Fixed: De-duplicate field names in sparse fieldset; do not ignore case

Inlined TypeHelper.ConvertCollection

Author: Bart Koelman

src/JsonApiDotNetCore/Extensions/SystemCollectionExtensions.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace JsonApiDotNetCore.Extensions
+{
+    internal static class SystemCollectionExtensions
+    {
+        public static void AddRange<T>(this ICollection<T> source, IEnumerable<T> items)
+        {
+            if (source == null) throw new ArgumentNullException(nameof(source));
+            if (items == null) throw new ArgumentNullException(nameof(items));
+
+            foreach (var item in items)
+            {
+                source.Add(item);
+            }
+        }
+
+        public static void AddRange<T>(this IList source, IEnumerable<T> items)
+        {
+            if (source == null) throw new ArgumentNullException(nameof(source));
+            if (items == null) throw new ArgumentNullException(nameof(items));
+
+            foreach (var item in items)
+            {
+                source.Add(item);
+            }
+        }
+    }
+}

src/JsonApiDotNetCore/Extensions/TypeExtensions.cs

@@ -9,28 +9,6 @@ namespace JsonApiDotNetCore.Extensions
 {
     internal static class TypeExtensions
     {
-
-        /// <summary>
-        /// Extension to use the LINQ AddRange method on an IList
-        /// </summary>
-        public static void AddRange<T>(this IList list, IEnumerable<T> items)
-        {
-            if (list == null) throw new ArgumentNullException(nameof(list));
-            if (items == null) throw new ArgumentNullException(nameof(items));
-
-            if (list is List<T> genericList)
-            {
-                genericList.AddRange(items);
-            }
-            else
-            {
-                foreach (var item in items)
-                {
-                    list.Add(item);
-                }
-            }
-        }
-            
         /// <summary>
         /// Extension to use the LINQ cast method in a non-generic way:
         /// <code>
@@ -42,32 +20,13 @@ public static IEnumerable Cast(this IEnumerable source, Type type)
         {
             if (source == null) throw new ArgumentNullException(nameof(source));
             if (type == null) throw new ArgumentNullException(nameof(type));
-            return TypeHelper.ConvertCollection(source.Cast<object>(), type);
-        }
-
-        public static Type GetElementType(this IEnumerable enumerable)
-        {
-            var enumerableTypes = enumerable.GetType()
-                .GetInterfaces()
-                .Where(t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof(IEnumerable<>))
-                .ToList();
-
-            var numberOfEnumerableTypes = enumerableTypes.Count;
-
-            if (numberOfEnumerableTypes == 0)
-            {
-                throw new ArgumentException($"{nameof(enumerable)} of type {enumerable.GetType().FullName} does not implement a generic variant of {nameof(IEnumerable)}");
-            }
 
-            if (numberOfEnumerableTypes > 1)
+            var list = (IList)Activator.CreateInstance(typeof(List<>).MakeGenericType(type));
+            foreach (var item in source.Cast<object>())
             {
-                throw new ArgumentException($"{nameof(enumerable)} of type {enumerable.GetType().FullName} implements more than one generic variant of {nameof(IEnumerable)}:\n" +
-                    $"{string.Join("\n", enumerableTypes.Select(t => t.FullName))}");
+                list.Add(TypeHelper.ConvertType(item, type));
             }
-
-            var elementType = enumerableTypes[0].GenericTypeArguments[0];
-
-            return elementType;
+            return list;
         }
 
         /// <summary>

src/JsonApiDotNetCore/Internal/TypeHelper.cs

@@ -11,13 +11,6 @@ namespace JsonApiDotNetCore.Internal
 {
     internal static class TypeHelper
     {
-        public static IList ConvertCollection(IEnumerable<object> collection, Type targetType)
-        {
-            var list = Activator.CreateInstance(typeof(List<>).MakeGenericType(targetType)) as IList;
-            foreach (var item in collection)
-                list.Add(ConvertType(item, targetType));
-            return list;
-        }
         private static bool IsNullable(Type type)
         {
             return (!type.IsValueType || Nullable.GetUnderlyingType(type) != null);

src/JsonApiDotNetCore/Models/Annotation/AttrAttribute.cs

@@ -124,7 +124,6 @@ private PropertyInfo GetResourceProperty(object resource)
         /// <summary>
         /// Whether or not the provided exposed name is equivalent to the one defined in on the model
         /// </summary>
-        public bool Is(string publicRelationshipName)
-            => string.Equals(publicRelationshipName, PublicAttributeName, StringComparison.OrdinalIgnoreCase);
+        public bool Is(string publicRelationshipName) => publicRelationshipName == PublicAttributeName;
     }
 }

src/JsonApiDotNetCore/Models/Annotation/RelationshipAttribute.cs

@@ -77,10 +77,9 @@ public override int GetHashCode()
         }
 
         /// <summary>
-        /// Whether or not the provided exposed name is equivalent to the one defined in on the model
+        /// Whether or not the provided exposed name is equivalent to the one defined in the model
         /// </summary>
-        public virtual bool Is(string publicRelationshipName)
-            => string.Equals(publicRelationshipName, PublicRelationshipName, StringComparison.OrdinalIgnoreCase);
+        public virtual bool Is(string publicRelationshipName) => publicRelationshipName == PublicRelationshipName;
 
         /// <summary>
         /// The internal navigation property path to the related entity.

src/JsonApiDotNetCore/QueryParameterServices/SparseFieldsService.cs

@@ -2,6 +2,7 @@
 using System.Linq;
 using JsonApiDotNetCore.Controllers;
 using JsonApiDotNetCore.Exceptions;
+using JsonApiDotNetCore.Extensions;
 using JsonApiDotNetCore.Internal.Contracts;
 using JsonApiDotNetCore.Internal.Query;
 using JsonApiDotNetCore.Managers.Contracts;
@@ -58,8 +59,10 @@ public virtual void Parse(string parameterName, StringValues parameterValue)
             //           articles?fields[articles]=prop1,prop2  <-- this form in invalid UNLESS "articles" is actually a relationship on Article
             //           articles?fields[relationship]=prop1,prop2
             EnsureNoNestedResourceRoute(parameterName);
-            var fields = new List<string> { nameof(Identifiable.Id) };
-            fields.AddRange(((string)parameterValue).Split(QueryConstants.COMMA));
+
+            HashSet<string> fields = new HashSet<string>();
+            fields.Add(nameof(Identifiable.Id).ToLowerInvariant());
+            fields.AddRange(((string) parameterValue).Split(QueryConstants.COMMA));
 
             var keySplit = parameterName.Split(QueryConstants.OPEN_BRACKET, QueryConstants.CLOSE_BRACKET);
 

src/JsonApiDotNetCore/Serialization/Common/BaseDocumentParser.cs

@@ -234,7 +234,7 @@ private void SetHasManyRelationship(
                     relatedInstance.StringId = rio.Id;
                     return relatedInstance;
                 });
-                var convertedCollection = TypeHelper.ConvertCollection(relatedResources, attr.RightType);
+                var convertedCollection = relatedResources.Cast(attr.RightType);
                 attr.SetValue(entity, convertedCollection);
             }
 

test/UnitTests/QueryParameters/SparseFieldsServiceTests.cs

@@ -68,8 +68,8 @@ public void Parse_ValidSelection_CanParse()
 
             // Assert
             Assert.NotEmpty(result);
-            Assert.Equal(idAttribute, result.First());
-            Assert.Equal(attribute, result[1]);
+            Assert.Contains(idAttribute, result);
+            Assert.Contains(attribute, result);
         }
 
         [Fact]