Question

我有一个FormView连接到LinqDataSource，我想通过查询字符串过滤。基本上，如果通过查询字符串传入ID，我只想显示该记录，否则如果没有提供ID，则只显示它们。我已经设法使用几种不同的方法来实现这一点，但是每当我尝试在FormView中保存数据时，我都会遇到异常：Operator '==' incompatible with operand types 'Int32?' and 'Object'。

当我致电FormView.UpdateItem(true)时，会引发上述异常。以下是我如何过滤LinqDataSource：

protected void ldsIncidents_Selecting(object sender, LinqDataSourceSelectEventArgs e)
{
    if (!String.IsNullOrEmpty(Request.QueryString["id"]))
    {
        e.Result = db.Incidents.Where(i => i.Incident_Number == Convert.ToInt32(Request.QueryString["id"]));
    }
}

调用FormView.UpdateItem(true)时会抛出异常。一旦我从上面的Selecting事件中删除代码，一切正常，但我无法再过滤数据。我也尝试动态地将WhereParameters添加到LinqDataSource，但同样的事情发生了。有谁知道为什么会这样或者如何解决它？如果它有帮助，这是我的堆栈跟踪：

Exception Type: System.Web.Query.Dynamic.ParseException
Message: Operator '==' incompatible with operand types 'Int32?' and 'Object'
Stack Trace:
   at System.Web.Query.Dynamic.ExpressionParser.CheckAndPromoteOperands(Type signatures, String opName, Expression& left, Expression& right, Int32 errorPos)
   at System.Web.Query.Dynamic.ExpressionParser.ParseComparison()
   at System.Web.Query.Dynamic.ExpressionParser.ParseLogicalAnd()
   at System.Web.Query.Dynamic.ExpressionParser.ParseLogicalOr()
   at System.Web.Query.Dynamic.ExpressionParser.ParseExpression()
   at System.Web.Query.Dynamic.ExpressionParser.Parse(Type resultType)
   at System.Web.Query.Dynamic.DynamicExpression.ParseLambda(ParameterExpression[] parameters, Type resultType, String expression, Object[] values)
   at System.Web.Query.Dynamic.DynamicExpression.ParseLambda(Type itType, Type resultType, String expression, Object[] values)
   at System.Web.Query.Dynamic.DynamicQueryable.Where(IQueryable source, String predicate, Object[] values)
   at System.Web.UI.WebControls.DynamicQueryableWrapper.Where(IQueryable source, String predicate, Object[] values)
   at System.Web.UI.WebControls.QueryableDataSourceView.ExecuteQueryExpressions(IQueryable source, QueryContext context)
   at System.Web.UI.WebControls.QueryableDataSourceView.ExecuteQuery(IQueryable source, QueryContext context)
   at System.Web.UI.WebControls.LinqDataSourceView.ExecuteSelect(DataSourceSelectArguments arguments)
   at System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback)
   at System.Web.UI.WebControls.DataBoundControl.PerformSelect()
   at System.Web.UI.WebControls.BaseDataBoundControl.DataBind()
   at System.Web.UI.WebControls.GridView.DataBind()
   at System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound()
   at System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls()
   at System.Web.UI.Control.EnsureChildControls()
   at System.Web.UI.WebControls.CompositeDataBoundControl.get_Controls()
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.DataBoundControlHelper.ExtractValuesFromBindableControls(IOrderedDictionary dictionary, Control container)
   at System.Web.UI.WebControls.FormView.ExtractRowValues(IOrderedDictionary fieldValues, Boolean includeKeys)
   at System.Web.UI.WebControls.FormView.HandleUpdate(String commandArg, Boolean causesValidation)
   at System.Web.UI.WebControls.FormView.UpdateItem(Boolean causesValidation)
   at PRIDE.Pages.Incidents.View.btnSaveIncident_Click(Object sender, EventArgs e) in C:\Users\hopfnejo\Documents\Development Projects\PRIDE\PRIDE\Pages\Incidents\View.aspx.cs:line 317

修改

以下是FormView的ItemUpdating事件的内容：

protected void fvIncident_ItemUpdating(object sender, FormViewUpdateEventArgs e)
{
    TabContainer tc = fvIncident.FindControl("tcMain") as TabContainer;

