c# - ASP.NET GridView won't populate from changing SqlDataSource.SelectCommand if Textbox is empty -
i'm using textbox , dropdownlist filter database searches. i'm using sqldatasource blank selectcommand , setting command in codebehind depending on user has typed in , selected in dropdownlist. if statements in codebehind work if txtfindbook != "".
before explain anymore here code:
default.aspx
<asp:content id="bodycontent" contentplaceholderid="maincontent" runat="server"> <div class="jumbotron"> <h1>find book...</h1> <p> <asp:textbox id="txtfindbook" runat="server" width="700px"></asp:textbox> <asp:dropdownlist id="ddlgenres" runat="server"></asp:dropdownlist> <asp:button id="btnfindbook" runat="server" text="search" onclick="btnfindbook_click" height="36px" /> <p>enter search terms in box above, click "search" begin search.</p> <asp:label id="label1" runat="server" text=""></asp:label> </div> <div class="searchresults"> <asp:gridview id="gvsearchresults" runat="server" autogeneratecolumns="false" datakeynames="id" datasourceid="sqldatasourcesearchresults"> <columns> <asp:boundfield datafield="id" headertext="id" readonly="true" insertvisible="false" sortexpression="id"></asp:boundfield> <asp:boundfield datafield="bookid" headertext="bookid" sortexpression="bookid"></asp:boundfield> <asp:boundfield datafield="title" headertext="title" sortexpression="title"></asp:boundfield> <asp:boundfield datafield="author" headertext="author" sortexpression="author"></asp:boundfield> <asp:boundfield datafield="isbn_10" headertext="isbn_10" sortexpression="isbn_10"></asp:boundfield> <asp:boundfield datafield="isbn_13" headertext="isbn_13" sortexpression="isbn_13"></asp:boundfield> <asp:boundfield datafield="dewey" headertext="dewey" sortexpression="dewey"></asp:boundfield> <asp:boundfield datafield="genre" headertext="genre" sortexpression="genre"></asp:boundfield> <asp:checkboxfield datafield="ischeckedout" headertext="ischeckedout" sortexpression="ischeckedout"></asp:checkboxfield> <asp:boundfield datafield="checked_out_to_whome" headertext="checked_out_to_whome" sortexpression="checked_out_to_whome"></asp:boundfield> <asp:boundfield datafield="due_date" headertext="due_date" sortexpression="due_date"></asp:boundfield> </columns> </asp:gridview> <asp:sqldatasource runat="server" id="sqldatasourcesearchresults" connectionstring='<%$ connectionstrings:defaultconnection %>' selectcommand=""> <selectparameters> <asp:controlparameter controlid="txtfindbook" propertyname="text" name="title" type="string"></asp:controlparameter> <asp:controlparameter controlid="ddlgenres" propertyname="selectedvalue" defaultvalue="select genre" name="genre" type="string"></asp:controlparameter> </selectparameters> </asp:sqldatasource> </div> default.aspx.cs
public partial class _default : page { static string connstring = system.configuration.configurationmanager.connectionstrings["defaultconnection"].connectionstring; sqlconnection conn = new sqlconnection(connstring); protected void page_load(object sender, eventargs e) { if (!ispostback) { /*there no point in populating dropdownlist everytime there post back. */ populateddlgenres(); } } protected void btnfindbook_click(object sender, eventargs e) { if (txtfindbook.text != "" && ddlgenres.selecteditem.text != "select genre") { sqldatasourcesearchresults.selectcommand = "select * [books] (([title] '%' + @title + '%') , ([genre] = @genre)) order [title]"; label1.text = "if statement 1."; } else if (txtfindbook.text == "" && ddlgenres.selecteditem.text != "select genre") { label1.text = "if statement 2."; sqldatasourcesearchresults.selectcommand = "select * [books] ([genre] = @genre)"; } else if (txtfindbook.text == "" && ddlgenres.selecteditem.text == "select genre") { sqldatasourcesearchresults.selectcommand = "select * [books]"; label1.text = "if statement 3."; } else if(txtfindbook.text != "" && ddlgenres.selecteditem.text == "select genre") { sqldatasourcesearchresults.selectcommand = "select * [books] ([title] '%' + @title + '%') order [title]"; label1.text = "original."; } } private void populateddlgenres() { try { using (sqlconnection con = new sqlconnection(connstring)) { sqlcommand cmd = new sqlcommand("select * genres", con); con.open(); ddlgenres.datasource = cmd.executereader(); ddlgenres.datatextfield = "genretext"; //ddlgenres.datavaluefield = ""; //we aren't using because text it's own value. ddlgenres.databind(); //must go last! } } catch (exception ex) { // handle error } ddlgenres.items.insert(0, new listitem("select genre", "0")); } } now if add txtfindbook.text = "a"; @ beginning of if statements 2 & 3 populate gvsearchresults on postback.
is there someway can still have if statements 2 & 3 work while keeping txtfindbook.text blank?
modify sqldatasource adding default value of null title property defined on , should trick. not need labels, didn't understand label thing anyway.
<asp:sqldatasource runat="server" id="sqldatasourcesearchresults" connectionstring='<%$ connectionstrings:defaultconnection %>' selectcommand=""> <selectparameters> <asp:controlparameter controlid="txtfindbook" propertyname="text" defaultvalue="null" name="title" type="string"></asp:controlparameter> <asp:controlparameter controlid="ddlgenres" propertyname="selectedvalue" defaultvalue="select genre" name="genre" type="string"></asp:controlparameter> </selectparameters> </asp:sqldatasource>
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