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ke_junjie

2025-06-04 101c57ec4c28bc3c36e49c50a926e9e7c0dd0247

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using IWareDataAccess.Helper;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
 
namespace IWareDataAccess.Helper
{
    public static class PredicateBuilder
    {
        private const String str_Start = "Start";
        private const String str_End = "End";
 
        public static Expression<Func<T, bool>> True<T>()
        {
            return f => true;
        }
 
        public static Expression<Func<T, bool>> False<T>()
        {
            return f => false;
        }
 
        public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1,
                                                            Expression<Func<T, bool>> expr2)
        {
            var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
            return Expression.Lambda<Func<T, bool>>
                  (Expression.OrElse(expr1.Body, invokedExpr), expr1.Parameters);
        }
 
        public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expr1,
                                                             Expression<Func<T, bool>> expr2)
        {
            var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
            return Expression.Lambda<Func<T, bool>>
                  (Expression.AndAlso(expr1.Body, invokedExpr), expr1.Parameters);
 
 
        }
 
 
        /// <summary>
        /// 获取筛选条件的查询表达式
        /// </summary>
        /// <typeparam name="T">查询对象</typeparam>
        /// <typeparam name="T2">返回对象</typeparam>
        /// <param name="t"></param>
        /// <returns></returns>
        public static Expression<Func<T2, bool>> GetFilterExpression<T, T2>(T t)
        {
            var f = PredicateBuilder.True<T2>();
            //便利所有属性
            Type type = t.GetType();
            foreach (var i in type.GetProperties())
            {
                var _noDbFilterAttribute = AttributeHelper.GetNoDbFilterAttributeByPro(i);
                if (_noDbFilterAttribute.Length > 0)
                {
                    continue;
                }
                object v = Helper.GetFieldValueByName(t, i.Name);
                if (i.PropertyType == typeof(String))
                {
                    string value;
                    if (v != null)
                    {
                        value = v.ToString();
                        f = f.And(x => Helper.GetFieldValueByName(x, i.Name) != null ? Helper.GetFieldValueByName(x, i.Name).ToString() == value : false);
                    }
                }
                else if (i.PropertyType == typeof(DateTime?))
                {
                    if (v != null)
                    {
                        DateTime value = DateTime.Parse(v.ToString());
 
                        if (i.Name.IndexOf(str_Start) > -1)
                        {
                            var name = GetTimeName(i.Name, str_Start);
                            //f = f.And(x => x.updateTime > value);
                            f = f.And(x => Helper.GetFieldValueByName(x, name) != null ? Convert.ToDateTime(Helper.GetFieldValueByName(x, name)) > value : false);
                        }
                        if (i.Name.IndexOf(str_End) > -1)
                        {
                            var name = GetTimeName(i.Name, str_End);
                            //f = f.And(x => x.updateTime < value);
                            f = f.And(x => Helper.GetFieldValueByName(x, name) != null ? Convert.ToDateTime(Helper.GetFieldValueByName(x, name)) < value : false);
                        }
                    }
                }
                else
                {
                    if (v != null)
                    {
                        f = f.And(x => Object.Equals(Helper.GetFieldValueByName(x, i.Name), v));
                    }
                }
            }
            return f;
        }
 
 
 
        /// <summary>
        /// 解析前台查询传过来的属性名
        /// </summary>
        /// <param name="inputName"></param>
        /// <returns></returns>
        private static string GetTimeName(string inputName, string indexName)
        {
            //updateTimeStart updateTimeEnd
            //doTimeStart doTimeEnd createTimeEnd
            //createTimeStart 
 
            int index = 0;
 
            index = inputName.IndexOf(indexName);
            if (index > -1)
            {
                return inputName.Substring(0, index);
            }
            return inputName;
        }
    }
}