Multi-node picker: Validate content type when filter is configured but object type is not (closes #21338) (#21342)

Validate content type for multi-node picker when content types are defined but the object type is not (consider as being for a document).

Author: AndyButland

src/Umbraco.Infrastructure/PropertyEditors/MultiNodeTreePickerPropertyEditor.cs

@@ -3,8 +3,6 @@
 
 using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Nodes;
-using Microsoft.Extensions.DependencyInjection;
-using Umbraco.Cms.Core.DependencyInjection;
 using Umbraco.Cms.Core.IO;
 using Umbraco.Cms.Core.Models;
 using Umbraco.Cms.Core.Models.Editors;
@@ -348,18 +346,21 @@ public IEnumerable<ValidationResult> Validate(
 
                 Guid[] allowedTypes = configuration?.Filter?.Split(Constants.CharArrays.Comma, StringSplitOptions.RemoveEmptyEntries).Select(Guid.Parse).ToArray() ?? [];
 
-                // We can't validate if there is no object type, and we don't need to if there's no filter.
-                if (entityReferences is null || allowedTypes.Length == 0 || configuration?.TreeSource?.ObjectType is null)
+                // Don't need to validate if there's no filter.
+                if (entityReferences is null || allowedTypes.Length == 0)
                 {
                     return validationResults;
                 }
 
+                // If no object type is specified, it's considered as document.
+                var objectType = configuration?.TreeSource?.ObjectType ?? DocumentObjectType;
+
                 using ICoreScope scope = _coreScopeProvider.CreateCoreScope();
 
                 Guid?[] uniqueContentTypeKeys = entityReferences
                     .Select(x => x.Unique)
                     .Distinct()
-                    .Select(x => GetContent(configuration.TreeSource.ObjectType, x))
+                    .Select(x => GetContent(objectType, x))
                     .Select(x => x?.ContentType.Key)
                     .Distinct()
                     .ToArray();

tests/Umbraco.Tests.UnitTests/Umbraco.Core/PropertyEditors/MultiNodeTreePickerValidationTests.cs

@@ -135,10 +135,11 @@ public void Validates_Object_Type()
     [TestCase(false, false, true, MultiNodeTreePickerPropertyEditor.MultiNodeTreePickerPropertyValueEditor.DocumentObjectType)]
     [TestCase(false, false, true, MultiNodeTreePickerPropertyEditor.MultiNodeTreePickerPropertyValueEditor.MediaObjectType)]
     [TestCase(false, false, true, MultiNodeTreePickerPropertyEditor.MultiNodeTreePickerPropertyValueEditor.MemberObjectType)]
+    [TestCase(false, true, false, null)] // Null object type should be treated as being for document.
     [TestCase(false, true, false, MultiNodeTreePickerPropertyEditor.MultiNodeTreePickerPropertyValueEditor.DocumentObjectType)]
     [TestCase(false, true, false, MultiNodeTreePickerPropertyEditor.MultiNodeTreePickerPropertyValueEditor.MediaObjectType)]
     [TestCase(false, true, false, MultiNodeTreePickerPropertyEditor.MultiNodeTreePickerPropertyValueEditor.MemberObjectType)]
-    public void Validates_Allowed_Type(bool shouldSucceed, bool hasAllowedType, bool findsContent, string objectType)
+    public void Validates_Allowed_Type(bool shouldSucceed, bool hasAllowedType, bool findsContent, string? objectType)
     {
         var (valueEditor, _, contentService, mediaService, memberService) = CreateValueEditor();
 
@@ -170,7 +171,6 @@ public void Validates_Allowed_Type(bool shouldSucceed, bool hasAllowedType, bool
 
         var result = valueEditor.Validate(value, false, null, PropertyValidationContext.Empty());
         TestShouldSucceed(shouldSucceed, result);
-
     }
 
     private static (MultiNodeTreePickerPropertyEditor.MultiNodeTreePickerPropertyValueEditor ValueEditor,