88 lines
3.9 KiB
C#
88 lines
3.9 KiB
C#
/*******************************************************************************
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* Copyright © 2016 WaterCloud.Framework 版权所有
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* Author: WaterCloud
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* Description: WaterCloud快速开发平台
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* Website：
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*********************************************************************************/
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using System;
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using System.Data.SqlClient;
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using System.Linq;
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using System.Linq.Expressions;
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using System.Reflection;
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namespace WaterCloud.Code
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{
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public static partial class ExtLinq
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{
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public static IOrderedQueryable<TEntity> SortBy<TEntity>(this IQueryable<TEntity> query, Expression<Func<TEntity, dynamic>> sortPredicate)
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where TEntity : class, new()
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{
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return InvokeSortBy(query, sortPredicate, SortOrder.Ascending);
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}
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public static IOrderedQueryable<TEntity> SortByDescending<TEntity>(this IQueryable<TEntity> query, Expression<Func<TEntity, dynamic>> sortPredicate)
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where TEntity : class, new()
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{
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return InvokeSortBy(query, sortPredicate, SortOrder.Descending);
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}
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private static IOrderedQueryable<TEntity> InvokeSortBy<TEntity>(IQueryable<TEntity> query,
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Expression<Func<TEntity, dynamic>> sortPredicate, SortOrder sortOrder)
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where TEntity : class, new()
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{
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var param = sortPredicate.Parameters[0];
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string propertyName = null;
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Type propertyType = null;
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Expression bodyExpression = null;
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if (sortPredicate.Body is UnaryExpression)
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{
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var unaryExpression = sortPredicate.Body as UnaryExpression;
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bodyExpression = unaryExpression.Operand;
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}
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else if (sortPredicate.Body is MemberExpression)
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{
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bodyExpression = sortPredicate.Body;
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}
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else
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throw new ArgumentException(@"The body of the sort predicate expression should be
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either UnaryExpression or MemberExpression.", "sortPredicate");
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var memberExpression = (MemberExpression)bodyExpression;
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propertyName = memberExpression.Member.Name;
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if (memberExpression.Member.MemberType == MemberTypes.Property)
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{
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var propertyInfo = memberExpression.Member as PropertyInfo;
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if (propertyInfo != null) propertyType = propertyInfo.PropertyType;
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}
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else
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throw new InvalidOperationException(@"Cannot evaluate the type of property since the member expression
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represented by the sort predicate expression does not contain a PropertyInfo object.");
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var funcType = typeof(Func<,>).MakeGenericType(typeof(TEntity), propertyType);
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var convertedExpression = Expression.Lambda(funcType,
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Expression.Convert(Expression.Property(param, propertyName), propertyType), param);
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var sortingMethods = typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static);
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var sortingMethodName = GetSortingMethodName(sortOrder);
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var sortingMethod = sortingMethods.First(sm => sm.Name == sortingMethodName &&
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sm.GetParameters().Length == 2);
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return (IOrderedQueryable<TEntity>)sortingMethod
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.MakeGenericMethod(typeof(TEntity), propertyType)
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.Invoke(null, new object[] { query, convertedExpression });
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}
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private static string GetSortingMethodName(SortOrder sortOrder)
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{
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switch (sortOrder)
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{
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case SortOrder.Ascending:
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return "OrderBy";
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case SortOrder.Descending:
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return "OrderByDescending";
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default:
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throw new ArgumentException("Sort Order must be specified as either Ascending or Descending.",
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"sortOrder");
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}
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}
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}
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}
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