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PODropDownList value is blank when saving a FormView's filtered result
 

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    <p>I have a FormView that is used for viewing, editing and inserting items into a MSSQL database. The FormView is wired up to a LinqDataSource, and I use its <code>Selecting</code> event to filter the data displayed in the FormView based on parameters (columns) passed in the query string.</p> <p>In the FormView I have a DropDownList that displays values from a related table. Everything works as it should except when I try to edit - for some reason, the selected value of the DropDownList is always empty when I try to save the edit (even when I have a value selected). The insert works as it should.</p> <p>I have traced the problem down to my <code>Selecting</code> event where I do the filtering. If I comment out the method that does the filtering, it updates the item successfully - but I can't figure out why the filtering is breaking the update.</p> <p>Here is my (shortened) FormView:</p> <pre><code>&lt;asp:FormView ID="fvData" runat="server" AllowPaging="True" DataKeyNames="ID" DataSourceID="ldsData" ondatabound="fvData_DataBound"&gt; &lt;EditItemTemplate&gt; &lt;table class="pad5"&gt; &lt;tr&gt; &lt;td class="field-name"&gt;AREA:&lt;/td&gt; &lt;td&gt;&lt;asp:DropDownList ID="cboAREA" runat="server" DataTextField="AREA_NAME" DataValueField="AREA1" SelectedValue='&lt;%# Bind("AREA") %&gt;' DataSourceID="ldsAreas" /&gt;&lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td class="field-name"&gt;LOOP:&lt;/td&gt; &lt;td&gt;&lt;asp:TextBox ID="txtLOOP" runat="server" Text='&lt;%# Bind("LOOP") %&gt;' /&gt;&lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td class="field-name"&gt;LOOP DESCRIPTION:&lt;/td&gt; &lt;td&gt;&lt;asp:TextBox ID="txtLOOP_DESCRIPTION" runat="server" Text='&lt;%# Bind("LOOP_DESCRIPTION") %&gt;' style="width: 600px" /&gt;&lt;/td&gt; &lt;/tr&gt; &lt;/table&gt; &lt;asp:Button ID="btnUpdate" runat="server" Text="Update" CommandName="Update" CausesValidation="True" /&gt; &lt;asp:Button ID="btnCancel" runat="server" Text="Cancel" CommandName="Cancel" CausesValidation="False" /&gt; &lt;/EditItemTemplate&gt; &lt;InsertItemTemplate&gt; &lt;table class="pad5"&gt; &lt;tr&gt; &lt;td class="field-name"&gt;AREA:&lt;/td&gt; &lt;td&gt; &lt;asp:DropDownList ID="cboAREA" runat="server" DataTextField="AREA_NAME" DataValueField="AREA1" SelectedValue='&lt;%# Bind("AREA") %&gt;' AppendDataBoundItems="true" DataSourceID="ldsAreas"&gt; &lt;asp:ListItem Text="" Value="" /&gt; &lt;/asp:DropDownList&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td class="field-name"&gt;LOOP:&lt;/td&gt; &lt;td&gt;&lt;asp:TextBox ID="txtLOOP" runat="server" Text='&lt;%# Bind("LOOP") %&gt;' /&gt;&lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td class="field-name"&gt;LOOP DESCRIPTION:&lt;/td&gt; &lt;td&gt;&lt;asp:TextBox ID="txtLOOP_DESCRIPTION" runat="server" Text='&lt;%# Bind("LOOP_DESCRIPTION") %&gt;' style="width: 600px" /&gt;&lt;/td&gt; &lt;/tr&gt; &lt;/table&gt; &lt;asp:Button ID="btnInsert" runat="server" Text="Insert" CommandName="Insert" CausesValidation="True" /&gt; &lt;asp:Button ID="btnCancel" runat="server" Text="Cancel" CommandName="Cancel" CausesValidation="False" /&gt; &lt;/InsertItemTemplate&gt; &lt;/asp:FormView&gt; </code></pre> <p>The LinqDataSource:</p> <pre><code>&lt;asp:LinqDataSource ID="ldsData" runat="server" ContextTypeName="E_and_I.EAndIDataDataContext" EnableDelete="True" EnableInsert="True" EnableUpdate="True" EntityTypeName="" TableName="INSTRUMENT_LOOP_DESCRIPTIONs" onselecting="ldsData_Selecting" OrderBy="ID ASC" &gt; &lt;/asp:LinqDataSource&gt; </code></pre> <p>My <code>ldsData_Selecting</code> method:</p> <pre><code>protected void ldsData_Selecting(object sender, LinqDataSourceSelectEventArgs e) { EI.FilterData&lt;INSTRUMENT_LOOP_DESCRIPTION&gt;(ref e, db.INSTRUMENT_LOOP_DESCRIPTIONs, this.db); } </code></pre> <p>And finally <code>EI.FilterData</code>:</p> <pre><code>public static void FilterData&lt;T&gt;(ref LinqDataSourceSelectEventArgs e, IEnumerable&lt;T&gt; source, EAndIDataDataContext db) { if (HttpContext.Current.Request.QueryString.Keys.Count &gt; 0) { var result = source.AsQueryable(); bool filtered = false; // get column names var columnNames = db.Mapping.MappingSource.GetModel(typeof(EAndIDataDataContext)).GetMetaType(typeof(T)).DataMembers; foreach (string key in HttpContext.Current.Request.QueryString.Keys) { string val = HttpContext.Current.Request.QueryString[key]; // check the query string key exists as a column in the table, etc if (columnNames.SingleOrDefault(c =&gt; c.Name == key) != null &amp;&amp; val.Trim() != "" &amp;&amp; val != "*") { result = result.WhereLike(key, val.Replace("?", "_").Replace("*", "%")); filtered = true; } } if (filtered) e.Result = result; } } </code></pre> <p>Is there any reason filtering the results would break the update (and ONLY the DropDownList's - textboxes work fine)? The filtering works perfectly (that is, the FormView only shows the records based parameters entered by the user); if you're wondering what the <code>WhereLike</code> extension method does, you can check out <a href="https://stackoverflow.com/questions/11512539/using-wildcards-with-a-linqdatasource">this question's</a> answer.</p>
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    1. COTry to write filter code in ldsData_Selecting handler and see what happen? I think something is *wrong* with `ondatabound="fvData_DataBound"`
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    2. COThe filter code is only being executed in the `ldsData_Selecting` event, not `fvData_DataBound`. The `fvData_DataBound` event just sets a label in the FormView if it is in ReadOnly mode.
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