Improve error handling of CommandResolver: missing markup control

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

@@ -6,6 +6,7 @@
 using System.Runtime.CompilerServices;
 using DotVVM.Framework.Compilation.ControlTree.Resolved;
 using DotVVM.Framework.Utils;
+using FastExpressionCompiler;
 
 namespace DotVVM.Framework.Compilation.ControlTree
 {
@@ -167,12 +168,12 @@ int ComputeHashCode()
         public override string ToString()
         {
             string?[] features = new [] {
-                $"type={this.DataContextType.FullName}",
+                $"type={this.DataContextType.ToCode()}",
                 this.ServerSideOnly ? "server-side-only" : null,
                 this.NamespaceImports.Any() ? "imports=[" + string.Join(", ", this.NamespaceImports) + "]" : null,
                 this.ExtensionParameters.Any() ? "ext=[" + string.Join(", ", this.ExtensionParameters.Select(e => e.Identifier + ": " + e.ParameterType.Name)) + "]" : null,
                 this.BindingPropertyResolvers.Any() ? "resolvers=[" + string.Join(", ", this.BindingPropertyResolvers.Select(s => s.Method)) + "]" : null,
-                this.Parent != null ? "par=[" + string.Join(", ", this.Parents().Select(p => p.Name)) + "]" : null
+                this.Parent != null ? "par=[" + string.Join(", ", this.Parents().Select(p => p.ToCode(stripNamespace: true))) + "]" : null
             };
             return "(" + features.Where(a => a != null).StringJoin(", ") + ")";
         }

src/Framework/Framework/Controls/DotvvmControlProperties.cs

@@ -388,9 +388,11 @@ public DotvvmPropertyDictionary(DotvvmBindableObject control)
 
         public object? this[DotvvmProperty key] { get => control.properties.GetOrThrow(key); set => control.properties.Set(key, value); }
 
-        public ICollection<DotvvmProperty> Keys => throw new NotImplementedException();
+        public KeysCollection Keys => new KeysCollection(control);
+        ICollection<DotvvmProperty> IDictionary<DotvvmProperty, object?>.Keys => Keys;
 
-        public ICollection<object?> Values => throw new NotImplementedException();
+        public ValuesCollection Values => new ValuesCollection(control);
+        ICollection<object?> IDictionary<DotvvmProperty, object?>.Values => Values;
 
         public int Count => control.properties.Count();
         public bool IsReadOnly => false;
@@ -442,5 +444,72 @@ public bool TryGetValue(DotvvmProperty key, out object? value) =>
         IEnumerator IEnumerable.GetEnumerator() => this.GetEnumerator();
 
         IEnumerator<KeyValuePair<DotvvmProperty, object?>> IEnumerable<KeyValuePair<DotvvmProperty, object?>>.GetEnumerator() => this.GetEnumerator();
+
+
+        public readonly struct KeysCollection : ICollection<DotvvmProperty>, IReadOnlyCollection<DotvvmProperty>
+        {
+            private readonly DotvvmBindableObject control;
+
+            public KeysCollection(DotvvmBindableObject control) { this.control = control; }
+            public int Count => control.properties.Count();
+
+            public bool IsReadOnly => true;
+            public void Add(DotvvmProperty item) => throw new NotSupportedException("Adding a property without value doesn't make sense");
+            public void Clear() => throw new NotSupportedException("Explicitly use control.Properties.Clear() instead.");
+            public bool Contains(DotvvmProperty item) => control.properties.Contains(item);
+            public void CopyTo(DotvvmProperty[] array, int arrayIndex)
+            {
+                foreach (var x in control.properties)
+                {
+                    array[arrayIndex++] = x.Key;
+                }
+            }
+            public IEnumerator<DotvvmProperty> GetEnumerator()
+            {
+                foreach (var x in control.properties)
+                {
+                    yield return x.Key;
+                }
+            }
+            public bool Remove(DotvvmProperty item) => throw new NotSupportedException("Explicitly use control.Properties.Remove() instead.");
+            IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+        }
+
+        public struct ValuesCollection : ICollection<object?>
+        {
+            private readonly DotvvmBindableObject control;
+
+            public ValuesCollection(DotvvmBindableObject control) { this.control = control; }
+            public int Count => control.properties.Count();
+
+            public bool IsReadOnly => true;
+            public void Add(object? item) => throw new NotSupportedException("Adding a value without property doesn't make sense");
+            public void Clear() => throw new NotSupportedException("Explicitly use control.Properties.Clear() instead.");
+            public bool Contains(object? item)
+            {
+                foreach (var x in control.properties)
+                {
+                    if (Object.Equals(x.Value, item))
+                        return true;
+                }
+                return false;
+            }
+            public void CopyTo(object?[] array, int arrayIndex)
+            {
+                foreach (var x in control.properties)
+                {
+                    array[arrayIndex++] = x.Value;
+                }
+            }
+            public IEnumerator<object?> GetEnumerator()
+            {
+                foreach (var x in control.properties)
+                {
+                    yield return x.Value;
+                }
+            }
+            public bool Remove(object? item) => throw new NotSupportedException("Explicitly use control.Properties.Remove() instead.");
+            IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+        }
     }
 }

src/Framework/Framework/ViewModel/Serialization/DefaultViewModelSerializer.cs

@@ -382,7 +382,13 @@ public void PopulateViewModel(IDotvvmRequestContext context, string serializedPo
                 var target = view.FindControlByUniqueId(controlUniqueId);
                 if (target == null)
                 {
-                    throw new Exception(string.Format("The control with ID '{0}' was not found!", controlUniqueId));
+                    var markupControls =
+                        view.GetAllDescendants()
+                            .OfType<DotvvmMarkupControl>()
+                            .Where(c => c.GetAllDescendants(cc => cc is not DotvvmMarkupControl)
+                                         .Any(cc => cc.Properties.Values
+                                                      .Any(value => value is Binding.Expressions.CommandBindingExpression cb && cb.BindingId == command)));
+                    throw new Exception($"The control with ID '{controlUniqueId}' was not found! Existing markup controls with this command are: {string.Join(", ", markupControls.Select(c => c.GetDotvvmUniqueId().ToString()).OrderBy(s => s, StringComparer.Ordinal))}");
                 }
                 return commandResolver.GetFunction(target, view, context, path, command, args);
             }