Fix: Improve ObservableAsPropertyAttribute with string (#376)

ChrisPulman · web-flow · commit 0a67b637c458 · 2026-01-26T10:23:40.000+11:00
* Improve ObservableAsPropertyAttribute with string

Introduces the PLCInstance class to represent a PLC in the application. Updates TestViewModel to include reactive and observable properties for PLC instance, active status, and port, with initial values. Improves ObservableAsPropertyAttribute documentation and initial value handling in source generator. Updates solution file format from .sln to .slnx.

* Fix string type check for property initialization

Updated the property type check to use EndsWith("##string") and EndsWith("##string?") instead of direct equality. This ensures correct initialization for string properties with type suffixes.
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,11 +41,10 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethods#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethods#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,11 +41,10 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethodsWithName#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethodsWithName#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,11 +41,10 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableProp#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableProp#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropNestedClasses#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropNestedClasses#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithAttribute#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithAttribute#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithAttributeNullableRef#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithAttributeNullableRef#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithAttributeRef#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithAttributeRef#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithName#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservablePropertiesWithName#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromPartialProperty#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromPartialProperty#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.FromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.FromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,11 +41,10 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.FromFieldNestedClass#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.FromFieldNestedClass#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,11 +41,10 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.NamedFromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.NamedFromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.NonReadOnlyFromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.NonReadOnlyFromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.NonReadOnlyFromFieldProtected#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs b/src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPGeneratorTests.NonReadOnlyFromFieldProtected#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs
@@ -41,12 +41,11 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
-#pragma warning restore
+#pragma warning restore
diff --git a/src/ReactiveUI.SourceGenerators.Analyzers.CodeFixes/Diagnostics/DiagnosticDescriptors.cs b/src/ReactiveUI.SourceGenerators.Analyzers.CodeFixes/Diagnostics/DiagnosticDescriptors.cs
@@ -19,12 +19,12 @@ internal static class DiagnosticDescriptors
     /// </summary>
     public static readonly DiagnosticDescriptor PropertyToReactiveFieldRule = new(
         id: "RXUISG0016",
-        title: "Property To Reactive Field, change to [Reactive] private type _fieldName;",
+        title: "Property To Reactive Field, change to `[Reactive]` private type _fieldName;",
         messageFormat: "Replace the property with a INPC Reactive Property for ReactiveUI",
         category: typeof(PropertyToReactiveFieldAnalyzer).FullName,
         defaultSeverity: DiagnosticSeverity.Info,
         isEnabledByDefault: true,
-        description: "Used to create a Read Write INPC Reactive Property for ReactiveUI, annotated with [Reactive].",
+        description: "Used to create a Read Write INPC Reactive Property for ReactiveUI, annotated with `[Reactive]`.",
         helpLinkUri: "https://www.reactiveui.net/docs/handbook/view-models/boilerplate-code.html");
 
     /// <summary>
@@ -33,7 +33,7 @@ internal static class DiagnosticDescriptors
     public static readonly DiagnosticDescriptor ReactiveAttributeRequiresPartialRule = new(
         id: "RXUISG0020",
         title: "[Reactive] requires partial property and containing type",
-        messageFormat: "`[Reactive]` requires the property to be `partial` and the containing type to be `partial` so source generation can run.",
+        messageFormat: "`[Reactive]` requires the property to be `partial` and the containing type to be partial so source generation can run",
         category: typeof(ReactiveAttributeMisuseAnalyzer).FullName,
         defaultSeverity: DiagnosticSeverity.Warning,
         isEnabledByDefault: true,
diff --git a/src/ReactiveUI.SourceGenerators.Execute/PLCInstance.cs b/src/ReactiveUI.SourceGenerators.Execute/PLCInstance.cs
@@ -0,0 +1,33 @@
+﻿// Copyright (c) 2026 ReactiveUI and contributors. All rights reserved.
+// Licensed to the ReactiveUI and contributors under one or more agreements.
+// The ReactiveUI and contributors licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+namespace SGReactiveUI.SourceGenerators.Test;
+
+/// <summary>
+/// Represents a programmable logic controller (PLC) instance within the application.
+/// </summary>
+public class PLCInstance
+{
+    /// <summary>
+    /// Gets or sets the unique identifier for the PLC instance.
+    /// </summary>
+    public int Id { get; set; }
+    /// <summary>
+    /// Gets or sets the name of the PLC instance.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+    /// <summary>
+    /// Gets or sets the IP address of the PLC instance.
+    /// </summary>
+    public string IPAddress { get; set; } = string.Empty;
+    /// <summary>
+    /// Gets or sets a value indicating whether the PLC instance is currently active.
+    /// </summary>
+    public bool IsActive { get; set; }
+    /// <summary>
+    /// Gets or sets the network port number used for the connection.
+    /// </summary>
+    public int Port { get; set; }
+}
diff --git a/src/ReactiveUI.SourceGenerators.Execute/TestViewModel.cs b/src/ReactiveUI.SourceGenerators.Execute/TestViewModel.cs
@@ -78,6 +78,9 @@ public partial class TestViewModel : ReactiveObject, IActivatableViewModel, IDis
     [Reactive]
     private double _myDoubleNonNullProperty;
 
