Use TypeHelper in IQueryableExtensions.Filter

src/JsonApiDotNetCore/Extensions/IQueryableExtensions.cs

@@ -78,7 +78,7 @@ public static IQueryable<TSource> Filter<TSource>(this IQueryable<TSource> sourc
             {
                 // convert the incoming value to the target value type
                 // "1" -> 1
-                var convertedValue = Convert.ChangeType(filterQuery.PropertyValue, property.PropertyType);
+                var convertedValue = TypeHelper.ConvertType(filterQuery.PropertyValue, property.PropertyType);
                 // {model}
                 var parameter = Expression.Parameter(concreteType, "model");
                 // {model.Id}

src/JsonApiDotNetCoreExample/Migrations/20170330234539_AddGuidProperty.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+namespace JsonApiDotNetCoreExample.Migrations
+{
+    public partial class AddGuidProperty : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<Guid>(
+                name: "GuidProperty",
+                table: "TodoItems",
+                nullable: false,
+                defaultValue: new Guid("00000000-0000-0000-0000-000000000000"));
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "GuidProperty",
+                table: "TodoItems");
+        }
+    }
+}

src/JsonApiDotNetCoreExample/Migrations/AppDbContextModelSnapshot.cs

@@ -41,6 +41,8 @@ protected override void BuildModel(ModelBuilder modelBuilder)
 
                     b.Property<string>("Description");
 
+                    b.Property<Guid>("GuidProperty");
+
                     b.Property<long>("Ordinal");
 
                     b.Property<int?>("OwnerId");

src/JsonApiDotNetCoreExample/Models/TodoItem.cs

@@ -5,11 +5,19 @@ namespace JsonApiDotNetCoreExample.Models
 {
     public class TodoItem : Identifiable
     {
+        public TodoItem()
+        {
+            GuidProperty = Guid.NewGuid();
+        }
+
         [Attr("description")]
         public string Description { get; set; }
 
         [Attr("ordinal")]
         public long Ordinal { get; set; }
+
+        [Attr("guid-property")]
+        public Guid GuidProperty { get; set; }
 
         public int? OwnerId { get; set; }
         public int? AssigneeId { get; set; }

test/JsonApiDotNetCoreExampleTests/Acceptance/Spec/AttributeFilterTests.cs

@@ -0,0 +1,67 @@
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using DotNetCoreDocs;
+using DotNetCoreDocs.Models;
+using DotNetCoreDocs.Writers;
+using JsonApiDotNetCoreExample;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.TestHost;
+using Newtonsoft.Json;
+using Xunit;
+using JsonApiDotNetCore.Internal;
+using JsonApiDotNetCoreExample.Data;
+using Bogus;
+using JsonApiDotNetCoreExample.Models;
+using JsonApiDotNetCore.Serialization;
+using System.Linq;
+
+namespace JsonApiDotNetCoreExampleTests.Acceptance.Spec
+{
+    [Collection("WebHostCollection")]
+    public class AttributeFilterTests
+    {
+        private DocsFixture<Startup, JsonDocWriter> _fixture;
+        private Faker<TodoItem> _todoItemFaker;
+
+        public AttributeFilterTests(DocsFixture<Startup, JsonDocWriter> fixture)
+        {
+            _fixture = fixture;
+            _todoItemFaker = new Faker<TodoItem>()
+                .RuleFor(t => t.Description, f => f.Lorem.Sentence())
+                .RuleFor(t => t.Ordinal, f => f.Random.Number());
+        }
+
+        [Fact]
+        public async Task Can_Filter_On_Guid_Properties()
+        {
+            // arrange
+            var context = _fixture.GetService<AppDbContext>();
+            var todoItem = _todoItemFaker.Generate();
+            context.TodoItems.Add(todoItem);
+            await context.SaveChangesAsync();
+
+            var builder = new WebHostBuilder()
+                .UseStartup<Startup>();
+            var httpMethod = new HttpMethod("GET");
+            var route = $"/api/v1/todo-items?filter[guid-property]={todoItem.GuidProperty}";
+            var server = new TestServer(builder);
+            var client = server.CreateClient();
+            var request = new HttpRequestMessage(httpMethod, route);
+
+            // act
+            var response = await client.SendAsync(request);
+            var body = await response.Content.ReadAsStringAsync();
+            var deserializedBody = _fixture
+                .GetService<IJsonApiDeSerializer>()
+                .DeserializeList<TodoItem>(body);
+
+            var todoItemResponse = deserializedBody.Single();
+
+            // assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal(todoItem.Id, todoItemResponse.Id);
+            Assert.Equal(todoItem.GuidProperty, todoItemResponse.GuidProperty);
+        }
+    }
+}

test/JsonApiDotNetCoreExampleTests/Acceptance/Spec/FetchingRelationshipsTests.cs

@@ -1,24 +1,17 @@
-using System;
-using System.Collections.Generic;
 using System.Linq;
 using System.Net;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Bogus;
 using DotNetCoreDocs;
 using DotNetCoreDocs.Writers;
-using JsonApiDotNetCore.Models;
-using JsonApiDotNetCore.Serialization;
 using JsonApiDotNetCore.Services;
 using JsonApiDotNetCoreExample;
 using JsonApiDotNetCoreExample.Data;
 using JsonApiDotNetCoreExample.Models;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.TestHost;
-using Newtonsoft.Json;
 using Xunit;
-using Person = JsonApiDotNetCoreExample.Models.Person;
-
 namespace JsonApiDotNetCoreExampleTests.Acceptance.Spec
 {
     [Collection("WebHostCollection")]