using System;
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using System.Collections.Generic;
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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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using WIDESEA_Core.Enums;
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namespace WIDESEA_Core.Extensions
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{
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public static class LambdaExtensions
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{
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/// <summary>
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/// 分页查询
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="queryable"></param>
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/// <param name="page"></param>
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/// <param name="size"></param>
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/// <returns></returns>
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public static IQueryable<T> TakePage<T>(this IQueryable<T> queryable, int page, int size = 15)
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{
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return queryable.TakeOrderByPage<T>(page, size);
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}
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/// <summary>
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/// 分页查询
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="queryable"></param>
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/// <param name="page"></param>
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/// <param name="size"></param>
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/// <param name="orderBy"></param>
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/// <returns></returns>
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public static IQueryable<T> TakeOrderByPage<T>(this IQueryable<T> queryable, int page, int size = 15, Expression<Func<T, Dictionary<object, QueryOrderBy>>> orderBy = null)
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{
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if (page <= 0)
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{
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page = 1;
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}
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return queryable.GetIQueryableOrderBy(orderBy.GetExpressionToDic())
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.Skip((page - 1) * size)
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.Take(size);
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}
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/// <summary>
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/// 创建lambda表达式：p=>true
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <returns></returns>
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public static Expression<Func<T, bool>> True<T>()
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{
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return p => true;
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}
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/// <summary>
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/// 创建lambda表达式：p=>false
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <returns></returns>
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public static Expression<Func<T, bool>> False<T>()
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{
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return p => false;
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}
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public static ParameterExpression GetExpressionParameter(this Type type)
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{
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return Expression.Parameter(type, "p");
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}
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/// <summary>
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/// 创建lambda表达式：p=>p.propertyName
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <typeparam name="TKey"></typeparam>
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/// <param name="sort"></param>
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/// <returns></returns>
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public static Expression<Func<T, TKey>> GetExpression<T, TKey>(this string propertyName)
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{
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return propertyName.GetExpression<T, TKey>(typeof(T).GetExpressionParameter());
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}
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/// <summary>
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/// 创建委托有返回值的表达式：p=>p.propertyName
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <typeparam name="TKey"></typeparam>
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/// <param name="sort"></param>
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/// <returns></returns>
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public static Func<T, TKey> GetFun<T, TKey>(this string propertyName)
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{
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return propertyName.GetExpression<T, TKey>(typeof(T).GetExpressionParameter()).Compile();
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}
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/// <summary>
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/// 创建lambda表达式：p=>false
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/// 在已知TKey字段类型时,如动态排序OrderBy(x=>x.ID)会用到此功能,返回的就是x=>x.ID
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/// Expression<Func<Out_Scheduling, DateTime>> expression = x => x.CreateDate;指定了类型
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <returns></returns>
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public static Expression<Func<T, TKey>> GetExpression<T, TKey>(this string propertyName, ParameterExpression parameter)
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{
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if (typeof(TKey).Name == "Object")
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return Expression.Lambda<Func<T, TKey>>(Expression.Convert(Expression.Property(parameter, propertyName), typeof(object)), parameter);
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return Expression.Lambda<Func<T, TKey>>(Expression.Property(parameter, propertyName), parameter);
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}
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/// <summary>
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/// 创建lambda表达式：p=>false
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/// object不能确认字段类型(datetime,int,string),如动态排序OrderBy(x=>x.ID)会用到此功能,返回的就是x=>x.ID
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/// Expression<Func<Out_Scheduling, object>> expression = x => x.CreateDate;任意类型的字段
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <returns></returns>
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public static Expression<Func<T, object>> GetExpression<T>(this string propertyName)
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{
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return propertyName.GetExpression<T, object>(typeof(T).GetExpressionParameter());
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}
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public static Expression<Func<T, object>> GetExpression<T>(this string propertyName, ParameterExpression parameter)
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{
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return Expression.Lambda<Func<T, object>>(Expression.Convert(Expression.Property(parameter, propertyName), typeof(object)), parameter);
