Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
400 views
in Technique[技术] by (71.8m points)

c# - Problems with AJAX CascadingDropDown and DropDownList SelectedValue in EditItemTemplate

I am having problem in EditItemTemplate of FormView.

When I use such code in InsertItemTemplate everything works:

<asp:DropDownList ID="Lic_PosiadaczLicencjiIDDropDownList" runat="server" 
    SelectedValue='<%# Bind("Lic_PosiadaczLicencjiID") %>' />
<asp:CascadingDropDown ID="CascadingDropDown1" runat="server" 
    TargetControlID="Lic_PosiadaczLicencjiIDDropDownList" Category="Knt_Kod" 
    ServicePath="~/ManagerLicencjiService.asmx" ServiceMethod="GetKontrahenci">
</asp:CascadingDropDown>  

But when I use exactly the same code in EditItemTemplate I am getting an error that SelectedValue is wrong cause it doesn't exists on the list of elements. I think that the problem is that DropDownList is checked for the values before it is populated by the service. When I run debugger the error occured before breakpoint in the service method.

How to solve this problem?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

<rant>I've found the CCD very clunky and full of poorly-documented workarounds</rant> but here is how you do something as simple as selecting a value when filling the ddl. Note that the selected value is not set on the DDL and that it is being passed to the web service where the selecting is done.

<asp:ScriptManager ID="sm1" runat="server"></asp:ScriptManager>
<asp:FormView ID="fv1" runat="server" DataSourceID="yourDataSource">
    <EditItemTemplate>
        <asp:DropDownList ID="Lic_PosiadaczLicencjiIDDropDownList" runat="server" />
        <asp:CascadingDropDown ID="CascadingDropDown1" runat="server" 
            TargetControlID="Lic_PosiadaczLicencjiIDDropDownList" Category="Knt_Kod" 
            ServicePath="~/ManagerLicencjiService.asmx" ServiceMethod="GetKontrahenci"
            UseContextKey="true" ContextKey='<%# Bind("Lic_PosiadaczLicencjiID") %>'>
        </asp:CascadingDropDown>
    </EditItemTemplate>
</asp:FormView>

<asp:sqldatasource id="yourDataSource"
    selectcommand="select Lic_PosiadaczLicencjiID FROM yourdatabase"
    UpdateCommand="Update yourdatabase set Lic_PosiadaczLicencjiID = @newvalue WHERE Lic_PosiadaczLicencjiID = @Lic_PosiadaczLicencjiID"
    connectionstring="<%$ ConnectionStrings:yourConnectionString %>" 
    runat="server" 
    onupdating="yourDataSource_Updating">
    <UpdateParameters>
        <asp:Parameter Name="newvalue" DbType="String" />
    </UpdateParameters>
</asp:sqldatasource>

code behind:

protected void yourDataSource_Updating(object sender, SqlDataSourceCommandEventArgs e)
{
    e.Command.Parameters["@newvalue"].Value = ((DropDownList)fv1.FindControl("Lic_PosiadaczLicencjiIDDropDownList")).SelectedValue;
}

and in your web service where you are getting your data from you need to add the context key to the signature exactly as shown as it is case sensitive. You then check your returned values for the selected value and set selected = true. If you want selected value instead of selected text then check for x.value instead of x.name.

[WebMethod]
public CascadingDropDownNameValue[] GetKontrahenci(string knownCategoryValues, string category, string contextKey)
{
     CascadingDropDownNameValue[] results = getdata();

     CascadingDropDownNameValue selectedVal = (from x in results where x.name == contextKey select x).FirstOrDefault();
     if (selectedVal != null)
         selectedVal.isDefaultValue = true;

    return results;
}

Hope this helps!


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...