本文實例講述了C# linq查詢之動態OrderBy用法。分享給大家供大家參考。具體分析如下：
groupList是原始數據集合，List<T>
sortOrder是排序類型，desc 或者asc
sortName是排序屬性名稱
1.使用反射。
private static object GetPropertyValue(object obj, string property){ System.Reflection.PropertyInfo propertyInfo = obj.GetType().GetProperty(property); return propertyInfo.GetValue(obj, null);} var resultList = sortOrder == "desc" ? groupList.OrderByDescending(p => GetPropertyValue(p, sortName)) : groupList.OrderBy(p => GetPropertyValue(p, sortName));//linq方式：//var resultList1 = from p in groupList orderby GetPropertyValue(p, m.SortName) select p;if (sortOrder == "desc") resultList1 = from p in groupList orderby GetPropertyValue(p, sortName) descending select p;2.調用AsQueryable()
將泛型 System.Collections.Generic.IEnumerable<T> 轉換為泛型 System.Linq.IQueryable<T>。
var groupQueryList = groupList.AsQueryable();//herevar tmpList = groupQueryList.OrderBy(sortName, sortOrder);
需要如下擴展方法：
public static IOrderedQueryable<T> OrderByDescending<T>(this IQueryable<T> source, string property){ return ApplyOrder<T>(source, property, "OrderByDescending");}public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string property){ return ApplyOrder<T>(source, property, "ThenBy");}public static IOrderedQueryable<T> ThenByDescending<T>(this IOrderedQueryable<T> source, string property){ return ApplyOrder<T>(source, property, "ThenByDescending");}static IOrderedQueryable<T> ApplyOrder<T>(IQueryable<T> source, string property, string methodName) { string[] props = property.Split('.'); Type type = typeof(T); ParameterExpression arg = Expression.Parameter(type, "x"); Expression expr = arg; foreach(string prop in props) { // use reflection (not ComponentModel) to mirror LINQ PropertyInfo pi = type.GetProperty(prop); expr = Expression.Property(expr, pi); type = pi.PropertyType; } Type delegateType = typeof(Func<,>).MakeGenericType(typeof(T), type); LambdaExpression lambda = Expression.Lambda(delegateType, expr, arg); object result = typeof(Queryable).GetMethods().Single( method => method.Name == methodName && method.IsGenericMethodDefinition && method.GetGenericArguments().Length == 2 && method.GetParameters().Length == 2) .MakeGenericMethod(typeof(T), type) .Invoke(null, new object[] {source, lambda}); return (IOrderedQueryable<T>)result;}希望本文所述對大家的C#程序設計有所幫助。
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