CODEWITHSUNDEEP
androidiosmysqlluacoronasdk
Ty Team
Ty Team

Reputation: 1

Corona functions and variables

im new to corona and im trying to pull data from mysql database and use that data in the app.

the data fetches correctly but i can access it outside the function.

The function to get the data:

function loginCallback(event) 
if ( event.isError ) then
    print( "Network error!")
else
    print ( "RESPONSE: " .. event.response )
    local data = json.decode(event.response) 
        if data.result == 200 then
            media = data.media_plats 
            print("Data fetched") 
        else
            print("Something went wrong")
        end
    end
return true
end

and then i want to access it here:

function scene:show( event )
    local sceneGroup = self.view
    local phase = event.phase

    if phase == "will" then
    elseif phase == "did" then
        -- make JSON call to the remote server
        local URL = "http://www.mywebsite.com/temp_files/json.php"
        network.request( URL, "GET", loginCallback ) 
        print(data.media_plats) -- returns nil
    end 
end

Thanks in advance.

Upvotes: 0

Views: 79

Answers (1)

ryanpattison
ryanpattison

Reputation: 6251

  1. your callback is invoked asynchronously so network.request will return immediately and probably before the request result has comes back.

    If you want to use data.media_plats (even printing), it should be done/triggered inside the callback.

  2. data is declared as local in the callback so it wont be available outside the function. You can either remove the local to make data a global variable, but maybe that is why you have media = data.media_plats and so printing outside the function with print(media) is probably what you wanted.

.

You can try something like this as a start. It sends the request and the callback triggers a method on the scene to update itself with the newly arrived data. Usually you would set up the view with some placeholder data and let the user know your waiting on data to arrive with a progress indicator of some sort.

Disclaimer: I do not use Corona.

-- updates a scene when media arrives
local function updateWithResponse(scene, media)
    local sceneGroup = self.view
    local phase = event.phase
    print(media)
    -- display using show after
end

--makes a request for data
function scene:show( event )
    if phase == "will" then
    elseif phase == "did" then
        -- make JSON call to the remote server
        local URL = "http://www.mywebsite.com/temp_files/json.php"
        network.request( URL, "GET", responseCallback(self))
    end
end

-- when media arrives, calls function to update scene.
local function responseCallback(scene)
    return function ( event )
        if ( event.isError ) then
            print( "Network error!" )
        elseif ( event.phase == "ended" ) then
            local data = json.decode(event.response) 
            if data.result == 200 then
                print("Data fetched")
                -- finish setting up view here. 
                scene:updateWithResponse(data.media_plats)
            else
                print("Something went wrong")
            end
        end
    end
end

Upvotes: 1

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