C# 反射 表达式树 模糊搜索

反射实体T，非datetime字段反射获取表达式树

  public static Expression<Func<T, bool>> GetSearchExpression<T>(string SearchString)
 
        {
 
            Expression<Func<T, bool>> filter = null;
 
            if (string.IsNullOrEmpty(SearchString)) return null;
 
            var left = Expression.Parameter(typeof(T), "m");
 
            Expression expression = Expression.Constant(false);
 
            T obj = default(T);
 
            var type = typeof(T);
 
            obj = (T)Activator.CreateInstance(type);
 
            var propertyInfos = type.GetProperties();
 
            foreach (var propertyInfo in propertyInfos)
 
            {
 
                if (propertyInfo.Name.ToLower() == "id" || propertyInfo.PropertyType == typeof(DateTime)) continue;
 
                Expression tostring = Expression.Call
 
         (
 
             Expression.Property(left, typeof(T).GetProperty(propertyInfo.Name).Name),
 
           typeof(object).GetMethod("ToString", new Type[] { })
 
         );
 
                Expression right = Expression.Call
 
                      (
 
                          tostring,
 
                        typeof(string).GetMethod("Contains", new Type[] { typeof(string) }),
 
                        Expression.Constant(SearchString)
 
                      );
 
                expression = Expression.Or(right, expression);
 
            }
 
            filter = Expression.Lambda<Func<T, bool>>(expression, new[] { left });
 
            return filter;
 
        }