    e.NewValues["Division"] = (tc.Tabs[0].FindControl("cboDivision") as DropDownList).SelectedValue;
    e.NewValues["Safety"] = (tc.Tabs[0].FindControl("chkSafety") as CheckBox).Checked;
    e.NewValues["Quality"] = (tc.Tabs[0].FindControl("chkQuality") as CheckBox).Checked;
    e.NewValues["Cost"] = (tc.Tabs[0].FindControl("chkCost") as CheckBox).Checked;
    e.NewValues["Production"] = (tc.Tabs[0].FindControl("chkProduction") as CheckBox).Checked;
    e.NewValues["Environment"] = (tc.Tabs[0].FindControl("chkEnvironment") as CheckBox).Checked;
    e.NewValues["Department"] = (tc.Tabs[0].FindControl("cboDepartment") as DropDownList).SelectedValue;
    e.NewValues["Area"] = (tc.Tabs[0].FindControl("cboArea") as DropDownList).SelectedValue;
    e.NewValues["Initiated_By"] = (tc.Tabs[0].FindControl("txtInitiatedBy") as TextBox).Text;
    e.NewValues["KRA_Notes"] = (tc.Tabs[0].FindControl("txtKRANotes") as TextBox).Text;
    e.NewValues["Incident_type"] = (tc.Tabs[0].FindControl("cboIncidentType") as DropDownList).SelectedValue;
    e.NewValues["Aspect_Affected"] = (tc.Tabs[0].FindControl("cboAspectAffected") as DropDownList).SelectedValue;

    e.NewValues["Incident_Level"] = (tc.Tabs[1].FindControl("cboIncidentLevel") as DropDownList).SelectedValue;
    e.NewValues["ADM_Testing_Within_Guidelines"] = (tc.Tabs[1].FindControl("chkADMTestingWithinGuidelines") as CheckBox).Checked;
    e.NewValues["ADM_Testing_Required"] = (tc.Tabs[1].FindControl("chkADMTestingRequired") as CheckBox).Checked;
    e.NewValues["Number_Of_People_Involved"] = (tc.Tabs[1].FindControl("txtNumPeopleInvolved") as TextBox).Text;

    e.NewValues["Mill_State"] = (tc.Tabs[2].FindControl("cboMillState") as DropDownList).SelectedValue;
    e.NewValues["Area_Downtime"] = (tc.Tabs[2].FindControl("txtDowntime") as TextBox).Text;
    e.NewValues["Production_Amount_Lost"] = (tc.Tabs[2].FindControl("txtProductionAmountLost") as TextBox).Text;
    e.NewValues["Production_Actual_or_Estimate"] = (tc.Tabs[2].FindControl("cboProductionActualOrEstimate") as DropDownList).SelectedValue;
    e.NewValues["Production_Units"] = (tc.Tabs[2].FindControl("cboProductionUnits") as DropDownList).SelectedValue;

    e.NewValues["Environmental_Impact"] = (tc.Tabs[3].FindControl("txtEnvironmentalImpact") as TextBox).Text;
    e.NewValues["Environmental_Specialist_Notified"] = (tc.Tabs[3].FindControl("cboEnvironmentalSpecialistNotified") as DropDownList).SelectedValue;
    e.NewValues["Environmental_Incident_Reportable_to_Government"] = (tc.Tabs[3].FindControl("cboEnvironmentalIncidentReportableToGovernment") as DropDownList).SelectedValue;
    e.NewValues["Environmental_Governement_Agency_Involved"] = (tc.Tabs[3].FindControl("txtGovernmentAgencyInvolved") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[3].FindControl("txtDateReported") as TextBox).Text))
        e.NewValues["Environmental_Date_Reported"] = null;
    else
        e.NewValues["Environmental_Date_Reported"] = (tc.Tabs[3].FindControl("txtDateReported") as TextBox).Text;
    e.NewValues["Environmental_Action_Taken"] = (tc.Tabs[3].FindControl("txtEnforcementActionTaken") as TextBox).Text;
    e.NewValues["Environmental_Reference_Number"] = (tc.Tabs[3].FindControl("txtReferenceNumber") as TextBox).Text;

    e.NewValues["Procedures"] = (tc.Tabs[4].FindControl("txtProceduresAffected") as TextBox).Text;
    e.NewValues["Referances"] = (tc.Tabs[4].FindControl("txtReferences") as TextBox).Text;

