Merge pull request #6350 from elsa-workflows/bug/complex_type_array_s…

…erialization

Improve JSON array conversion in ObjectConverter

src/modules/Elsa.Expressions/Elsa.Expressions.csproj

@@ -15,6 +15,7 @@
 
     <ItemGroup>
       <ProjectReference Include="..\..\common\Elsa.Features\Elsa.Features.csproj" />
+      <ProjectReference Include="..\Elsa.Common\Elsa.Common.csproj" />
     </ItemGroup>
 
 </Project>

src/modules/Elsa.Expressions/Helpers/ObjectConverter.cs

@@ -102,15 +102,29 @@ public static Result TryConvertTo(this object? value, Type targetType, ObjectCon
             return jsonElement.Deserialize(targetType, serializerOptions);
         }
 
-        if (value is JsonNode jsonNode and not JsonArray) // If the value is a JsonNode, we can convert it to the target type. If it's a JsonArray, we let the enumerable conversion logic handle it.
+        if (value is JsonNode jsonNode)
         {
-            return underlyingTargetType switch
+            if (jsonNode is not JsonArray jsonArray)
             {
-                { } t when t == typeof(string) => jsonNode.ToString(),
-                { } t when t == typeof(ExpandoObject) && jsonNode.GetValueKind() == JsonValueKind.Object => JsonSerializer.Deserialize<ExpandoObject>(jsonNode.ToJsonString()),
-                { } t when t != typeof(object) || converterOptions?.DeserializeJsonObjectToObject == true => jsonNode.Deserialize(targetType, serializerOptions),
-                _ => jsonNode
-            };
+                return underlyingTargetType switch
+                {
+                    { } t when t == typeof(string) => jsonNode.ToString(),
+                    { } t when t == typeof(ExpandoObject) && jsonNode.GetValueKind() == JsonValueKind.Object => JsonSerializer.Deserialize<ExpandoObject>(jsonNode.ToJsonString()),
+                    { } t when t != typeof(object) || converterOptions?.DeserializeJsonObjectToObject == true => jsonNode.Deserialize(targetType, serializerOptions),
+                    _ => jsonNode
+                };
+            }
+
+            // Convert to target type if target type is an array or a generic collection.
+            if (targetType.IsArray || targetType.IsCollectionType())
+            {
+                // The element type of the source array is JsonObject. If the element type of the target array is Object then return the source array as an array of JsonObjects.
+                // Deserializing normally would return an array of JsonElement instead of JsonObject, but we want to keep JsonObject elements:
+                var targetElementType = targetType.IsArray ? targetType.GetElementType()! : targetType.GenericTypeArguments[0];
+
+                if (targetElementType != typeof(object))
+                    return jsonArray.Deserialize(targetType, serializerOptions);
+            }
         }
 
         if (underlyingSourceType == typeof(string) && !underlyingTargetType.IsPrimitive && underlyingTargetType != typeof(object))

test/unit/Elsa.Workflows.Core.UnitTests/ObjectConversion/Person.cs

@@ -0,0 +1,9 @@
+namespace Elsa.Workflows.Core.UnitTests.ObjectConversion
+{
+    public class Person
+    {
+        public double? Age { get; set; }
+
+        public string? Name { get; set; }
+    }
+}

test/unit/Elsa.Workflows.Core.UnitTests/ObjectConversion/Tests.cs

@@ -283,4 +283,21 @@ public void ConvertTo_JsonArrayToICollectionOfObject_ReturnsCollectionOfJsonObje
         Assert.Equal("Bob", secondElement["name"]?.ToString());
         Assert.Equal("25", secondElement["age"]?.ToString());
     }
+
+    [Fact]
+    public void ConvertFrom_JsonArrayToArrayOfComplextType_ReturnsArrayOfComplexType()
+    {
+        // Arrange
+        var jsonArrayString = "[{\"name\":\"Alice\",\"age\":30},{\"name\":\"Bob\",\"age\":25}]";
+        var options = new ObjectConverterOptions();
+
+        // Act
+        var result = jsonArrayString.ConvertTo<Person[]>(options);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Equal(2, result.Length);
+        Assert.Equal("Alice", result[0].Name);
+        Assert.Equal("Bob", result[1].Name);
+    }
 }