Question

我有一个Linq-to-SQL数据模型，其中包含Party类型，对Company和Individual进行了两次细分。我试图将两个转发器绑定到Linq-to-SQL查询，如下所示

    Dim oComp As IEnumerable(Of Company)
    Dim oInd As IEnumerable(Of Individual)

        oComp = From oP As Company In ERM.Parties _
                 Where TypeOf (oP) Is Company And _
                 oP.Name.StartsWith(sSearchString)

        oInd = From oP As Individual In ERM.Parties _
                Where TypeOf (oP) Is Individual And _
                (oP.FirstName.StartsWith(sSearchString) Or _
                oP.LastName.StartsWith(sSearchString))

        rptIndividuals.DataSource = oInd
        rptCompanies.DataSource = oComp

        rptCompanies.DataBind()
        rptIndividuals.DataBind()

当我按预期逐步执行代码oComp和oInd IEnumerable<Company>和IEnumerable<Individual>时，但在第一次DataBind调用时，我收到以下异常到达

System.MissingMethodException未被用户代码处理 Message =“类型上的构造函数”System.Data.Linq.Provider.DataBindingList 1[[DataModel.Party, DataModel, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]' not found." Source="mscorlib" StackTrace: at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) at System.Data.Linq.Provider.BindingList.Create[T](DataContext context, IEnumerable 1个序列） at System.Data.Linq.DataQuery 1.GetNewBindingList() at System.Data.Linq.DataQuery 1.System.ComponentModel.IListSource.GetList（）在System.Web.UI.DataSourceHelper.GetResolvedDataSource（Object dataSource，String dataMember）在System.Web.UI.WebControls.ReadOnlyDataSource.System.Web.UI.IDataSource.GetView（String viewName）在System.Web.UI.WebControls.Repeater.ConnectToDataSourceView（）在System.Web.UI.WebControls.Repeater.GetData（）在System.Web.UI.WebControls.Repeater.CreateControlHierarchy（Boolean useDataSource）在System.Web.UI.WebControls.Repeater.OnDataBinding（EventArgs e）在System.Web.UI.WebControls.Repeater.DataBind（） at parties.lbHiddenPostback_Click（Object sender，EventArgs e）在\ parties.aspx.vb中：第491行在System.Web.UI.WebControls.LinkButton.OnClick（EventArgs e）在System.Web.UI.WebControls.LinkButton.RaisePostBackEvent（String eventArgument）在System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent（String eventArgument）在System.Web.UI.Page.RaisePostBackEvent（IPostBackEventHandler sourceControl，String eventArgument）在System.Web.UI.Page.RaisePostBackEvent（NameValueCollection postData）在System.Web.UI.Page.ProcessRequestMain（Boolean includeStagesBeforeAsyncPoint，Boolean includeStagesAfterAsyncPoint） InnerException：

如果我然后按照以下方式选择所有内容，那么一切正常

    Dim oComp As IEnumerable(Of Party)
    Dim oInd As IEnumerable(Of Party)


        oComp = From oP In ERM.Parties _
                Where TypeOf (oP) Is Company And _
                CType(oP, Company).Name.StartsWith(sSearchString)

        oInd = From oP In ERM.Parties _
                Where TypeOf (oP) Is Individual And _
                (CType(oP, Individual).FirstName.StartsWith(sSearchString) Or _
                CType(oP, Individual).LastName.StartsWith(sSearchString))

        rptIndividuals.DataSource = oInd
        rptCompanies.DataSource = oComp

        rptCompanies.DataBind()
        rptIndividuals.DataBind()

任何一个转发器中都没有与返回的数据相关的内容，只是项目模板中的一个标签，显示每个查询返回的记录数。

对我来说，我必须绑定到父类型是没有意义的，我将无法在不首先转换为此类型的情况下访问与Individual和Company关联的属性！

Answer 1

您可以在设置转发器的.ToArray ()属性时使用DataSource来解决此问题...

rptCompanies.DataSource = oComp.ToArray ()

我不相信我知道为什么它有效 - 但我尝试过它似乎解决了这个问题！

在asp.net中绑定到linq继承的类型

1 个答案: