Question

I’m new to Corona SDK and Lua language and I have some troubles..

so I have this function which sends network request to my site and through json I receive the data. This works great.

The problem is that when I call the variable with the data response outside the listener function, it seems to be nil. I put a small timer to track if the issue was because of the time between the request and response and it seems to be that one (but I’m not sure 100%). I don’t want to use custom delay to perform this operation.

Is there some way to pause the script until the listener response and then continue execution? I have tried with coroutines but I couldn’t solve it..

local data

function networkListener( event )
    if ( event.isError ) then
        print( "Network error!")
    else
    --print ( "RESPONSE: " .. event.response )

        data = json.decode(event.response)

        print( data[1].start_date ) --working great

    end -- end of else statement
end


network.request( "http://localhost/mysite/myphpmethod" , "GET", networkListener )

print(data) -- error: attempt to index upvalue 'data' ( a nil value ) 

local function printIt()
    print( data[1].start_date)
end

timer.performWithDelay(1000, printIt, 1); -- this works 

Answer 1

The HTTP call is asynchronous, which means indeed that your print(data) will almost always be empty, even the performWithDelay might be empty on a bad day.

You will have to design your app in such a way that the game code continues within networkListener() ( in this particular case you would call printIt() from networkListener().

This takes some thinking and re-designing but it is not that bad.