将LINQ查询绑定到asp：DataList时出现明显不可比较的错误

I keep getting this error with my below LINQ statement, and I can't figure out why.

我在下面的LINQ语句中不断收到此错误,我无法弄清楚原因。

The text data type cannot be selected as DISTINCT because it is not comparable.

无法将文本数据类型选择为DISTINCT,因为它不具有可比性。

var reportLoad = from dash in
                 (from rl in QVuser.QlikViewPermissions
                  join d in QVuser.QlikViewDashboards on rl.DashboardId equals d.DashboardId
                   where rl.UserId == user && rl.Active == true
                   group rl by new { DashName = d.DashboardName, DashProdLink = d.ProductionLink, DashTestLink = d.TestLink } into g
                   select new { DashName = g.Key.DashName, DashProdLink = g.Key.DashProdLink, DashTestLink = g.Key.DashTestLink })
                       select new
                       {
                            DashName = dash.DashName,
                            DashLink = (whichServer.UseProductionServer ? dash.DashProdLink : dash.DashTestLink)
                       };

this.DataList1.DataSource = reportLoad;
this.DataList1.DataBind();

3 个解决方案

#1

The problem is in your group by clause.

问题出在你的group by子句中。

group rl by new { DashName = d.DashboardName, DashProdLink = d.ProductionLink, DashTestLink = d.TestLink } into g

The by part of group by is what determines when each group stops and the next group ends. Typically a by clause will be something simple like d.DashboardName which will make groups based on each dashboard.

group by的部分是决定每个组何时停止并且下一个组结束的原因。通常,by子句将像d.DashboardName一样简单,它将根据每个仪表板创建组。

group d by d.DashboardName into g

Alternatively if you really want to use a complex object as your group key then create a real object, not an anonymous one, and in your custom object implement IComparable<>.

或者,如果您确实想要使用复杂对象作为组密钥,则创建一个真实对象,而不是匿名对象,并在自定义对象中实现IComparable <>。

group rl by new DashContainer { DashName = d.DashboardName, DashProdLink = d.ProductionLink, DashTestLink = d.TestLink } into g

#2

I figured it out.

我想到了。

var reportLoad =    from d in QVuser.QlikViewDashboards
                    orderby d.DashboardName
                    select new
                    {
                    DashName = d.DashboardName,
                    DashLink =
                             from dd in QVuser.QlikViewDashboards
                              join p in QVuser.QlikViewPermissions on d.DashboardId equals p.DashboardId
                              where p.UserId == user && p.Active == true
                              group dd by dd.DashboardName into g
                              select (whichServer.UseProductionServer ? d.ProductionLink : d.TestLink)
                    };

#3

Maybe you want to try calling ToList() on reportLoad before binding, as in:

也许你想在绑定之前尝试在reportLoad上调用ToList(),如:

this.DataList1.DataSource = reportLoad.ToList();

If ToList errors, then its an issue in the LINQ query, otherwise, it could be an issue with the data list and how its accessing your data.

如果ToList错误,那么它在LINQ查询中是一个问题,否则,它可能是数据列表的问题以及它如何访问您的数据。

HTH.

#1