我的目标是创建一个SortRecords
接受 anIEnumerable<T>
和 aPropertyInfo
作为参数的方法。这IEnumerable<T>
是一个记录列表。PropertyInfo
是 的属性T
。调用时,SortRecords
应Enumerable.SortBy<T, typeof Property>
使用 调用该方法x => x.Property
。注意这里Enumerable.SortBy
有两个通用参数。此外,反射不能在 lambda 表达式中使用,因为 (a) 它很慢并且 (b) 它不适用于实体框架。
我已经编写了一些代码,但我一直看到错误消息Operation could destabilize the runtime
。这是我的代码的样子
for (int i = 0; i < NumberOfSorts; i++)
{
string propertyName = PropertyNames[ColumnSortOrder[i]];
PropertyInfo property = typeof(T).GetProperties().Single(p => p.Name == propertyName);
Func<IEnumerable<T>, PropertyInfo, IEnumerable<T>> sortingFunction = GetFunctionToSortRecords<T>(filteredRecords, property);
sortedRecords = GetFunctionToSortRecords<T>(filteredRecords, property)(filteredRecords, property);
}
结束第一个代码片段
方法定义如下
delegate IEnumerable<T> GetFunctionToSortRecordsDelegate<T>(IEnumerable<T> records, PropertyInfo propertyToSortOn);
public static Func<IEnumerable<T>, PropertyInfo, IEnumerable<T>> GetFunctionToSortRecords<T>(IEnumerable<T> records, PropertyInfo propertyToSortOn)
{
Type propertyType = propertyToSortOn.GetType();
DynamicMethod method = new DynamicMethod("SortRecords", typeof(IEnumerable<T>), new Type[] { typeof(IEnumerable<T>), typeof(PropertyInfo) });
ILGenerator generator = method.GetILGenerator();
MethodInfo GetPropertyValue = propertyToSortOn.GetGetMethod();
MethodInfo GetDefaultKeySelectorForProperty = typeof(DataTablesSorting).GetMethod("GetDefaultKeySelectorForProperty")
.MakeGenericMethod(new Type[] {typeof(T), propertyToSortOn.PropertyType });
MethodInfo EnumerableOrderBy = typeof(Enumerable).GetMethods()
.Single(m => m.Name == "OrderBy" && m.GetParameters().Count()==3);
// Get the default key selector for the property passed in.
generator.Emit(OpCodes.Ldarg_1); // property
generator.Emit(OpCodes.Call, GetDefaultKeySelectorForProperty);
// Save the default key selector at location 0
generator.Emit(OpCodes.Stloc_0);
generator.Emit(OpCodes.Ldarg_0); // records
generator.Emit(OpCodes.Ldloc_0); // default key selector
generator.Emit(OpCodes.Call, EnumerableOrderBy);
generator.Emit(OpCodes.Ret);
return ((GetFunctionToSortRecordsDelegate<T>)(method.CreateDelegate(typeof(GetFunctionToSortRecordsDelegate<T>)))).Invoke;
}
delegate TKey GetDefaultKeySelectorForPropertyDelegate<T, TKey>(T t);
public static Func<T, TKey> GetDefaultKeySelectorForProperty<T, TKey>(PropertyInfo property)
{
DynamicMethod method = new DynamicMethod("GetKeySelector", typeof(TKey), new Type[] { typeof(T) });
ILGenerator generator = method.GetILGenerator();
MethodInfo GetPropertyValue = property.GetGetMethod();
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Callvirt, GetPropertyValue);
generator.Emit(OpCodes.Ret);
return ((GetDefaultKeySelectorForPropertyDelegate<T, TKey>)(method.CreateDelegate(typeof(GetDefaultKeySelectorForPropertyDelegate<T, TKey>)))).Invoke;
}
我认为这个问题可能是相关的:DynamicMethod with generic type parameters