Merge pull request #41 from koenbeuk/support-default-values

Support default parameter values

src/EntityFrameworkCore.Projectables.Generator/DeclarationSyntaxRewriter.cs

@@ -21,10 +21,17 @@ namespace EntityFrameworkCore.Projectables.Generator
 
             if (visitedNode is ParameterSyntax visitedParameterSyntax)
             {
+                // Strip the this keyword of any parameter
                 var thisKeywordIndex = visitedParameterSyntax.Modifiers.IndexOf(SyntaxKind.ThisKeyword);
                 if (thisKeywordIndex != -1)
                 {
-                    return visitedParameterSyntax.WithModifiers(node.Modifiers.RemoveAt(thisKeywordIndex));
+                    visitedNode = visitedParameterSyntax.WithModifiers(node.Modifiers.RemoveAt(thisKeywordIndex));
+                }
+
+                // Remove default values from parameters as this is not accepted in an expression tree
+                if (visitedParameterSyntax.Default is not null)
+                {
+                    visitedNode = ((ParameterSyntax)visitedNode).WithDefault(null);
                 }
             }
 

tests/EntityFrameworkCore.Projectables.FunctionalTests/DefaultValueTests.ExplicitDefaultValueIsSupported.verified.txt

@@ -0,0 +1,2 @@
+SELECT [e].[Id] + 2
+FROM [Entity] AS [e]

tests/EntityFrameworkCore.Projectables.FunctionalTests/DefaultValueTests.cs

@@ -0,0 +1,32 @@
+using EntityFrameworkCore.Projectables.FunctionalTests.Helpers;
+using Microsoft.EntityFrameworkCore;
+using System.Linq;
+using System.Threading.Tasks;
+using VerifyXunit;
+using Xunit;
+
+namespace EntityFrameworkCore.Projectables.FunctionalTests
+{
+    [UsesVerify]
+    public class DefaultValueTests
+    {
+        public record Entity
+        {
+            public int Id { get; set; }
+
+            [Projectable]
+            public int NextId(int skip = 1) => Id + skip;
+        }
+
+        [Fact]
+        public Task ExplicitDefaultValueIsSupported()
+        {
+            using var dbContext = new SampleDbContext<Entity>();
+
+            var query = dbContext.Set<Entity>()
+                .Select(x => x.NextId(2));
+
+            return Verifier.Verify(query.ToQueryString());
+        }
+    }
+}

tests/EntityFrameworkCore.Projectables.Generator.Tests/ProjectionExpressionGeneratorTests.DefaultValuesGetRemoved.verified.txt

@@ -0,0 +1,16 @@
+// <auto-generated/>
+using EntityFrameworkCore.Projectables;
+
+namespace EntityFrameworkCore.Projectables.Generated
+#nullable disable
+{
+    [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
+    public static class _Foo_Calculate
+    {
+        public static System.Linq.Expressions.Expression<System.Func<global::Foo ,int, int>> Expression()
+        {
+            return (global::Foo @this,int i ) => 
+                i;
+        }
+    }
+}

tests/EntityFrameworkCore.Projectables.Generator.Tests/ProjectionExpressionGeneratorTests.cs

@@ -1427,6 +1427,26 @@ class Derived : Base
             return Verifier.Verify(result.GeneratedTrees[0].ToString());
         }
 
+        [Fact]
+        public Task DefaultValuesGetRemoved()
+        {
+            var compilation = CreateCompilation(@"
+using EntityFrameworkCore.Projectables;
+
+class Foo {
+    [Projectable]
+    public int Calculate(int i = 0) => i;
+}
+");
+
+            var result = RunGenerator(compilation);
+
+            Assert.Empty(result.Diagnostics);
+            Assert.Single(result.GeneratedTrees);
+
+            return Verifier.Verify(result.GeneratedTrees[0].ToString());
+        }
+
         #region Helpers
 
         Compilation CreateCompilation(string source, bool expectedToCompile = true)