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}
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/// <summary>
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///
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="propertyName">字段名</param>
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/// <param name="propertyValue">表达式的值</param>
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/// <param name="expressionType">创建表达式的类型,如:p=>p.propertyName != propertyValue
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/// p=>p.propertyName.Contains(propertyValue)</param>
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/// <returns></returns>
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public static Expression<Func<T, bool>> CreateExpression<T>(this string propertyName, object propertyValue, LinqExpressionType expressionType)
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{
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return propertyName.CreateExpression<T>(propertyValue, null, expressionType);
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}
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/// <summary>
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///
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="propertyName">字段名</param>
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/// <param name="propertyValue">表达式的值</param>
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/// <param name="expressionType">创建表达式的类型,如:p=>p.propertyName != propertyValue
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/// p=>p.propertyName.Contains(propertyValue)</param>
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/// <returns></returns>
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private static Expression<Func<T, bool>> CreateExpression<T>(
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this string propertyName,
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object propertyValue,
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ParameterExpression parameter,
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LinqExpressionType expressionType)
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{
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Type proType = typeof(T).GetProperty(propertyName).PropertyType;
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//创建节点变量如p=>的节点p
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// parameter ??= Expression.Parameter(typeof(T), "p");//创建参数p
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parameter = parameter ?? Expression.Parameter(typeof(T), "p");
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//创建节点的属性p=>p.name 属性name
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MemberExpression memberProperty = Expression.PropertyOrField(parameter, propertyName);
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if (expressionType == LinqExpressionType.In)
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{
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if (!(propertyValue is System.Collections.IList list) || list.Count == 0) throw new Exception("属性值类型不正确");
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bool isStringValue = true;
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List<object> objList = new List<object>();
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if (proType.ToString() != "System.String")
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{
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isStringValue = false;
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foreach (var value in list)
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{
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objList.Add(value.ToString().ChangeType(proType));
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}
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list = objList;
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}
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if (isStringValue)
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{
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//string 类型的字段，如果值带有'单引号,EF会默认变成''两个单引号
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MethodInfo method = typeof(System.Collections.IList).GetMethod("Contains");
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//创建集合常量并设置为常量的值
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ConstantExpression constantCollection = Expression.Constant(list);
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//创建一个表示调用带参数的方法的：new string[]{"1","a"}.Contains("a");
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MethodCallExpression methodCall = Expression.Call(constantCollection, method, memberProperty);
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return Expression.Lambda<Func<T, bool>>(methodCall, parameter);
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}
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//非string字段，按上面方式处理报异常Null TypeMapping in Sql Tree
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BinaryExpression body = null;
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foreach (var value in list)
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{
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ConstantExpression constantExpression = Expression.Constant(value);
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UnaryExpression unaryExpression = Expression.Convert(memberProperty, constantExpression.Type);
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body = body == null
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? Expression.Equal(unaryExpression, constantExpression)
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: Expression.OrElse(body, Expression.Equal(unaryExpression, constantExpression));
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}
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return Expression.Lambda<Func<T, bool>>(body, parameter);
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}
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// object value = propertyValue;
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ConstantExpression constant = proType.ToString() == "System.String"
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? Expression.Constant(propertyValue) : Expression.Constant(propertyValue.ToString().ChangeType(proType));
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UnaryExpression member = Expression.Convert(memberProperty, constant.Type);
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Expression<Func<T, bool>> expression;
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switch (expressionType)
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{
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//p=>p.propertyName == propertyValue
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case LinqExpressionType.Equal:
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expression = Expression.Lambda<Func<T, bool>>(Expression.Equal(member, constant), parameter);
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break;
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//p=>p.propertyName != propertyValue
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case LinqExpressionType.NotEqual:
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expression = Expression.Lambda<Func<T, bool>>(Expression.NotEqual(member, constant), parameter);
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break;
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// p => p.propertyName > propertyValue
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case LinqExpressionType.GreaterThan:
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expression = Expression.Lambda<Func<T, bool>>(Expression.GreaterThan(member, constant), parameter);
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break;
