I am getting the data using api but but what is did is when textbox text changes it also changes the value of the currency but after entering a bigger digit and erasing it in onego shows an error.
because you have to set it on any button not on text changed, and zero also goes to not empty and its will call web, so set it on any button to call web
i have solved the problem using a clock. nothing is impossible
Very positive thinking Nice
thank you very much