Fixes: U4-4368 Cannot insert the value NULL into column 'name' when creating new relation type from API

src/Umbraco.Core/Models/RelationType.cs

@@ -21,9 +21,18 @@ namespace Umbraco.Core.Models
 
         public RelationType(Guid childObjectType, Guid parentObjectType, string @alias)
         {
+            Mandate.ParameterNotNullOrEmpty(@alias, "alias");
             _childObjectType = childObjectType;
             _parentObjectType = parentObjectType;
             _alias = alias;
+            Name = _alias;
+        }
+
+        public RelationType(Guid childObjectType, Guid parentObjectType, string @alias, string name)
+            :this(childObjectType, parentObjectType, @alias)
+        {
+            Mandate.ParameterNotNullOrEmpty(name, "name");
+            Name = name;
         }
 
         private static readonly PropertyInfo NameSelector = ExpressionHelper.GetPropertyInfo<RelationType, string>(x => x.Name);

src/Umbraco.Tests/Services/ContentServiceTests.cs

@@ -14,7 +14,7 @@ using Umbraco.Tests.TestHelpers.Entities;
 
 namespace Umbraco.Tests.Services
 {
-	/// <summary>
+    /// <summary>
     /// Tests covering all methods in the ContentService class.
     /// This is more of an integration test as it involves multiple layers
     /// as well as configuration.

src/Umbraco.Tests/Services/RelationServiceTests.cs

@@ -0,0 +1,34 @@
+using System;
+using NUnit.Framework;
+using Umbraco.Core;
+using Umbraco.Core.Models;
+
+namespace Umbraco.Tests.Services
+{
+    [TestFixture, RequiresSTA]
+    public class RelationServiceTests : BaseServiceTest
+    {
+        [SetUp]
+        public override void Initialize()
+        {
+            base.Initialize();
+        }
+
+        [TearDown]
+        public override void TearDown()
+        {
+            base.TearDown();
+        }
+
+        [Test]
+        public void Can_Create_RelationType_Without_Name()
+        {
+            var rs = ServiceContext.RelationService;
+            var rt = new RelationType(new Guid(Constants.ObjectTypes.Document), new Guid(Constants.ObjectTypes.Document), "repeatedEventOccurence");
+
+            Assert.DoesNotThrow(() => rs.Save(rt));
+
+            Assert.AreEqual(rt.Name, "repeatedEventOccurence");
+        }
+    }
+}

src/Umbraco.Tests/Umbraco.Tests.csproj

@@ -234,6 +234,7 @@
     <Compile Include="Services\MemberTypeServiceTests.cs" />
     <Compile Include="Services\PackagingServiceTests.cs" />
     <Compile Include="Services\PerformanceTests.cs" />
+    <Compile Include="Services\RelationServiceTests.cs" />
     <Compile Include="Services\UserServiceTests.cs" />
     <Compile Include="TestHelpers\BaseSeleniumTest.cs" />
     <Compile Include="Integration\InstallPackage.cs" />