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// p => p.propertyName < propertyValue
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case LinqExpressionType.LessThan:
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expression = Expression.Lambda<Func<T, bool>>(Expression.LessThan(member, constant), parameter);
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break;
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// p => p.propertyName >= propertyValue
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case LinqExpressionType.ThanOrEqual:
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expression = Expression.Lambda<Func<T, bool>>(Expression.GreaterThanOrEqual(member, constant), parameter);
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break;
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// p => p.propertyName <= propertyValue
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case LinqExpressionType.LessThanOrEqual:
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expression = Expression.Lambda<Func<T, bool>>(Expression.LessThanOrEqual(member, constant), parameter);
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break;
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// p => p.propertyName.Contains(propertyValue)
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// p => !p.propertyName.Contains(propertyValue)
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case LinqExpressionType.Contains:
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case LinqExpressionType.NotContains:
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MethodInfo method = typeof(string).GetMethod("Contains", new[] { typeof(string) });
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constant = Expression.Constant(propertyValue, typeof(string));
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if (expressionType == LinqExpressionType.Contains)
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{
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expression = Expression.Lambda<Func<T, bool>>(Expression.Call(member, method, constant), parameter);
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}
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else
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{
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expression = Expression.Lambda<Func<T, bool>>(Expression.Not(Expression.Call(member, method, constant)), parameter);
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}
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break;
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default:
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// p => p.false
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expression = False<T>();
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break;
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}
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return expression;
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}
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/// <summary>
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/// 表达式转换成KeyValList(主要用于多字段排序，并且多个字段的排序规则不一样)
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/// 如有多个字段进行排序,参数格式为
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/// Expression<Func<Out_Scheduling, Dictionary<object, bool>>> orderBy = x => new Dictionary<object, bool>() {
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/// { x.ID, true },
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/// { x.DestWarehouseName, true }
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/// };
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/// 返回的是new Dictionary<object, bool>(){{}}key为排序字段，bool为升降序
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="expression"></param>
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/// <returns></returns>
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public static IEnumerable<KeyValuePair<string, QueryOrderBy>> GetExpressionToPair<T>(this Expression<Func<T, Dictionary<object, QueryOrderBy>>> expression)
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{
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foreach (var exp in ((ListInitExpression)expression.Body).Initializers)
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{
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yield return new KeyValuePair<string, QueryOrderBy>(
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exp.Arguments[0] is MemberExpression ?
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(exp.Arguments[0] as MemberExpression).Member.Name.ToString()
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: ((exp.Arguments[0] as UnaryExpression).Operand as MemberExpression).Member.Name,
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(QueryOrderBy)((exp.Arguments[1] as ConstantExpression).Value));
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}
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}
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/// <summary>
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/// 表达式转换成KeyValList(主要用于多字段排序，并且多个字段的排序规则不一样)
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/// 如有多个字段进行排序,参数格式为
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/// Expression<Func<Out_Scheduling, Dictionary<object, QueryOrderBy>>> orderBy = x => new Dictionary<object, QueryOrderBy>() {
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/// { x.ID, QueryOrderBy.Desc },
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/// { x.DestWarehouseName, QueryOrderBy.Asc }
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/// };
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/// 返回的是new Dictionary<object, QueryOrderBy>(){{}}key为排序字段，QueryOrderBy为排序方式
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="expression"></param>
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/// <returns></returns>
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public static Dictionary<string, QueryOrderBy> GetExpressionToDic<T>(this Expression<Func<T, Dictionary<object, QueryOrderBy>>> expression)
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{
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return expression.GetExpressionToPair().Reverse().ToList().ToDictionary(x => x.Key, x => x.Value);
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}
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/// <summary>
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/// 解析多字段排序
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/// </summary>
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/// <typeparam name="TEntity"></typeparam>
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/// <param name="queryable"></param>
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/// <param name="orderBySelector">string=排序的字段,bool=true降序/false升序</param>
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/// <returns></returns>
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public static IQueryable<TEntity> GetIQueryableOrderBy<TEntity>(this IQueryable<TEntity> queryable, Dictionary<string, QueryOrderBy> orderBySelector)
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{
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string[] orderByKeys = orderBySelector.Select(x => x.Key).ToArray();
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if (orderByKeys == null || orderByKeys.Length == 0) return queryable;
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IOrderedQueryable<TEntity> queryableOrderBy = null;
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// string orderByKey = orderByKeys[^1];
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string orderByKey = orderByKeys[orderByKeys.Length-1];
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queryableOrderBy = orderBySelector[orderByKey] == QueryOrderBy.Desc
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? queryableOrderBy = queryable.OrderByDescending(orderByKey.GetExpression<TEntity>())
