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Nested Repeaters - One Datasource depends on another

Posted on 2010-11-15
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Last Modified: 2012-08-13
I have a dataset as follows:

Degree category  (dataset: degrees)  : ID = 1
-- degree details 1
-- degree details 2

Course category (dataset: courses)  --> parameter ID = 1
-- course details 1
-- course details 2

Degree category2  (dataset: degrees)  : ID = 2
-- degree details 1
-- degree details 2

Course category (dataset: courses)  --> parameter ID = 2
-- course details 1
-- course details 2

As the page iterates through the first record in the degree dataset, I need to grab the ID value and use it as a parameter in my second dataset (courses).

I tried passing the value into a hidden field then grabbing the value from that in the code behind, but each time I test, I'm getting a null value in the hidden field, which is causing the application to terminate. Could it be that I'm doing this in the page load and the hidden field isn't populated yet? If so, how can I make sure I grab that value at the right moment?
<asp:SqlDataSource ID="dsDegree" runat="server" 
        ConnectionString="" 
        SelectCommand="sp_degreeRecord" SelectCommandType="StoredProcedure">       
    </asp:SqlDataSource>
        
    <asp:SqlDataSource ID="dsCourses" runat="server" 
        ConnectionString="" 
        SelectCommand="sp_courseRecords" SelectCommandType="StoredProcedure">     
    </asp:SqlDataSource>

<asp:Repeater ID="degreeDetails" runat="server" DataSourceID="dsDegree"> 
<ItemTemplate>
    <asp:HiddenField ID="hdnID" runat="server" Value='<%# Eval("ID") %>' />
    <h1><asp:Label ID="lblDegreeName" runat="server" Text='<%# Eval("degreeName") %>'></asp:Label></h1>
    <p><asp:Literal ID="litDescription" runat="server" Text='<%# Eval("description") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblAdmissionHdr" runat="server" Text="Admission"></asp:Label></h2>
    <p><asp:Literal ID="litAdmission" runat="server" Text='<%# Eval("admission") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblStandardsHdr" runat="server" Text="Standards"></asp:Label></h2>
    <p><asp:Literal ID="litStandards" runat="server" Text='<%# Eval("standards") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblAdvisingHdr" runat="server" Text="Advising"></asp:Label></h2>
    <p><asp:Literal ID="litAdvising" runat="server" Text='<%# Eval("advising") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblPrerequisitesHdr" runat="server" Text="Prerequisites"></asp:Label></h2>
    <p><asp:Literal ID="litPrerequisites" runat="server" Text='<%# Eval("prerequisites") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblRequirementsHdr" runat="server" Text="Requirements"></asp:Label></h2>
    <p><asp:Literal ID="litRequirements" runat="server" Text='<%# Eval("requirements") %>'></asp:Literal></p>
    
        <asp:Repeater ID="rptCourseInfo" runat="server" DataSourceID="dsCourses">
        <HeaderTemplate><table width="95%" cellpadding="3" cellspacing="0" border="0" align="center"></HeaderTemplate>
        <ItemTemplate>
        <tr>
        <td width="5%">&nbsp;</td>
        <td width="15%"><%# Eval("subjectID") %> <%# Eval("courseNumber") %></td>
        <td align="left" valign="top" width="70%"><%# Eval("courseName") %></td>
        <td align="left" valign="top" width="10%">.....<%# Eval("credits") %></td>
        </ItemTemplate>
        <FooterTemplate></table></FooterTemplate>
        </asp:Repeater>
        
    <p><asp:Literal ID="litOther" runat="server" Text='<%# Eval("otherInfo") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblCertificationHdr" runat="server" Text="Certification"></asp:Label></h2>
    <p><asp:Literal ID="litCertification" runat="server" Text='<%# Eval("certification") %>'></asp:Literal></p>
    </ItemTemplate>
    </asp:Repeater>

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protected void Page_Load(object sender, EventArgs e)
        {
         
            string id = Request.QueryString["ID"];

            dsDegree.SelectParameters.Add(new Parameter("ID", TypeCode.Int32)); 
            dsDegree.SelectParameters["ID"].DefaultValue = id;          

            String subcatID = ((HiddenField)Page.FindControl("hdnID")).Value;

            dsCourses.SelectParameters.Add(new Parameter("ID", TypeCode.Int32));
            dsCourses.SelectParameters["ID"].DefaultValue = subcatID;

        }

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Question by:vcbertini
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6 Comments
 
LVL 12

Accepted Solution

by:
jagssidurala earned 500 total points
ID: 34138447
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Author Comment

by:vcbertini
ID: 34140764
I have tried a multitude of what was suggested on those pages and here is what I am getting...

