Fix to get underlying type of nullable, list and dictionary object #113

Author: justinyoo

samples/Aliencube.AzureFunctions.FunctionApp.Models/DummySubResponseModel.cs

@@ -1,3 +1,5 @@
+using System.Collections.Generic;
+
 using Newtonsoft.Json;
 
 namespace Aliencube.AzureFunctions.FunctionApp.Models
@@ -8,5 +10,7 @@ public class DummySubResponseModel
 
         [JsonProperty("CapitalisedJsonRequiredValue", Required = Required.Always)]
         public string JsonRequiredValue { get; set; }
+
+        public Dictionary<string, List<int>> NestedDictionaryValue { get; set; }
     }
 }

src/Aliencube.AzureFunctions.Extensions.OpenApi.Core/Extensions/TypeExtensions.cs

@@ -351,6 +351,43 @@ public static bool IsGenericTypeOf(this Type t1, Type t2)
             return t1.IsGenericType && t1.GetGenericTypeDefinition() == t2;
         }
 
+        /// <summary>
+        /// Gets the underlying type of the given generic type.
+        /// </summary>
+        /// <param name="type">Type to check to get its underlying type.</param>
+        /// <returns>Returns the underlying type.</returns>
+        public static Type GetUnderlyingType(this Type type)
+        {
+            var underlyingType = default(Type);
+            if (type.IsOpenApiNullable(out var nullableUnderlyingType))
+            {
+                underlyingType = nullableUnderlyingType;
+            }
+
+            if (type.IsOpenApiArray())
+            {
+                underlyingType = type.GetElementType() ?? type.GetGenericArguments()[0];
+            }
+
+            if (type.IsOpenApiDictionary())
+            {
+                underlyingType = type.GetGenericArguments()[1];
+            }
+
+            if (underlyingType.IsNullOrDefault())
+            {
+                return underlyingType;
+            }
+
+            if (underlyingType.IsGenericType)
+            {
+                var underlyingTypeOfUnderlyingType = underlyingType.GetUnderlyingType();
+                underlyingType = underlyingTypeOfUnderlyingType;
+            }
+
+            return underlyingType;
+        }
+
         /// <summary>
         /// Gets the Open API description from the given <see cref="Type"/>.
         /// </summary>

src/Aliencube.AzureFunctions.Extensions.OpenApi.Core/Visitors/DictionaryObjectTypeVisitor.cs

@@ -47,7 +47,7 @@ public override void Visit(IAcceptor acceptor, KeyValuePair<string, Type> type,
             }
 
             // Gets the schema for the underlying type.
-            var underlyingType = type.Value.GetGenericArguments()[1];
+            var underlyingType = type.Value.GetUnderlyingType();
             var types = new Dictionary<string, Type>()
             {
                 { underlyingType.GetOpenApiTypeName(namingStrategy), underlyingType }

src/Aliencube.AzureFunctions.Extensions.OpenApi.Core/Visitors/ListObjectTypeVisitor.cs

@@ -47,7 +47,7 @@ public override void Visit(IAcceptor acceptor, KeyValuePair<string, Type> type,
             }
 
             // Gets the schema for the underlying type.
-            var underlyingType = type.Value.GetElementType() ?? type.Value.GetGenericArguments()[0];
+            var underlyingType = type.Value.GetUnderlyingType();
             var types = new Dictionary<string, Type>()
             {
                 { underlyingType.GetOpenApiTypeName(namingStrategy), underlyingType }

src/Aliencube.AzureFunctions.Extensions.OpenApi.Core/Visitors/NullableObjectTypeVisitor.cs

@@ -42,8 +42,7 @@ public override void Visit(IAcceptor acceptor, KeyValuePair<string, Type> type,
             }
 
             // Gets the schema for the underlying type.
-            type.Value.IsOpenApiNullable(out var underlyingType);
-
+            var underlyingType = type.Value.GetUnderlyingType();
             var types = new Dictionary<string, Type>()
             {
                 { type.Key, underlyingType }

test/Aliencube.AzureFunctions.Extensions.OpenApi.Core.Tests/Extensions/TypeExtensionsTests.cs

@@ -1,6 +1,8 @@
+using System;
 using System.Collections.Generic;
 
 using Aliencube.AzureFunctions.Extensions.OpenApi.Core.Extensions;
+using Aliencube.AzureFunctions.Extensions.OpenApi.Core.Tests.Fakes;
 
 using FluentAssertions;
 
@@ -57,5 +59,71 @@ public void Given_CamelCaseNamingStrategy_When_GetOpenApiTypeName_Invoked_Then_I
 
             result.Should().Be("int32");
         }
+
+        [DataTestMethod]
+        [DataRow(typeof(int))]
+        [DataRow(typeof(string))]
+        [DataRow(typeof(FakeModel))]
+        public void Given_NonGenericType_When_GetUnderlyingType_Invoked_Then_It_Should_Return_Null(Type type)
+        {
+            var result = TypeExtensions.GetUnderlyingType(type);
+
+            result.Should().BeNull();
+        }
+
+        [DataTestMethod]
+        [DataRow(typeof(int?), typeof(int))]
+        [DataRow(typeof(bool?), typeof(bool))]
+        [DataRow(typeof(DateTime?), typeof(DateTime))]
+        public void Given_NullableType_When_GetUnderlyingType_Invoked_Then_It_Should_Return_Result(Type type, Type expected)
+        {
+            var result = TypeExtensions.GetUnderlyingType(type);
+
+            result.Should().Be(expected);
+        }
+
+        [DataTestMethod]
+        [DataRow(typeof(List<int>), typeof(int))]
+        [DataRow(typeof(List<bool>), typeof(bool))]
+        [DataRow(typeof(List<FakeModel>), typeof(FakeModel))]
+        public void Given_ListType_When_GetUnderlyingType_Invoked_Then_It_Should_Return_Result(Type type, Type expected)
+        {
+            var result = TypeExtensions.GetUnderlyingType(type);
+
+            result.Should().Be(expected);
+        }
+
+        [DataTestMethod]
+        [DataRow(typeof(List<int?>), typeof(int))]
+        [DataRow(typeof(List<bool?>), typeof(bool))]
+        [DataRow(typeof(List<DateTime?>), typeof(DateTime))]
+        public void Given_NullableListType_When_GetUnderlyingType_Invoked_Then_It_Should_Return_Result(Type type, Type expected)
+        {
+            var result = TypeExtensions.GetUnderlyingType(type);
+
+            result.Should().Be(expected);
+        }
+
+        [DataTestMethod]
+        [DataRow(typeof(Dictionary<string, int>), typeof(int))]
+        [DataRow(typeof(Dictionary<string, bool>), typeof(bool))]
+        [DataRow(typeof(Dictionary<string, FakeModel>), typeof(FakeModel))]
+        public void Given_DictionaryType_When_GetUnderlyingType_Invoked_Then_It_Should_Return_Result(Type type, Type expected)
+        {
+            var result = TypeExtensions.GetUnderlyingType(type);
+
+            result.Should().Be(expected);
+        }
+
+        [DataTestMethod]
+        [DataRow(typeof(Dictionary<string, int?>), typeof(int))]
+        [DataRow(typeof(Dictionary<string, bool?>), typeof(bool))]
+        [DataRow(typeof(Dictionary<string, DateTime?>), typeof(DateTime))]
+        public void Given_NullableDictionaryType_When_GetUnderlyingType_Invoked_Then_It_Should_Return_Result(Type type, Type expected)
+        {
+            var result = TypeExtensions.GetUnderlyingType(type);
+
+            result.Should().Be(expected);
+        }
     }
 }