asp.net - How to clear exisiting dropdownlist items when its content changes? -


ddl2 populates based on ddl1 selected value successfully.

my issue data present in ddl2 not clear before appending new data ddl2 content continues grow every time ddl1 changed. 

<asp:dropdownlist id="ddl1" runat="server" datasourceid="sql1" datavaluefield="id1" datatextfield="name2" appenddatabounditems="true" autopostback="true">   <asp:listitem text="all" selected="true" value="0"/> </asp:dropdownlist>  <asp:dropdownlist id="ddl2" runat="server" datasourceid="sql2" datavaluefield="id2" datatextfield="name2" appenddatabounditems="true" autopostback="true">   <asp:listitem text="all" selected="true" value="0"/> </asp:dropdownlist>  <asp:sqldatasource id="sql1" runat="server" selectcommand="sp1" selectcommandtype="storedprocedure"/>  <asp:sqldatasource id="sql2" runat="server" selectcommand="sp2" selectcommandtype="storedprocedure">   <selectparameters>     <asp:controlparameter type="int32" name="id1" controlid="ddl1" propertyname="selectedvalue"/>   </selectparameters> </asp:sqldatasource>

i have tried re-databinding in code behind on selected index change , items.clear little success.

protected sub ddl1_selectedindexchanged(byval sender object, byval e eventargs)     ddl2.items.clear()     ddl2.datasource = sql2     ddl2.databind() end sub

question

how items present in asp:dropdownlist clear before new values populated when dropdownlists content dependent on dropdownlists selected value?

please post code in vb

using ddl.items.clear() clear dropdownlist must sure dropdownlist not set to: 

appenddatabounditems="true"

this option cause rebound data appended existing list not cleared prior binding.

solution

add appenddatabounditems="false" dropdownlist.

now when data rebound automatically clear existing data beforehand.

protected sub ddl1_selectedindexchanged(sender object, e eventargs)     ddl2.datasource = sql2     ddl2.databind() end sub

note: this may not suitable in situations appenddatbound items can cause dropdown append own data on each change of list.

top tip

still want default list item adding dropdown need rebind data?

use appenddatabounditems="false" prevent duplication data on postback , directly after binding dropdownlist insert new default list item.

ddl.items.insert(0, new listitem("select ...", ""))

Comments

Post a Comment

Popular posts from this blog

linux - xterm copying to CLIPBOARD using copy-selection causes automatic updating of CLIPBOARD upon mouse selection -

i've tried various ways coerce xterm (versions 285 , 292) copy selection clipboard clipboard whenever press ctrl-shift-c. promising way far has been, in ~/.xresources, put this: xterm*vt100.translations: #override \ ctrl shift <keypress> c: copy-selection(clipboard) \n\ ctrl shift <keypress> v: insert-selection(clipboard) ctrl-shift-v works perfectly, copying has nuance... if restart xterm, highlighting text puts things in primary clipboard; expected, proper, default behavior. if hit ctrl-shift-c, copies current selection clipboard clipboard. the bug, however, if highlight text after first time pressed ctrl-shift-c, you'll see highlighting copies both primary and clipboard. cannot figure out how stop xterm updating clipboard upon selection... , doesn't make sense me in first place. i said, @ specific point in time, copy selection clipboard... yet starts updating automatically upon selection after doing once... anyone have workaround...
Read more

c++ - qgraphicsview horizontal scrolling always has a vertical delta -

Image
i've subclassed qgraphicsview custom canvas used in cad application. i've reimplemented qgraphicsview::wheelevent check keyboard modifiers control key and, if control key pressed, zoom. i'm trying implement horizontal scroll when user holds shift , uses wheel. the problem i'm having horizontal scrolling always scrolls 0.279. not huge problem, hugely annoying , points else being wrong. so, here questions: is right way implement horizontal scrolling? if not, is? how eliminate delta of 0.279? thanks in advance. code , sample output below void myview::zoom(int delta) { double factor = pow(1.2, delta/abs(delta)); this->scale(factor, factor); } void myview::scrollhorizontal(int level) { qpointf center = maptoscene(viewport()->rect().center()); qdebug() << "center: " << center.x() << ", " << center.y(); centeron(qpointf(center.x() - level, center.y())); } void myview::wheelevent(qwheeleve...
Read more