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: queryable.OrderBy(orderByKey.GetExpression<TEntity>());
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for (int i = orderByKeys.Length - 2; i >= 0; i--)
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{
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queryableOrderBy = orderBySelector[orderByKeys[i]] == QueryOrderBy.Desc
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? queryableOrderBy.ThenByDescending(orderByKeys[i].GetExpression<TEntity>())
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: queryableOrderBy.ThenBy(orderByKeys[i].GetExpression<TEntity>());
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}
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return queryableOrderBy;
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}
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/// <summary>
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/// 获取对象表达式指定属性的值
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/// 如获取:Out_Scheduling对象的ID或基他字段
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/// </summary>
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/// <typeparam name="TEntity"></typeparam>
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/// <param name="expression">格式 Expression<Func<Out_Scheduling, object>>sch=x=>new {x.v1,x.v2} or x=>x.v1 解析里面的值返回为数组</param>
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/// <returns></returns>
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public static string[] GetExpressionToArray<TEntity>(this Expression<Func<TEntity, object>> expression)
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{
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string[] propertyNames = null;
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if (expression.Body is MemberExpression)
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{
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propertyNames = new string[] { ((MemberExpression)expression.Body).Member.Name };
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}
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else
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{
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propertyNames = expression.GetExpressionProperty().Distinct().ToArray();
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}
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return propertyNames;
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}
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/// <summary>
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/// 与下面and生成方式有所不同，如果直接用表达式1.2进行合并产会提示数据源不同的异常，只能使用下面的的and合并
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/// 此种合并是在使用的同一个数据源(变量),生成的sql语句同样有性能问题(本身可以索引扫描的,生成的sql语句的case when变成索引查找)
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/// <summary>
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/// 通过字段动态生成where and /or表达
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/// 如:有多个where条件，当条件成立时where 1=1 and/or 2=2,依次往后拼接
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///
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="listParas">ExpressionParameters
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/// 1、Field生成的字段
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/// 2、ExpressionType 表达式类型大于、小于、于大=、小于=、contains
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/// 3、Value表达式的值
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/// </param>
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/// <returns></returns>
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public static Expression<Func<T, bool>> And<T>(List<ExpressionParameters> listExpress)
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{
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return listExpress.Compose<T>(Expression.And);
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}
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/// <summary>
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/// 同上面and用法相同
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="listExpress"></param>
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/// <returns></returns>
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public static Expression<Func<T, bool>> Or<T>(this List<ExpressionParameters> listExpress)
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{
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return listExpress.Compose<T>(Expression.Or);
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}
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private static Expression<Func<T, bool>> Compose<T>(this List<ExpressionParameters> listExpress, Func<Expression, Expression, Expression> merge)
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{
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ParameterExpression parameter = Expression.Parameter(typeof(T), "p");
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Expression<Func<T, bool>> expression = null;
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foreach (ExpressionParameters exp in listExpress)
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{
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if (expression == null)
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{
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expression = exp.Field.GetExpression<T, bool>(parameter);
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}
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else
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{
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expression = expression.Compose(exp.Field.GetExpression<T, bool>(parameter), merge);
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}
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}
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return expression;
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}
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/// <summary>
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/// https://blogs.msdn.microsoft.com/meek/2008/05/02/linq-to-entities-combining-predicates/
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/// 表达式合并(合并生产的sql语句有性能问题)
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/// 合并两个where条件，如：多个查询条件时，判断条件成立才where
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="first"></param>
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/// <param name="second"></param>
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/// <returns></returns>
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public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
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{
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return first.Compose(second, Expression.And);
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}
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public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
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{
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return first.Compose(second, Expression.Or);
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}
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public static Expression<T> Compose<T>(this Expression<T> first, Expression<T> second, Func<Expression, Expression, Expression> merge)
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{
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// build parameter map (from parameters of second to parameters of first)
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var map = first.Parameters.Select((f, i) => new { f, s = second.Parameters[i] }).ToDictionary(p => p.s, p => p.f);
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// replace parameters in the second lambda expression with parameters from the first