"c" is being returned as Null even though the data source clearly exists (see 2nd code attachment).  

and it won't add a parameter to a datasource it isn't finding, thus the error.
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="CatalogDegree.ascx.cs" Inherits="RooseveltCMS.layouts.catalogDegreeSublayout" %> 
 
    <asp:SqlDataSource ID="dsDegree" runat="server" 
        ConnectionString="" 
        SelectCommand="sp_degreeRecord" SelectCommandType="StoredProcedure">       
    </asp:SqlDataSource>
    
    <asp:SqlDataSource ID="dsCourses" runat="server" 
        ConnectionString="" 
        SelectCommand="sp_courseRecords" SelectCommandType="StoredProcedure">     
    </asp:SqlDataSource> 
       
<div id="CenterColumn">
<form runat="server">

<asp:Repeater ID="degreeDetail" runat="server" DataSourceID="dsDegree" OnItemDataBound="R1_ItemDataBound"> 
<ItemTemplate>
    <asp:HiddenField ID="hdnID" runat="server" Value='<%# Eval("ID") %>' />
    <h1><asp:Label ID="lblDegreeName" runat="server" Text='<%# Eval("degreeName") %>'></asp:Label></h1>
    <p><asp:Literal ID="litDescription" runat="server" Text='<%# Eval("description") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblAdmissionHdr" runat="server" Text="Admission"></asp:Label></h2>
    <p><asp:Literal ID="litAdmission" runat="server" Text='<%# Eval("admission") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblStandardsHdr" runat="server" Text="Standards"></asp:Label></h2>
    <p><asp:Literal ID="litStandards" runat="server" Text='<%# Eval("standards") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblAdvisingHdr" runat="server" Text="Advising"></asp:Label></h2>
    <p><asp:Literal ID="litAdvising" runat="server" Text='<%# Eval("advising") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblPrerequisitesHdr" runat="server" Text="Prerequisites"></asp:Label></h2>
    <p><asp:Literal ID="litPrerequisites" runat="server" Text='<%# Eval("prerequisites") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblRequirementsHdr" runat="server" Text="Requirements"></asp:Label></h2>
    <p><asp:Literal ID="litRequirements" runat="server" Text='<%# Eval("requirements") %>'></asp:Literal></p> 
        <asp:Repeater ID="courseDetail" runat="server" DataSourceID="dsCourses">
        <HeaderTemplate><table width="95%" cellpadding="3" cellspacing="0" border="0" align="center"></HeaderTemplate>
        <ItemTemplate>
        <tr>
        <td width="5%">&nbsp;</td>
        <td width="15%"><%# Eval("subjectID") %> <%# Eval("courseNumber") %></td>
        <td align="left" valign="top" width="70%"><%# Eval("courseName") %></td>
        <td align="left" valign="top" width="10%">.....<%# Eval("credits") %></td>
        </ItemTemplate>
        <FooterTemplate></table></FooterTemplate>
        </asp:Repeater>
        
    <p><asp:Literal ID="litOther" runat="server" Text='<%# Eval("otherInfo") %>'></asp:Literal></p>
    <h2><asp:Label ID="lblCertificationHdr" runat="server" Text="Certification"></asp:Label></h2>
    <p><asp:Literal ID="litCertification" runat="server" Text='<%# Eval("certification") %>'></asp:Literal></p>
    </ItemTemplate>
    </asp:Repeater>
</form>
    </div>

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protected void R1_ItemDataBound(Object Sender, RepeaterItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem) 
            {
               // Find the Inner DataSource control in this Row. 
               SqlDataSource c = (SqlDataSource)e.Item.FindControl("dsCourses");

                // Create the parameter for the child datasource
                c.SelectParameters.Add(new Parameter("ID", TypeCode.String));

                // Set the SelectParameter for this DataSource control by re-evaluating the field that is to be passed.
                c.SelectParameters["ID"].DefaultValue = DataBinder.Eval(e.Item.DataItem, "ID").ToString();
            }
        }
    }

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LVL 12

Assisted Solution

by:jagssidurala
jagssidurala earned 500 total points
ID: 34142098
Place "dsCourses" datasource in main repeater.

and third i have given above will satisfy your needs, try once like that
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Author Comment

by:vcbertini
ID: 34142126
I tried that, the dscourses entry disappears from the designer page, and then I get an error that the object reference cannot be found.
0
 
LVL 12

Expert Comment

by:jagssidurala
ID: 34142205
you need to find from main control after placing inside
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Author Closing Comment

by:vcbertini
ID: 34147895
Not sure what changed in my development environment, but when I moved the dataset into the main Repeater, today it didn't disappear - it worked. Thanks for pointing me in the right direction.
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