Linq-包含DateTime字段的动态查询

问题描述

我进行了如下搜索：

我通过以下代码创建查询：

StringBuilder query = new StringBuilder();

string OrderBy = null;
switch (sortOrder)
{
    case "orderCode_desc":
        OrderBy = " OrderCode desc";
        break;
    case "mobile":
        OrderBy = "Mobile";
        break;
    case "mobile_desc":
        OrderBy = "Mobile desc";
        break;
    case "date":
        OrderBy = "OrderDate";
        break;
    case "date_desc":
        OrderBy = "OrderDate desc";
        break;
    case "orderCode":
    default:
        OrderBy = "OrderCode";
        break;
}

if (filters.SelectedProducts.NotNullString())
{
    var SelectedProducts = filters.SelectedProducts.Split(',');
    query.Append("(");
    for (int i = 0; i < SelectedProducts.Length; i++)
    {
        query.AppendFormat("uag.oag.ordDet.ProductID == {0}",SelectedProducts[i]);
        if (i != SelectedProducts.Length - 1)
        {
            query.Append(" || ");
        }
    }
    query.Append(") && ");
}


if (filters.DateFrom != null && filters.Dateto != null)
{
    query.AppendFormat("(uag.oag._order.order.OrderDate >= {0} && uag.oag._order.order.OrderDate <= {1} )",filters.DateFrom.Date,filters.Dateto.Date);
}
if (filters.DateFrom != null && filters.Dateto == null)
{
    query.AppendFormat("( uag.oag._order.order.OrderDate >= {0} )",filters.DateFrom.Date);
}
if (filters.DateFrom == null && filters.Dateto != null)
{
    query.AppendFormat("( uag.oag._order.order.OrderDate <= {0} )",filters.Dateto.Date);
}

string _query = query.ToString();
_query = _query.EndsWith("&& ") ? _query.Remove(_query.Length - 3) : _query;

orders = db.orders
        .Join(db.order_statuses,order => order.OrderStatusID,OrderStatus => OrderStatus.OrderStatusID,(order,OrderStatus) => new { order,OrderStatus })
        .Join(db.order_details,_order => _order.order.OrderID,ordDet => ordDet.OrderID,(_order,ordDet) => new { _order,ordDet })
        .Join(db.agents_info,oag => oag._order.order.AgentID,ag => ag.AgentInfoID,(oag,ag) => new { oag,ag })
        .Join(db.users,uag => uag.ag.UserID,u => u.UserID,(uag,u) => new { uag,u })
        .AsQueryable()
        .Where(_query)
        .Select(m => new OrderList
        {
            OrderID = m.uag.oag._order.order.OrderID,OrderCode = m.uag.oag._order.order.OrderCode,OrderDate = m.uag.oag._order.order.OrderDate,OrderStatus = m.uag.oag._order.OrderStatus.OrderStatusTitle,TotalPrice = m.uag.oag._order.order.TotalPrice,Mobile = m.u.Mobile
        }).OrderBy(OrderBy).Skip(PageSize * (page - 1)).Take(PageSize).ToList();

我得到一个错误：

运算符'> ='与操作数类型'DateTime'和'Int32'不兼容

here是相同的问题，他的问题通过使用参数化查询得以解决。我使用了参数化查询，但问题仍未解决。 我该如何解决这个问题？

解决方法

对于documentation，您需要使用公共构造函数来创建DateTime对象，因此类似

query.AppendFormat("(uag.oag._order.order.OrderDate >= {0} && uag.oag._order.order.OrderDate <= {1})",filters.DateFrom.Date.ToString(@"Da\teTi\me(yyyy,M,d)"),filters.DateTo.Date.ToString(@"Da\teTi\me(yyyy,d)"));