Allow Filters on different sources to share the same name

Allows Posts and Comments to both use the IsNew filter with their own implementations.

Sieve/Extensions/MethodInfoExtended.cs

@@ -0,0 +1,147 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+using System.Text;
+
+namespace Sieve.Extensions
+{
+    // The default GetMethod doesn't allow for generic methods which means
+    // custom filters for different sources can't share the same name.
+    // https://stackoverflow.com/questions/4035719/getmethod-for-generic-method
+    public static partial class MethodInfoExtended
+    {
+        /// <summary>
+        /// Search for a method by name and parameter types.  
+        /// Unlike GetMethod(), does 'loose' matching on generic
+        /// parameter types, and searches base interfaces.
+        /// </summary>
+        /// <exception cref="AmbiguousMatchException"/>
+        public static MethodInfo GetMethodExt(this Type thisType,
+                                                string name,
+                                                params Type[] parameterTypes)
+        {
+            return GetMethodExt(thisType,
+                                name,
+                                BindingFlags.Instance
+                                | BindingFlags.Static
+                                | BindingFlags.Public
+                                | BindingFlags.NonPublic
+                                | BindingFlags.FlattenHierarchy,
+                                parameterTypes);
+        }
+
+        /// <summary>
+        /// Search for a method by name, parameter types, and binding flags.  
+        /// Unlike GetMethod(), does 'loose' matching on generic
+        /// parameter types, and searches base interfaces.
+        /// </summary>
+        /// <exception cref="AmbiguousMatchException"/>
+        public static MethodInfo GetMethodExt(this Type thisType,
+                                                string name,
+                                                BindingFlags bindingFlags,
+                                                params Type[] parameterTypes)
+        {
+            MethodInfo matchingMethod = null;
+
+            // Check all methods with the specified name, including in base classes
+            GetMethodExt(ref matchingMethod, thisType, name, bindingFlags, parameterTypes);
+
+            // If we're searching an interface, we have to manually search base interfaces
+            if (matchingMethod == null && thisType.IsInterface)
+            {
+                foreach (Type interfaceType in thisType.GetInterfaces())
+                    GetMethodExt(ref matchingMethod,
+                                 interfaceType,
+                                 name,
+                                 bindingFlags,
+                                 parameterTypes);
+            }
+
+            return matchingMethod;
+        }
+
+        private static void GetMethodExt(ref MethodInfo matchingMethod,
+                                            Type type,
+                                            string name,
+                                            BindingFlags bindingFlags,
+                                            params Type[] parameterTypes)
+        {
+            // Check all methods with the specified name, including in base classes
+            foreach (MethodInfo methodInfo in type.GetMember(name,
+                                                             MemberTypes.Method,
+                                                             bindingFlags))
+            {
+                // Check that the parameter counts and types match, 
+                // with 'loose' matching on generic parameters
+                ParameterInfo[] parameterInfos = methodInfo.GetParameters();
+                if (parameterInfos.Length == parameterTypes.Length)
+                {
+                    int i = 0;
+                    for (; i < parameterInfos.Length; ++i)
+                    {
+                        if (!parameterInfos[i].ParameterType
+                                              .IsSimilarType(parameterTypes[i]))
+                            break;
+                    }
+                    if (i == parameterInfos.Length)
+                    {
+                        if (matchingMethod == null)
+                            matchingMethod = methodInfo;
+                        else
+                            throw new AmbiguousMatchException(
+                                   "More than one matching method found!");
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Special type used to match any generic parameter type in GetMethodExt().
+        /// </summary>
+        public class T
+        { }
+
+        /// <summary>
+        /// Determines if the two types are either identical, or are both generic 
+        /// parameters or generic types with generic parameters in the same
+        ///  locations (generic parameters match any other generic paramter,
+        /// but NOT concrete types).
+        /// </summary>
+        private static bool IsSimilarType(this Type thisType, Type type)
+        {
+            // Ignore any 'ref' types
+            if (thisType.IsByRef)
+                thisType = thisType.GetElementType();
+            if (type.IsByRef)
+                type = type.GetElementType();
+
+            // Handle array types
+            if (thisType.IsArray && type.IsArray)
+                return thisType.GetElementType().IsSimilarType(type.GetElementType());
+
+            // If the types are identical, or they're both generic parameters 
+            // or the special 'T' type, treat as a match
+            if (thisType == type || ((thisType.IsGenericParameter || thisType == typeof(T))
+                                 && (type.IsGenericParameter || type == typeof(T))))
+                return true;
+
+            // Handle any generic arguments
+            if (thisType.IsGenericType && type.IsGenericType)
+            {
+                Type[] thisArguments = thisType.GetGenericArguments();
+                Type[] arguments = type.GetGenericArguments();
+                if (thisArguments.Length == arguments.Length)
+                {
+                    for (int i = 0; i < thisArguments.Length; ++i)
+                    {
+                        if (!thisArguments[i].IsSimilarType(arguments[i]))
+                            return false;
+                    }
+                    return true;
+                }
+            }
+
+            return false;
+        }
+    }
+}

