c# - 按查询字符串过滤 FormView

Question

我有一个连接到 LinqDataSource 的 FormView，我想按查询字符串对其进行过滤。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，则只显示所有记录。我已经设法使用几种不同的方法让它工作，但是每次我尝试将数据保存在 FormView 中时，我都会遇到异常:Operator '==' incompatible with operand types 'Int32?'和“对象”。

当我调用 FormView.UpdateItem(true) 时出现上述异常。下面是我如何过滤 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"]));
    }
}

当我调用 FormView.UpdateItem(true) 时抛出异常。从上面的 Selecting 事件中删除代码后，一切正常，但我无法再过滤数据。我也尝试过将 WhereParameters 动态添加到 LinqDataSource，但同样的事情发生了。有谁知道为什么会这样或如何解决？如果有帮助，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

---

编辑

下面是 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

我已经尝试在我拥有与 LinqDataSource 和 FormView 相关的处理程序的唯一事件中设置断点，并且在异常发生之前没有触发任何事件。事件是:

• LinqDataSource_Selecting
• FormView_ItemUpdating
• FormView_DataBound

单击“保存”按钮后，我的所有断点都没有到达。这里炸了，用处不大:

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">

还有我的 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;