Added OnChanged functionality

rrmanzano · Apr 12, 2022 · ba73b7b · ba73b7b
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diff --git a/README.md b/README.md
@@ -1,4 +1,4 @@
-[![NuGet](http://img.shields.io/nuget/vpre/M.BindableProperty.Generator.svg?label=NuGet)](https://www.nuget.org/packages/M.BindableProperty.Generator/)
+[![NuGet](http://img.shields.io/nuget/vpre/M.BindableProperty.Generator.svg?label=NuGet)](https://www.nuget.org/packages/M.BindableProperty.Generator/) [![GitHub issues](https://img.shields.io/github/issues/rrmanzano/maui-bindableproperty-generator?style=flat-square)](https://github.com/rrmanzano/maui-bindableproperty-generator/) [![GitHub stars](https://img.shields.io/github/stars/rrmanzano/maui-bindableproperty-generator?style=flat-square)](https://github.com/rrmanzano/maui-bindableproperty-generator/stargazers) ![last commit](https://img.shields.io/github/last-commit/rrmanzano/maui-bindableproperty-generator?style=flat-square)
 
 # Maui.BindableProperty.Generator
 
@@ -60,13 +60,47 @@ the prevoius code will generate this:
     }
 ```
 
+## Usage - OnChanged method 
+Just decorate field with the Bindable attribute. The 'OnChanged' method must have only one parameter (must match the type of the field)
+
+```csharp
+    using Maui.BindableProperty.Generator.Core;
+
+    public partial class CustomEntry : ContentView
+    {
+        [AutoBindable(OnChanged = nameof(OnTextChanged))]
+        private string _text;
+
+        private void OnTextChanged(string newValue)
+        { 
+            // Do stuff here
+        }
+    }
+```
+the prevoius code will generate this:
+```csharp
+    public partial class CustomEntry
+    {
+        public static readonly Microsoft.Maui.Controls.BindableProperty TextProperty = Microsoft.Maui.Controls.BindableProperty.Create(nameof(Text), typeof(string), typeof(CustomEntry), default(string));
+        public string Text
+        {
+            get => (string)GetValue(TextProperty);
+            set =>
+            {
+                SetValue(TextProperty, value);
+                this.OnTextChanged(value);
+            }
+        }
+    }
+```
+
 ## Project status
 
 - ✅ Simple implementation - Done
 - ✅ Custom property name - Done
 - 🔲 Custom Parameters - In Progress
-- 🔲 OnChanged method - Pending
-- 🔲 Dependent properties - Pending
+- ✅ OnChanged method - Done
+- 🔲 Property Accessibility - Pending
 
 ## Extra info
-This repo is using part of the code of this repo [CodeWriter](https://github.com/SaladLab/CodeWriter "CodeWriter") to generate the CSharp files, thanks to the author.
+This repo is using part of the code of [CodeWriter](https://github.com/SaladLab/CodeWriter "CodeWriter") to generate the CSharp files, thanks to the author.
diff --git a/src/Maui.BindableProperty.Generator.Demo/Controls/CustomEntry.cs b/src/Maui.BindableProperty.Generator.Demo/Controls/CustomEntry.cs
@@ -8,7 +8,12 @@ public partial class CustomEntry: ContentView
         private string _placeholder;
 
 
-        [AutoBindable(PropertyName = "Text")]
-        private string _t;
+        [AutoBindable(OnChanged = nameof(OnTextChanged))]
+        private string _text;
+
+        private void OnTextChanged(string newValue)
+        {
+            // Do stuff here
+        }
     }
 }
diff --git a/src/Maui.BindableProperty.Generator/Core/BindableProperty/AutoBindablePropertyGenerator.cs b/src/Maui.BindableProperty.Generator/Core/BindableProperty/AutoBindablePropertyGenerator.cs
@@ -21,6 +21,8 @@ public sealed class AutoBindableAttribute : Attribute
                 public AutoBindableAttribute(){}
 
                 public string PropertyName { get; set; }
+
+                public string OnChanged { get; set; }
             }
         }";
 
@@ -65,9 +67,15 @@ private void ProcessBindableProperty(CodeWriter w, IFieldSymbol fieldSymbol, ISy
 
             // Get the AutoNotify attribute from the field, and any associated data
             var attributeData = fieldSymbol.GetAttributes().Single(ad => ad.AttributeClass.Equals(attributeSymbol, SymbolEqualityComparer.Default));
-            var overridenNameOpt = attributeData.NamedArguments.SingleOrDefault(kvp => kvp.Key == "PropertyName").Value;
+            TypedConstant GetValue(string key)
+            {
+                return attributeData.NamedArguments.SingleOrDefault(kvp => kvp.Key == key).Value;
+            }
 
-            var propertyName = this.ChooseName(fieldName, overridenNameOpt);
+            var overridenNameProperty = GetValue("PropertyName");
+            var overridenOnChanged = GetValue("OnChanged");
+
+            var propertyName = this.ChooseName(fieldName, overridenNameProperty);
             if (propertyName?.Length == 0 || propertyName == fieldName)
             {
                 // TODO: issue a diagnostic that we can't process this field
@@ -80,8 +88,20 @@ private void ProcessBindableProperty(CodeWriter w, IFieldSymbol fieldSymbol, ISy
             w._(AutoBindableConstants.AttributeGeneratedCodeString);
             using (w.B(@$"public {fieldType} {propertyName}"))
             {
-                w._($@"get => ({fieldType})GetValue({bindablePropertyName});",
-                    $@"set => SetValue({bindablePropertyName}, value);");
+                w._($@"get => ({fieldType})GetValue({bindablePropertyName});");
+                if (!overridenOnChanged.IsNull)
+                {
+                    var method = overridenOnChanged.Value?.ToString();
+                    using (w.B(@$"set"))
+                    {
+                        w._($@"SetValue({bindablePropertyName}, value);",
+                            $@"this.{method}(value);");
+                    }
+                }
+                else
+                {
+                    w._($@"set => SetValue({bindablePropertyName}, value);");
+                }
             }
         }
 

diff --git a/src/Maui.BindableProperty.Generator/Maui.BindableProperty.Generator.csproj b/src/Maui.BindableProperty.Generator/Maui.BindableProperty.Generator.csproj
@@ -10,7 +10,7 @@
 		<Description>Source generator that automatically transforms fields into BindableProperties that can be used in MAUI</Description>
 		<PackageTags>MAUI;BindableProperty;Source Generator</PackageTags>
 		<PackageReadmeFile>README.md</PackageReadmeFile>
-		<VersionPrefix>0.3.3</VersionPrefix>
+		<VersionPrefix>0.4.0</VersionPrefix>
 		<PackageProjectUrl>https://github.com/rrmanzano/maui-bindableproperty-generator</PackageProjectUrl>
 		<RepositoryUrl>https://github.com/rrmanzano/maui-bindableproperty-generator</RepositoryUrl>
 		<PackageId>M.BindableProperty.Generator</PackageId>