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POChanging dropdownlist selection causes full postback. (it's more interesting than it sounds)
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  1. POChanging dropdownlist selection causes full postback. (it's more interesting than it sounds)
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    copied!<p>Here's the scenario.</p> <p>I have a search page with a TextBox that allows someone to type in a search term and press enter. (Which fires TextChanged). I have a DropDownList that specifies the kind of search that will be performed. It is defined in the markup as follows:</p> <pre><code> &lt;asp:DropDownList ID="lstSearchType" runat="server" AutoPostBack="false"&gt; &lt;asp:ListItem Value="0"&gt;Last, First&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="1"&gt;Last&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="2"&gt;First&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="3"&gt;Liberty ID&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="4"&gt;E-mail&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="5"&gt;Telephone&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="6"&gt;Birthday (exact m/d/yyyy)&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="7"&gt;SSN (exact ###-##-####)&lt;/asp:ListItem&gt; &lt;asp:ListItem Value="8"&gt;Address&lt;/asp:ListItem&gt; &lt;/asp:DropDownList&gt; </code></pre> <p>As you can see, AutoPostBack is set to false, and there is no event hookup.</p> <p>Pressing enter fires the OnTextChanged event for the TextBox, which performs a search and updates a GridView in an UpdatePanel. This UpdatePanel has its UpdateMode set to conditional and has one trigger: the TextChanged event of the search TextBox. </p> <p>It's very simple. </p> <p>And it works beautifully, almost. </p> <p>Whenever I change the search type, the very next search does a full postback. All subsequent searches do partial postbacks (as desired) unless I change the search type again. </p> <p>There is one exception to this rule: if I load the page and immediately change the search type, it doesn't do a full postback. So the first change of the DropDownList before any postback (full or partial) does not trigger a full postback. </p> <p>Full Disclosure: I'm doing a lot of JavaScript to change the appearance of the gridview during async requests. I don't detail it here because it seems unrelated. This problem only occurs when a DropDownList with no JavaScript wired up is changed. </p> <p>Any ideas? </p> <p>This is driving me crazy. Everything else is working.</p> <p>Thanks in advance, Clif</p>
 

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