Pinescript - Re-initialize alert variable

Question

I am trying to do something very basic in Pine, but I am completely stumped on how to solve the issue. In summary I have an alert which need to update a fixed price level on a user input. The alert places an order on the chart, and I can update the price level as I see fit. When the alert is re-triggered (once per bar close) then the order is placed at the new level

However, the only behaviour I can see is that the initial variable is forever fixed until I remove the alert completely from the alert console and re-add the alert. For example, if I apply the below alert to the chart the fp=0 will not change even though I change the user input after the alert has been added.

Any help is much appreciated. Or if you need more info please let me know. Thanks in advance

var symbol = syminfo.basecurrency + "/" + syminfo.currency
var avPrefix = "e=oandapractice "  + " s=" + symbol + ""
var TpPrice = 0.000000
t_TpPrice = input(title="TP Price?", type=input.float,  defval=0.000000, step=0.000001)


if (barstate.isrealtime) 
    TpPrice := t_TpPrice
    clearOrder = avPrefix + " c=order\n "
    tpTrigger = avPrefix + " b=sell" + " q=20000" + " t=limit" + " fp=" + tostring(TpPrice)
    alert( message=clearOrder + tpTrigger ,freq=alert.freq_once_per_bar_close)   

Answer 1

You are using input constant variable, which is not changes after compilation. You will need to recreate alert, if you want to use it with another value from input.