Basic support for DataContext={resource: ...}

src/AutoUI/Core/PropertyHandlers/FormEditors/EnumComboBoxFormEditorProvider.cs

@@ -42,7 +42,7 @@ public override DotvvmControl CreateControl(PropertyDisplayMetadata property, Au
                 .SetCapability(props.Html)
                 .SetProperty(c => c.Enabled, props.Enabled)
                 .SetProperty(c => c.SelectionChanged, props.Changed)
-                .SetProperty(c => c.SelectedValue, (IValueBinding)context.CreateValueBinding(property));
+                .SetProperty(c => c.SelectedValue, props.Property);
 
             if (isNullable)
             {

src/AutoUI/Core/PropertyHandlers/GridColumns/CheckBoxGridColumnProvider.cs

@@ -15,7 +15,7 @@ public override bool CanHandleProperty(PropertyDisplayMetadata property, AutoUIC
         protected override GridViewColumn CreateColumnCore(PropertyDisplayMetadata property, AutoGridViewColumn.Props props, AutoUIContext context)
         {
             var column = new GridViewCheckBoxColumn();
-            column.SetBinding(GridViewCheckBoxColumn.ValueBindingProperty, context.CreateValueBinding(property));
+            column.SetBinding(GridViewCheckBoxColumn.ValueBindingProperty, props.Property);
             return column;
         }
     }

src/DynamicData/DynamicData/DataContextStackHelper.cs

@@ -40,4 +40,4 @@ public static DataContextStack CreateChildStack(this DataContextStack dataContex
                 dataContextStack.BindingPropertyResolvers);
         }
     }
-}
+}

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/BindingHelper.cs

@@ -90,10 +90,29 @@ internal static (int stepsUp, DotvvmBindableObject target) FindDataContextTarget
             var changes = 0;
             foreach (var a in control.GetAllAncestors(includingThis: true))
             {
-                if (bindingContext.Equals(a.GetDataContextType(inherit: false)))
+                var ancestorContext = a.GetDataContextType(inherit: false);
+                if (bindingContext.Equals(ancestorContext))
                     return (changes, a);
 
-                if (a.properties.Contains(DotvvmBindableObject.DataContextProperty)) changes++;
+                // count only client-side data contexts (DataContext={resource:} is skipped in JS)
+                if (a.properties.TryGet(DotvvmBindableObject.DataContextProperty, out var ancestorRuntimeContext))
+                {
+                    if (a.properties.TryGet(Internal.IsServerOnlyDataContextProperty, out var isServerOnly) && isServerOnly != null)
+                    {
+                        if (isServerOnly is false)
+                            changes++;
+                    }
+                    else
+                    {
+                        // we only count bindings which are not value bindings as client-side
+                        // scalar values (null or otherwise) are used by Repeater to the collection elements
+                        // (since this logic got inlined into many other ItemsControls and is painful to debug, let's not change it)
+                        if (ancestorRuntimeContext is null ||
+                            ancestorRuntimeContext is IValueBinding ||
+                            ancestorRuntimeContext is not IBinding)
+                            changes++;
+                    }
+                }
             }
 
             // try to get the real objects, to see which is wrong
@@ -361,10 +380,12 @@ public static Func<TParam, TResult> Cache<TParam, TResult>(this Func<TParam, TRe
             return f => cache.GetOrAdd(f, func);
         }
 
-        public static IValueBinding GetThisBinding(this DotvvmBindableObject obj)
+        public static IStaticValueBinding GetThisBinding(this DotvvmBindableObject obj)
         {
-            var dataContext = obj.GetValueBinding(DotvvmBindableObject.DataContextProperty);
-            return (IValueBinding)dataContext!.GetProperty<ThisBindingProperty>().binding;
+            var dataContext = (IStaticValueBinding?)obj.GetBinding(DotvvmBindableObject.DataContextProperty);
+            if (dataContext is null)
+                throw new InvalidOperationException("DataContext must be set to a binding to allow creation of a {value: _this} binding");
+            return (IStaticValueBinding)dataContext!.GetProperty<ThisBindingProperty>().binding;
         }
 
         private static readonly ConditionalWeakTable<Expression, BindingParameterAnnotation> _expressionAnnotations =
@@ -403,7 +424,7 @@ public static TControl SetDataContextTypeFromDataSource<TControl>(this TControl
                 return dataContextType;
             }
 
-            var (childType, extensionParameters, addLayer) = ApplyDataContextChange(dataContextType, property.DataContextChangeAttributes, obj, property);
+            var (childType, extensionParameters, addLayer, serverOnly) = ApplyDataContextChange(dataContextType, property.DataContextChangeAttributes, obj, property);
 
             if (!addLayer)
             {
@@ -412,7 +433,7 @@ public static TControl SetDataContextTypeFromDataSource<TControl>(this TControl
             }
 
             if (childType is null) return null; // childType is null in case there is some error in processing (e.g. enumerable was expected).
-            else return DataContextStack.Create(childType, dataContextType, extensionParameters: extensionParameters.ToArray());
+            else return DataContextStack.Create(childType, dataContextType, extensionParameters: extensionParameters.ToArray(), serverSideOnly: serverOnly);
         }
 
