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标题: 双击列表中的外键字段宽度时发生的问题 [打印本页]

作者: 忽然白发 时间: 2013-9-2 16:57
标题: 双击列表中的外键字段宽度时发生的问题
在线统计中，双击用户名和中文名之间的宽度，会报错，提示没有为类型“AppBox.Online”定义实例属性“User.Name”
这种错误只有在有外键关联的字段中才会出现。

作者: luokaijin 时间: 2013-9-4 14:19
我也发现者问题，怎么解决呀？

作者: ☆☆αβ☆☆ 时间: 2013-9-9 15:51
public static IQueryable<T> SortBy<T>(this IQueryable<T> source, string sortExpression)
      {
         if (source == null)
         {
            throw new ArgumentNullException("source");
         }

         string sortDirection = String.Empty;
         string propertyName = String.Empty;

         sortExpression = sortExpression.Trim();
         int spaceIndex = sortExpression.Trim().IndexOf(" ");
         // int spaceIndex1 = sortExpression.Trim().IndexOf(".");
         if (spaceIndex < 0)
         {
            propertyName = sortExpression;
            sortDirection = "ASC";
         }
         else
         {
            propertyName = sortExpression.Substring(0, spaceIndex);
            sortDirection = sortExpression.Substring(spaceIndex + 1).Trim();
         }
         //有关联属性
         if (propertyName.IndexOf('.') > 0)
         {
            if (sortDirection =="ASC")
                  return source.OrderBy(propertyName);
            else
                  return source.OrderByDescending(propertyName);
         }

         if (String.IsNullOrEmpty(propertyName))
         {
            return source;
         }

         ParameterExpression parameter = Expression.Parameter(source.ElementType, String.Empty);
         MemberExpression property = Expression.Property(parameter, propertyName);
         LambdaExpression lambda = Expression.Lambda(property, parameter);

         string methodName = (sortDirection == "ASC") ? "OrderBy" : "OrderByDescending";

         Expression methodCallExpression = Expression.Call(typeof(Queryable), methodName,
                                             new Type[] { source.ElementType, property.Type },
                                             source.Expression, Expression.Quote(lambda));

         return source.Provider.CreateQuery<T>(methodCallExpression);

      }

      public enum EOrderType
      {
         OrderBy = 0,
         OrderByDescending = 1,
         ThenBy = 2,
         ThenByDescending = 3
      }
      /// <summary>
      /// 升序排序
      /// </summary>
      /// <typeparam name="T"></typeparam>
      /// <param name="source"></param>
      /// <param name="property"></param>
      /// <returns></returns>
      public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string property)
      {
         return ApplyOrder<T>(source, property, EOrderType.OrderBy);
      }

      /// <summary>
      /// 降序排序
      /// </summary>
      /// <typeparam name="T"></typeparam>
      /// <param name="source"></param>
      /// <param name="property"></param>
      /// <returns></returns>
      public static IOrderedQueryable<T> OrderByDescending<T>(this IQueryable<T> source, string property)
      {
         return ApplyOrder<T>(source, property, EOrderType.OrderByDescending);
      }
      /// <summary>
      /// 应用排序
      /// </summary>
      /// <typeparam name="T"></typeparam>
      /// <param name="source"></param>
      /// <param name="property"></param>
      /// <param name="methodName"></param>
      /// <returns></returns>
      public static IOrderedQueryable<T> ApplyOrder<T>(this IQueryable<T> source, string property, EOrderType orderType)
      {
         var methodName = orderType.ToString();

         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
            System.Reflection.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;
      }
      /// <summary>
      /// ThenBy
      /// </summary>
      /// <typeparam name="T"></typeparam>
      /// <param name="source"></param>
      /// <param name="property"></param>
      /// <returns></returns>
      public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string property)
      {
         return ApplyOrder<T>(source, property, EOrderType.ThenBy);
      }

      /// <summary>
      /// ThenByDescending
      /// </summary>
      /// <typeparam name="T"></typeparam>
      /// <param name="source"></param>
      /// <param name="property"></param>
      /// <returns></returns>
      public static IOrderedQueryable<T> ThenByDescending<T>(this IOrderedQueryable<T> source, string property)
      {
         return ApplyOrder<T>(source, property, EOrderType.ThenByDescending);
      }
      baidu，google很久终于搞定

作者: 忽然白发 时间: 2013-9-9 16:42
太好了，改成你说的那样。问题解决了。

作者: tarcyshu 时间: 2014-3-6 08:54
厉害！.....

作者: sanshi 时间: 2014-3-30 21:17

☆☆αβ☆☆ 发表于 2013-9-9 15:51
public static IQueryable SortBy(this IQueryable source, string sortExpression)
{
...

多谢，回头更新一下
恭喜你获得“代码贡献”勋章

作者: shouzhi2007 时间: 2014-4-2 17:31
这个还是不会改

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