From 835f080fae10ce8d651dca5cec40b2f4d4b053e6 Mon Sep 17 00:00:00 2001
From: Alexander Titov <atitov@i-gs.ru>
Date: Wed, 13 May 2020 11:45:11 +0300
Subject: [PATCH] Do not generate XmlElementAttribute IsNillable=true for
 collection property with non nullable element type

For XmlSerializer IsNillable=true is for collection element ant not for collection itself. Because we do not support Nullable<> for collection elements with non nullable datatypes then we must not generate IsNillable=true.

If we generate IsNillable=true for collectios with non nullable value types then XmlSerializer throws exception: 'System.InvalidOperationException: IsNullable may not be 'true' for value type System.DateTime.  Please consider using Nullable<System.DateTime> instead'
---
 XmlSchemaClassGenerator.Tests/XmlTests.cs | 40 ++++++++++++++++++++++-
 XmlSchemaClassGenerator/TypeModel.cs      |  2 +-
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/XmlSchemaClassGenerator.Tests/XmlTests.cs b/XmlSchemaClassGenerator.Tests/XmlTests.cs
index 1b3e70f0..bf4d8e90 100644
--- a/XmlSchemaClassGenerator.Tests/XmlTests.cs
+++ b/XmlSchemaClassGenerator.Tests/XmlTests.cs
@@ -1797,7 +1797,7 @@ public void AmbiguousAnonymousTypesTest()
                 {
                     GenerateNamespace = key =>key.XmlSchemaNamespace
                 }
-                , };
+            };
             var contents = ConvertXml(nameof(GenerateXmlRootAttributeForEnumTest), new[]{xsd1, xsd2}, generator).ToArray();
             Assert.Equal(2, contents.Length);
 
@@ -1842,5 +1842,43 @@ public void AmbiguousAnonymousTypesTest()
             Assert.Equal("TestType2Property", xmlRootAttribute.ElementName);
             Assert.Equal("Test_NS2", xmlRootAttribute.Namespace);
         }
+
+        [Fact]
+        public void TestShouldPatternForCollections()
+        {
+            const string xsd = @"<?xml version=""1.0"" encoding=""UTF-8""?>
+            <xs:schema xmlns:xs=""http://www.w3.org/2001/XMLSchema"" targetNamespace=""Test_NS1""
+            elementFormDefault=""qualified"" attributeFormDefault=""unqualified"">
+            <xs:element name=""TestType"">
+				<xs:complexType>
+					<xs:choice maxOccurs=""unbounded"">
+						<xs:element name=""DateValue"" type=""xs:dateTime"" nillable=""true""/>
+					</xs:choice>
+				</xs:complexType>
+            </xs:element>
+            <xs:element name=""TestType2"">
+				<xs:complexType>
+					<xs:choice maxOccurs=""unbounded"">
+						<xs:element name=""StringValue"" type=""xs:string"" nillable=""true""/>
+					</xs:choice>
+				</xs:complexType>
+            </xs:element>
+            </xs:schema>";
+
+            var generator = new Generator
+            {
+                NamespaceProvider = new NamespaceProvider
+                {
+                    GenerateNamespace = key => key.XmlSchemaNamespace
+                }
+            };
+
+            var contents = ConvertXml(nameof(TestShouldPatternForCollections), xsd, generator).ToArray();
+            Assert.Equal(1, contents.Length);
+            var assembly = Compiler.Compile(nameof(GenerateXmlRootAttributeForEnumTest), contents);
+            var testType = assembly.GetType("Test_NS1.TestType");
+            var serializer = new XmlSerializer(testType);
+            Assert.NotNull(serializer);
+        }
     }
 }
diff --git a/XmlSchemaClassGenerator/TypeModel.cs b/XmlSchemaClassGenerator/TypeModel.cs
index 3da80147..539673c2 100644
--- a/XmlSchemaClassGenerator/TypeModel.cs
+++ b/XmlSchemaClassGenerator/TypeModel.cs
@@ -1221,7 +1221,7 @@ private IEnumerable<CodeAttributeDeclaration> GetAttributes(bool isArray)
                     }
                 }
 
-                if (IsNillable)
+                if (IsNillable && !(IsCollection && Type is SimpleModel m && m.ValueType.IsValueType))
                 {
                     attribute.Arguments.Add(new CodeAttributeArgument("IsNullable", new CodePrimitiveExpression(true)));
                 }