    e.NewValues["Reviewed_By__BUL_"] = (tc.Tabs[8].FindControl("txtReviewedByBUL") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[8].FindControl("txtSignOffDateBUL") as TextBox).Text))
        e.NewValues["Sign_Off_Date__BUL_"] = null;
    else
        e.NewValues["Sign_Off_Date__BUL_"] = (tc.Tabs[8].FindControl("txtSignOffDateBUL") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[8].FindControl("txtPlannedReviewDate") as TextBox).Text))
        e.NewValues["Planned_Review_Date"] = null;
    else
        e.NewValues["Planned_Review_Date"] = (tc.Tabs[8].FindControl("txtPlannedReviewDate") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[8].FindControl("txtPlannedCompletionDate") as TextBox).Text))
        e.NewValues["Planned_Completion_Date"] = null;
    else
        e.NewValues["Planned_Completion_Date"] = (tc.Tabs[8].FindControl("txtPlannedCompletionDate") as TextBox).Text;
    e.NewValues["Signed_Off_By__BGL_"] = (tc.Tabs[8].FindControl("txtSignedOffByBGL") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[8].FindControl("txtSignOffDateBGL") as TextBox).Text))
        e.NewValues["Sign_Off_Date__BGL_"] = null;
    else
        e.NewValues["Sign_Off_Date__BGL_"] = (tc.Tabs[8].FindControl("txtSignOffDateBGL") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[8].FindControl("txtActualReviewDate") as TextBox).Text))
        e.NewValues["Actual_Review_Date"] = null;
    else
        e.NewValues["Actual_Review_Date"] = (tc.Tabs[8].FindControl("txtActualReviewDate") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[8].FindControl("txtActualCompletionDate") as TextBox).Text))
        e.NewValues["Actual_Completion_Date"] = null;
    else
        e.NewValues["Actual_Completion_Date"] = (tc.Tabs[8].FindControl("txtActualCompletionDate") as TextBox).Text;
    e.NewValues["Signed_Off_By__Mill_Manager_"] = (tc.Tabs[8].FindControl("txtSignedOffByMillManager") as TextBox).Text;
    if (String.IsNullOrEmpty((tc.Tabs[8].FindControl("txtSignOffDateMillManager") as TextBox).Text))
        e.NewValues["Sign_Off_Date__Mill_Manager_"] = null;
    else
        e.NewValues["Sign_Off_Date__Mill_Manager_"] = (tc.Tabs[8].FindControl("txtSignOffDateMillManager") as TextBox).Text;
}

编辑2

我已尝试在我有处理程序的唯一事件中设置断点，这些事件与LinqDataSource和FormView相关，并且在异常发生之前不会触发任何事件。事件是：

LinqDataSource_Selecting
FormView_ItemUpdating
FormView_DataBound

单击“保存”按钮后，未达到任何断点。它在这里爆炸，不是很有用：

Screenshot

这是我的FormView声明：

<asp:FormView ID="fvIncident" runat="server" DefaultMode="Edit" 
    DataSourceID="ldsIncidents" DataKeyNames="Incident_Number" 
    AllowPaging="True" CssClass="full" ondatabound="fvIncident_DataBound" 
    onitemupdating="fvIncident_ItemUpdating">

我的LinqDataSource声明：

<asp:LinqDataSource ID="ldsIncidents" runat="server" 
    ContextTypeName="PRIDE.PRIDEDataContext" EnableUpdate="True" EntityTypeName="" 
    TableName="Incidents" OrderBy="Incident_Number DESC" 
    onselecting="ldsIncidents_Selecting">
</asp:LinqDataSource>

Answer 1

试试这个。

IQueryable<Incident> query = this.context.Incidents;
string whereCaluse = String.Format("Incident_Value=={0}",Request.QueryString["id"]);
query.Where(whereClause);
e.Result=query;

Answer 2

通过查看异常详细信息，我可以说i.Incident_Number可能是对象类型。

因此，您可以尝试将i.Incident_Number转换为int以及linq表达式。像：

protected void ldsIncidents_Selecting(object sender, LinqDataSourceSelectEventArgs e)
{
    if (!String.IsNullOrEmpty(Request.QueryString["id"]))
    {
        e.Result = db.Incidents.Where(i => Convert.ToInt32(i.Incident_Number) == Convert.ToInt32(Request.QueryString["id"]));
    }
}

Answer 3

也许你应该使用TryParse

protected void ldsIncidents_Selecting(object sender, LinqDataSourceSelectEventArgs e)
{
    if (!String.IsNullOrEmpty(Request.QueryString["id"]))
    {
        int id;
        e.Result = db.Incidents.Where(i => i.Incident_Number == Int32.TryParse(Request.QueryString["id"], out id) ? id : 0);
    }
}

修改

要验证我的建议，您可以执行此操作来检查您的值

    protected void ldsIncidents_Selecting(object sender, LinqDataSourceSelectEventArgs e)
    {
        if (!String.IsNullOrEmpty(Request.QueryString["id"]))
        {
            int id;

            // now you can check the values you gat;
            var queryString = Request.QueryString["id"];
            int iNr =Int32.TryParse(queryString, out id) ? id : 0;

            e.Result = db.Incidents.Where(i => i.Incident_Number == iNr);
        }
    }

Answer 4

嗯，不管你信不信，这是通过实施this SO question的修复来解决的。微软迫切需要解决这个问题。我将寻呼机设置更改为仅显示在FormView的底部，并且poof退出抱怨。

按查询字符串过滤FormView

4 个答案:

修改