         /// <summary> Return the expected data context type for this property. Returns null if the type is unknown. </summary>
@@ -432,7 +453,7 @@ public static DataContextStack GetDataContextType(this DotvvmProperty property,
                 return dataContextType;
             }
 
-            var (childType, extensionParameters, addLayer) = ApplyDataContextChange(dataContextType, property.DataContextChangeAttributes, obj, property);
+            var (childType, extensionParameters, addLayer, serverOnly) = ApplyDataContextChange(dataContextType, property.DataContextChangeAttributes, obj, property);
 
             if (!addLayer)
             {
@@ -443,14 +464,16 @@ public static DataContextStack GetDataContextType(this DotvvmProperty property,
             if (childType is null)
                 childType = typeof(UnknownTypeSentinel);
 
-            return DataContextStack.Create(childType, dataContextType, extensionParameters: extensionParameters.ToArray());
+            return DataContextStack.Create(childType, dataContextType, extensionParameters: extensionParameters.ToArray(), serverSideOnly: serverOnly);
         }
 
-        public static (Type? type, List<BindingExtensionParameter> extensionParameters, bool addLayer) ApplyDataContextChange(DataContextStack dataContext, DataContextChangeAttribute[] attributes, ResolvedControl control, DotvvmProperty? property)
+        public static (Type? type, List<BindingExtensionParameter> extensionParameters, bool addLayer, bool serverOnly) ApplyDataContextChange(DataContextStack dataContext, DataContextChangeAttribute[] attributes, ResolvedControl control, DotvvmProperty? property)
         {
             var type = ResolvedTypeDescriptor.Create(dataContext.DataContextType);
             var extensionParameters = new List<BindingExtensionParameter>();
             var addLayer = false;
+            var serverOnly = dataContext.ServerSideOnly;
+
             foreach (var attribute in attributes.OrderBy(a => a.Order))
             {
                 if (type == null) break;
@@ -459,17 +482,19 @@ public static (Type? type, List<BindingExtensionParameter> extensionParameters,
                 {
                     addLayer = true;
                     type = attribute.GetChildDataContextType(type, dataContext, control, property);
+                    serverOnly = attribute.IsServerSideOnly(dataContext, control, property) ?? serverOnly;
                 }
             }
-            return (ResolvedTypeDescriptor.ToSystemType(type), extensionParameters, addLayer);
+            return (ResolvedTypeDescriptor.ToSystemType(type), extensionParameters, addLayer, serverOnly);
         }
 
 
-        private static (Type? childType, List<BindingExtensionParameter> extensionParameters, bool addLayer) ApplyDataContextChange(DataContextStack dataContextType, DataContextChangeAttribute[] attributes, DotvvmBindableObject obj, DotvvmProperty property)
+        private static (Type? childType, List<BindingExtensionParameter> extensionParameters, bool addLayer, bool serverOnly) ApplyDataContextChange(DataContextStack dataContextType, DataContextChangeAttribute[] attributes, DotvvmBindableObject obj, DotvvmProperty property)
         {
             Type? type = dataContextType.DataContextType;
             var extensionParameters = new List<BindingExtensionParameter>();
             var addLayer = false;
+            var serverOnly = dataContextType.ServerSideOnly;
 
             foreach (var attribute in attributes.OrderBy(a => a.Order))
             {
@@ -479,10 +504,11 @@ private static (Type? childType, List<BindingExtensionParameter> extensionParame
                 {
                     addLayer = true;
                     type = attribute.GetChildDataContextType(type, dataContextType, obj, property);
+                    serverOnly = attribute.IsServerSideOnly(dataContextType, obj, property) ?? serverOnly;
                 }
             }
 
-            return (type, extensionParameters, addLayer);
+            return (type, extensionParameters, addLayer, serverOnly);
         }
 
         /// <summary>

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/ConstantDataContextChangeAttribute.cs

@@ -15,11 +15,13 @@ public class ConstantDataContextChangeAttribute : DataContextChangeAttribute
         public Type Type { get; }
 
         public override int Order { get; }
+        public bool? ServerSideOnly { get; }
 
-        public ConstantDataContextChangeAttribute(Type type, int order = 0)
+        public ConstantDataContextChangeAttribute(Type type, int order = 0, bool? serverSideOnly = null)
         {
             Type = type;
             Order = order;
+            ServerSideOnly = serverSideOnly;
         }
 
         public override ITypeDescriptor? GetChildDataContextType(ITypeDescriptor dataContext, IDataContextStack controlContextStack, IAbstractControl control, IPropertyDescriptor? property = null)
@@ -31,5 +33,10 @@ public ConstantDataContextChangeAttribute(Type type, int order = 0)
         {
             return Type;
         }
+
+        public override bool? IsServerSideOnly(IDataContextStack controlContextStack, IAbstractControl control, IPropertyDescriptor? property = null) =>
+            ServerSideOnly;
+        public override bool? IsServerSideOnly(DataContextStack controlContextStack, DotvvmBindableObject control, DotvvmProperty? property = null) =>
+            ServerSideOnly;
     }
 }

src/Framework/Framework/Binding/ControlPropertyBindingDataContextChangeAttribute.cs

