asp.net - c# entity , deleting a db record from a drop down list selected value -

how delete record drop down list selected value?

i have populated drop down list database , having problems delete delete button. doing right way? ( sorry if codes messy )

this how populate drop down list:

protected void droptask()     {         droplisttask.datasource = daotask.getall();         droplisttask.datatextfield = "taskname";         droplisttask.datavaluefield = "taskid";          droplisttask.databind();     } 

this delete button :

  protected void btndelete_click(object sender, eventargs e)   {         if (!page.ispostback)         {              model.task del= new model.task();             del.taskid = convert.toint32(droplisttask.selectedvalue);             daotask.delete(del);             daotask.save();         }   } 

i need add postback btn codes, if removed it gives me error says;

the object cannot deleted because not found in objectstatemanager.

so put in postback , error gone. don't know if right way. please advise me how to correct way.

thanks in advance.

this: if (!page.ispostback) means piece of code run on first run of page (so not when click button). button click go asp page post should invert if, in btndelete_click method know postback can skip if altogether.

i believe error went away because, indeed, not executing code in if block, nothing deleted.

i don't know daotask or how persistance in code way of deleting object db not sound right... creating new 1 , assigning different id flow should different:

first find existing object based on id, delete it:

// don't know if 'find' method need, should check based on // libraries using saving/loading db model.task del = daotask.find(convert.toint32(droplisttask.selectedvalue)); daotask.delete(del); daotask.save(); 

googling error got should have pointed in right direction fact problem db code, rather asp postback: the object cannot deleted because not found in objectstatemanager

update

based on comment should this:

model.task del = daotask.gettask(droplisttask.selecteditem.text); daotask.delete(del); daotask.save(); 

by way, add gettask(int id) method daotask class able find tasks id rather name.