+    [Reactive]
+    private PLCInstance _plcInstanceCore = new();
+
     [BindableDerivedList]
     private ReadOnlyObservableCollection<Person>? _visiblePeople;
 
@@ -211,6 +214,10 @@ public TestViewModel()
             .Bind(out _visiblePeople)
             .Subscribe());
 
+        _pLCActiveHelper = this.WhenAnyValue(x => x.PartialRequiredPropertyTest).ToProperty(this, nameof(PLCActive));
+        _pLCPortHelper = this.WhenAnyValue(x => x.Test1Property).ToProperty(this, nameof(PLCPort));
+        _instanceOfPLCHelper = this.WhenAnyValue(x => x.PlcInstanceCore).ToProperty(this, nameof(InstanceOfPLC));
+
         Console.ReadLine();
     }
 
@@ -319,6 +326,24 @@ public TestViewModel()
     [property: Test(AParameter = "Test Input")]
     public IObservable<int> ObservableAsPropertyTest2 => Observable.Return(9);
 
+    /// <summary>
+    /// Gets the current active PLC identifier or name.
+    /// </summary>
+    [ObservableAsProperty(InitialValue = "Not Connected")]
+    public partial string? PLCActive { get; }
+
+    /// <summary>
+    /// Gets the TCP port number used to communicate with the PLC.
+    /// </summary>
+    [ObservableAsProperty(InitialValue = "9000")]
+    public partial int PLCPort { get; }
+
+    /// <summary>
+    /// Gets the current instance of the PLC (Programmable Logic Controller) used by the application.
+    /// </summary>
+    [ObservableAsProperty(InitialValue = $"new {nameof(PLCInstance)}()")]
+    public partial PLCInstance InstanceOfPLC { get; }
+
     /// <summary>
     /// Gets the Activator which will be used by the View when Activation/Deactivation occurs.
     /// </summary>
diff --git a/src/ReactiveUI.SourceGenerators.Roslyn/AttributeDefinitions.cs b/src/ReactiveUI.SourceGenerators.Roslyn/AttributeDefinitions.cs
@@ -320,11 +320,10 @@ internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
     public bool UseProtected { get; init; } = false;
 
     /// <summary>
-    /// Gets the Initial value of the OAPH property.
+    /// Gets the Initial Value of the OAPH property. 
+    /// This should be a string representation of the value. i.e. "42" or "DateTime.Now" or "new List&lt;string&gt;()".
+    /// String values are automatically quoted.
     /// </summary>
-    /// <value>
-    /// The initial value of the OAPH property.
-    /// </value>
     public string? InitialValue { get; init; }
 }
 #nullable restore
diff --git a/src/ReactiveUI.SourceGenerators.Roslyn/ObservableAsProperty/ObservableAsPropertyGenerator{FromObservable}.Execute.cs b/src/ReactiveUI.SourceGenerators.Roslyn/ObservableAsProperty/ObservableAsPropertyGenerator{FromObservable}.Execute.cs
diff --git a/src/ReactiveUI.SourceGenerators.Roslyn/Reactive/ReactiveGenerator.Execute.cs b/src/ReactiveUI.SourceGenerators.Roslyn/Reactive/ReactiveGenerator.Execute.cs
diff --git a/src/ReactiveUI.SourceGenerators.sln b/src/ReactiveUI.SourceGenerators.sln
diff --git a/src/ReactiveUI.SourceGenerators.slnx b/src/ReactiveUI.SourceGenerators.slnx