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var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);
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// apply composition of lambda expression bodies to parameters from the first expression
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return Expression.Lambda<T>(merge(first.Body, secondBody), first.Parameters);
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}
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public static IQueryable<Result> GetQueryableSelect<Source, Result>(this IQueryable<Source> queryable)
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{
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Expression<Func<Source, Result>> expression = CreateMemberInitExpression<Source, Result>();
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return queryable.Select(expression);
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}
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/// <summary>
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/// 动态创建表达式Expression<Func<Animal, User>> expression = CreateMemberInitExpression<Animal, User>();
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///结果为Expression<Func<Animal, User>> expression1 = x => new User() { Age = x.Age, Species = x.Species };
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///参照文档https://docs.microsoft.com/zh-cn/dotnet/api/system.linq.expressions.memberinitexpression?redirectedfrom=MSDN&view=netframework-4.8
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/// </summary>
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/// <typeparam name="Source"></typeparam>
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/// <typeparam name="Result"></typeparam>
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/// <returns></returns>
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public static Expression<Func<Source, Result>> CreateMemberInitExpression<Source, Result>(Type resultType = null)
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{
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resultType = resultType ?? typeof(Result);
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ParameterExpression left = Expression.Parameter(typeof(Source), "p");
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NewExpression newExpression = Expression.New(resultType);
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PropertyInfo[] propertyInfos = resultType.GetProperties();
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List<MemberBinding> memberBindings = new List<MemberBinding>();
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foreach (PropertyInfo propertyInfo in propertyInfos)
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{
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MemberExpression member = Expression.Property(left, propertyInfo.Name);
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MemberBinding speciesMemberBinding = Expression.Bind(resultType.GetMember(propertyInfo.Name)[0], member);
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memberBindings.Add(speciesMemberBinding);
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}
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MemberInitExpression memberInitExpression = Expression.MemberInit(newExpression, memberBindings);
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Expression<Func<Source, Result>> expression = Expression.Lambda<Func<Source, Result>>(memberInitExpression, new ParameterExpression[] { left });
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return expression;
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}
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public static Expression<Func<Source, object>> CreateMemberInitExpression<Source>(Type resultType)
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{
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return CreateMemberInitExpression<Source, object>(resultType);
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}
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/// <summary>
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/// 属性判断待完
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/// </summary>
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/// <param name="type"></param>
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/// <returns></returns>
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public static IEnumerable<PropertyInfo> GetGenericProperties(this Type type)
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{
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return type.GetProperties().GetGenericProperties();
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}
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/// <summary>
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/// 属性判断待完
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/// </summary>
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/// <param name="properties"></param>
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/// <returns></returns>
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public static IEnumerable<PropertyInfo> GetGenericProperties(this IEnumerable<PropertyInfo> properties)
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{
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return properties.Where(x => !x.PropertyType.IsGenericType && x.PropertyType.GetInterface("IList") == null || x.PropertyType.GetInterface("IEnumerable", false) == null);
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}
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}
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public class ExpressionParameters
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{
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public string Field { get; set; }
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public LinqExpressionType ExpressionType { get; set; }
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public object Value { get; set; }
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// public
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}
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public class ParameterRebinder : ExpressionVisitor
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{
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private readonly Dictionary<ParameterExpression, ParameterExpression> map;
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public ParameterRebinder(Dictionary<ParameterExpression, ParameterExpression> map)
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{
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this.map = map ?? new Dictionary<ParameterExpression, ParameterExpression>();
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}
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public static Expression ReplaceParameters(Dictionary<ParameterExpression, ParameterExpression> map, Expression exp)
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{
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return new ParameterRebinder(map).Visit(exp);
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}
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protected override Expression VisitParameter(ParameterExpression p)
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{
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ParameterExpression replacement;
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if (map.TryGetValue(p, out replacement))
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{
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p = replacement;
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}
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return base.VisitParameter(p);
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}
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}
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}
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