                 writer.AddKnockoutDataBind("dotvvm-gridviewdataset", helperBinding.ToString());
@@ -356,8 +357,7 @@ protected override void RenderEndTag(IHtmlWriter writer, IDotvvmRequestContext c
         {
         }
 
-
-        private IValueBinding GetDataSetBinding()
-            => GetValueBinding(DataSetProperty) ?? throw new DotvvmControlException(this, "The DataSet property of the dot:DataPager control must be set!");
+        private IStaticValueBinding GetDataSetBinding()
+            => GetValueOrResourceBinding(DataSetProperty) ?? throw new DotvvmControlException(this, "The DataSet property of the dot:DataPager control must be set!");
     }
 }

src/Framework/Framework/Controls/DotvvmBindableObject.cs

@@ -223,6 +223,22 @@ public void SetValueRaw(DotvvmProperty property, object? value)
             return binding as IValueBinding;
         }
 
+        /// <summary>
+        /// Gets the value binding set to a specified property. Returns null if the property is not a binding, throws if the binding some kind of command.
+        /// </summary>
+        public IStaticValueBinding? GetValueOrResourceBinding(DotvvmProperty property, bool inherit = true)
+        {
+            var binding = GetBinding(property, inherit);
+            if (binding is null)
+                return null;
+            if (binding is not IStaticValueBinding valueBinding)
+            {
+                // throw exception on incompatible binding types
+                throw new BindingHelper.BindingNotSupportedException(binding) { RelatedControl = this };
+            }
+            return valueBinding;
+        }
+
         /// <summary> Returns a Javascript (knockout) expression representing value or binding of this property. </summary>
         public ParametrizedCode GetJavascriptValue(DotvvmProperty property, bool inherit = true) =>
             GetValueOrBinding<object>(property, inherit).GetParametrizedJsExpression(this);

src/Framework/Framework/Controls/GridView.cs

@@ -332,15 +332,9 @@ private static void SetCellAttributes(GridViewColumn column, HtmlGenericControl
 
             if (!isHeaderCell)
             {
-                var cssClassBinding = column.GetValueBinding(GridViewColumn.CssClassProperty);
-                if (cssClassBinding != null)
-                {
-                    cellAttributes["class"] = cssClassBinding;
-                }
-                else if (!string.IsNullOrWhiteSpace(column.CssClass))
-                {
-                    cellAttributes["class"] = column.CssClass;
-                }
+                if (column.GetValueRaw(GridViewColumn.CssClassProperty) is {} cssClassBinding &&
+                    cssClassBinding is not "")
+                    cellAttributes.Set("class", cssClassBinding);
             }
             else
             {

src/Framework/Framework/Controls/GridViewCheckBoxColumn.cs

@@ -1,4 +1,5 @@
 using DotVVM.Framework.Binding;
+using DotVVM.Framework.Binding.Expressions;
 using DotVVM.Framework.Binding.Properties;
 using DotVVM.Framework.Hosting;
 
@@ -14,13 +15,13 @@ public class GridViewCheckBoxColumn : GridViewColumn
         /// Gets or sets a binding which retrieves the value to display from the current data item.
         /// </summary>
         [MarkupOptions(AllowHardCodedValue = false, Required = true)]
-        public bool ValueBinding
+        public IStaticValueBinding<bool?> ValueBinding
         {
-            get { return (bool)GetValue(ValueBindingProperty)!; }
+            get { return (IStaticValueBinding<bool?>)GetValueRaw(ValueBindingProperty)!; }
             set { SetValue(ValueBindingProperty, value); }
         }
         public static readonly DotvvmProperty ValueBindingProperty =
-            DotvvmProperty.Register<bool, GridViewCheckBoxColumn>(c => c.ValueBinding);
+            DotvvmProperty.Register<IStaticValueBinding<bool?>, GridViewCheckBoxColumn>(c => c.ValueBinding);
 
         /// <summary> Whether to automatically attach Validator.Value onto the TextBox or add a standalone Validator component. </summary>
         public ValidatorPlacement ValidatorPlacement
@@ -51,17 +52,17 @@ private void CreateControlsCore(DotvvmControl container, bool enabled)
             var checkBox = new CheckBox { Enabled = enabled };
             CopyProperty(UITests.NameProperty, checkBox, UITests.NameProperty);
 
-            var valueBinding = GetValueBinding(ValueBindingProperty);
-            checkBox.SetBinding(CheckBox.CheckedProperty, valueBinding);
-            Validator.Place(checkBox, container.Children, valueBinding, ValidatorPlacement);
+            var binding = ValueBinding;
+            checkBox.SetBinding(CheckBox.CheckedProperty, binding);
+            Validator.Place(checkBox, container.Children, binding as IValueBinding, ValidatorPlacement);
             container.Children.Add(checkBox);
         }
 
         protected override string? GetSortExpression()
         {
             if (string.IsNullOrEmpty(SortExpression))
             {
-                return GetValueBinding(ValueBindingProperty)?.GetProperty<OriginalStringBindingProperty>()?.Code ??
+                return GetBinding(ValueBindingProperty)?.GetProperty<OriginalStringBindingProperty>()?.Code ??
                        throw new DotvvmControlException(this, $"The 'ValueBinding' property must be set on the '{GetType()}' control!");
             }
             else