Sieve/Services/SieveProcessor.cs

@@ -315,8 +315,9 @@ namespace Sieve.Services
         private IQueryable<TEntity> ApplyCustomMethod<TEntity>(IQueryable<TEntity> result, string name, object parent, object[] parameters, object[] optionalParameters = null)
         {
             var customMethod = parent?.GetType()
-                .GetMethod(name,
+                .GetMethodExt(name,
-                _options.Value.CaseSensitive ? BindingFlags.Default : BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance);
+                _options.Value.CaseSensitive ? BindingFlags.Default : BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance,
+                new Type[] { typeof(IQueryable<TEntity>), typeof(string), typeof(string) });
 
             if (customMethod != null)
             {
@@ -337,18 +338,25 @@ namespace Sieve.Services
                         throw;
                     }
                 }
-                catch (ArgumentException) // name matched with custom method for a different type
+            }
+            else
+            {
+                var incompatibleCustomMethod = parent?.GetType()
+                    .GetMethod(name,
+                    _options.Value.CaseSensitive ? BindingFlags.Default : BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance);
+
+                if (incompatibleCustomMethod != null)
                 {
                     var expected = typeof(IQueryable<TEntity>);
-                    var actual = customMethod.ReturnType;
+                    var actual = incompatibleCustomMethod.ReturnType;
                     throw new SieveIncompatibleMethodException(name, expected, actual,
                         $"{name} failed. Expected a custom method for type {expected} but only found for type {actual}");
                 }
-            }
                 else
                 {
                     throw new SieveMethodNotFoundException(name, $"{name} not found.");
                 }
+            }
 
             return result;
         }

SieveUnitTests/Entities/Comment.cs

@@ -1,9 +1,15 @@
-namespace SieveUnitTests.Entities
+using System;
+using Sieve.Attributes;
+
+namespace SieveUnitTests.Entities
 {
 	public class Comment
     {
         public int Id { get; set; }
 
+        [Sieve(CanFilter = true, CanSort = true)]
+        public DateTimeOffset DateCreated { get; set; } = DateTimeOffset.UtcNow;
+
         public string Text { get; set; }
     }
 }

SieveUnitTests/General.cs

@@ -15,6 +15,7 @@ namespace SieveUnitTests
     {
         private readonly SieveProcessor _processor;
         private readonly IQueryable<Post> _posts;
+        private readonly IQueryable<Comment> _comments;
 
         public General()
         {
@@ -52,6 +53,25 @@ namespace SieveUnitTests
                     CategoryId = 2,
                 },
             }.AsQueryable();
+
+            _comments = new List<Comment>
+            {
+                new Comment() {
+                    Id = 0,
+                    DateCreated = DateTimeOffset.UtcNow.AddDays(-20),
+                    Text = "This is an old comment."
+                },
+                new Comment() {
+                    Id = 1,
+                    DateCreated = DateTimeOffset.UtcNow.AddDays(-1),
+                    Text = "This is a fairly new comment."
+                },
+                new Comment() {
+                    Id = 2,
+                    DateCreated = DateTimeOffset.UtcNow,
+                    Text = "This is a brand new comment."
+                },
+            }.AsQueryable();
         }
 
         [TestMethod]
@@ -180,6 +200,30 @@ namespace SieveUnitTests
             Assert.IsTrue(result.Count() == 1);
         }
 
+        [TestMethod]
+        public void CustomFiltersOnDifferentSourcesCanShareName()
+        {
+            var postModel = new SieveModel()
+            {
+                Filters = "CategoryId==2,Isnew",
+            };
+
+            var postResult = _processor.Apply(postModel, _posts);
+
+            Assert.IsTrue(postResult.Any(p => p.Id == 3));
+            Assert.AreEqual(1, postResult.Count());
+
+            var commentModel = new SieveModel()
+            {
+                Filters = "Isnew",
+            };
+
+            var commentResult = _processor.Apply(commentModel, _comments);
+
+            Assert.IsTrue(commentResult.Any(c => c.Id == 2));
+            Assert.AreEqual(2, commentResult.Count());
+        }
+
         [TestMethod]
         public void MethodNotFoundExceptionWork()
         {

SieveUnitTests/Services/SieveCustomFilterMethods.cs

@@ -1,4 +1,5 @@
-using System.Linq;
+using System;
+using System.Linq;
 using Sieve.Services;
 using SieveUnitTests.Entities;
 
@@ -13,6 +14,13 @@ namespace SieveUnitTests.Services
             return result;
         }
 
+        public IQueryable<Comment> IsNew(IQueryable<Comment> source, string op, string value)
+        {
+            var result = source.Where(c => c.DateCreated > DateTimeOffset.UtcNow.AddDays(-2));
+
+            return result;
+        }
+
         public IQueryable<Comment> TestComment(IQueryable<Comment> source, string op, string value)
         {
             return source;