@@ -7,6 +7,8 @@
 using DotVVM.Framework.Binding.Expressions;
 using DotVVM.Framework.Compilation.ControlTree;
 using DotVVM.Framework.Controls;
+using DotVVM.Framework.Utils;
+using FastExpressionCompiler;
 
 namespace DotVVM.Framework.Binding
 {
@@ -65,17 +67,16 @@ void ThrowDataContextMismatch(IAbstractBinding binding)
         public override Type? GetChildDataContextType(Type dataContext, DataContextStack controlContextStack, DotvvmBindableObject control, DotvvmProperty? property = null)
         {
             var controlType = control.GetType();
-            var controlPropertyField = controlType.GetField($"{PropertyName}Property", BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy);
-            var controlProperty = (DotvvmProperty?)controlPropertyField?.GetValue(null);
+            var controlProperty = DotvvmProperty.ResolveProperty(controlType, PropertyName);
 
             if (controlProperty == null)
             {
-                throw new Exception($"The property '{PropertyName}' was not found on control '{controlType}'!");
+                throw new Exception($"The property '{PropertyName}' was not found on control '{controlType.ToCode()}'!");
             }
 
             if (control.properties.Contains(controlProperty))
             {
-                return control.GetValueBinding(controlProperty) is IValueBinding valueBinding
+                return control.GetBinding(controlProperty) is IStaticValueBinding valueBinding
                     ? valueBinding.ResultType
                     : dataContext;
             }
@@ -85,9 +86,32 @@ void ThrowDataContextMismatch(IAbstractBinding binding)
                 return dataContext;
             }
 
-            throw new Exception($"Property '{PropertyName}' is required on '{controlType.Name}'.");
+            throw new Exception($"Property '{PropertyName}' is required on '{controlType.ToCode()}'.");
         }
 
         public override IEnumerable<string> PropertyDependsOn => new[] { PropertyName };
+
+        public override bool? IsServerSideOnly(DataContextStack controlContextStack, DotvvmBindableObject control, DotvvmProperty? property = null)
+        {
+            var controlProperty = DotvvmProperty.ResolveProperty(control.GetType(), PropertyName);
+            if (controlProperty is null)
+                return null;
+
+            var binding = control.GetBinding(controlProperty);
+            return binding is not IValueBinding or null;
+        }
+
+        public override bool? IsServerSideOnly(IDataContextStack controlContextStack, IAbstractControl control, IPropertyDescriptor? property = null)
+        {
+            if (!control.Metadata.TryGetProperty(PropertyName, out var controlProperty))
+                return null;
+            if (!control.TryGetProperty(controlProperty, out var setter))
+                return null;
+
+            return
+                setter is IAbstractPropertyBinding { Binding.BindingType: var bindingType } &&
+                !typeof(IValueBinding).IsAssignableFrom(bindingType);
+
+        }
     }
 }

src/Framework/Framework/Binding/ControlPropertyTypeDataContextChangeAttribute.cs

@@ -47,7 +47,7 @@ public ControlPropertyTypeDataContextChangeAttribute(string propertyName, int or
                 throw new Exception($"The property '{PropertyName}' was not found on control '{controlType}'!");
             }
 
-            if (control.properties.Contains(controlProperty) && control.GetValueBinding(controlProperty) is IValueBinding valueBinding)
+            if (control.properties.Contains(controlProperty) && control.GetBinding(controlProperty) is IStaticValueBinding valueBinding)
             {
                 return valueBinding.ResultType;
             }

src/Framework/Framework/Binding/DataContextChangeAttribute.cs

@@ -34,6 +34,11 @@ public abstract class DataContextChangeAttribute : Attribute
         /// Gets the extension parameters that should be made available to the bindings inside.
         public virtual IEnumerable<BindingExtensionParameter> GetExtensionParameters(ITypeDescriptor dataContext) => Enumerable.Empty<BindingExtensionParameter>();
 
+        /// <summary> Gets if the nested data context is available only on server or also client-side, controls the <see cref="DataContextStack.ServerSideOnly" /> property. `null` means that it should be inherited from the parent context. </summary>
+        public virtual bool? IsServerSideOnly(IDataContextStack controlContextStack, IAbstractControl control, IPropertyDescriptor? property = null) => null;
+        /// <summary> Gets if the nested data context is available only on server or also client-side, controls the <see cref="DataContextStack.ServerSideOnly" /> property. `null` means that it should be inherited from the parent context. </summary>
+        public virtual bool? IsServerSideOnly(DataContextStack controlContextStack, DotvvmBindableObject control, DotvvmProperty? property = null) => null;
+
         /// Gets a list of attributes that need to be resolved before this attribute is invoked.
         public virtual IEnumerable<string> PropertyDependsOn => Enumerable.Empty<string>();
     }

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))
                 }));
         }