Corona Runtime Error “attempt to concatenate field '?' (a nil value)”

Question

i have this 8 question survey in my mobile application handover project. At first the corona did not prompt me any error message and the app works just fine but when i add 2 more question to it i start getting this message error

i am not sure why the error is "a nil value" but my code look something like this.(line 662 to 678)

        function  checkEBASComplete()
        local tempScore = 0
        for i = 1, 10 do
            print("EBAS:"..ebasRating_Arr[i])
            tempScore = tempScore + ebasRating_Arr[i]

            if (ebasRating_Arr[i] == -1) then
                ebasScore = 0
                ebasScore_text.text = "Test Incomplete"
            else
                ebasScore = tempScore
                ebasScore_text.text = tostring(ebasScore)
            end

        end

        tempScore = 0
    end

    checkEBASComplete()

and i have something like this at line 110. i just add 2 more "-1" behide

 local ebasRating_Arr = {-1,-1,-1,-1,-1,-1,-1,-1,-1,-1}

Is anyone able to help me with this? Appreciate for all helps :D

NEW QUESTION------------------------------------------------------

this is my code from line 705 - 711

function saveResults()

        local q = [[UPDATE EBAS_DEP SET rating1=']]..ebasRating_Arr[1] .. [[',rating2=']] .. ebasRating_Arr[2] .. [[',rating3=']] .. ebasRating_Arr[3] .. [[',rating4=']] .. ebasRating_Arr[4] .. [[',rating5=']] .. ebasRating_Arr[5] .. [[',rating6=']] .. ebasRating_Arr[6] .. [[',rating7=']] .. ebasRating_Arr[7] .. [[',rating8=']] .. ebasRating_Arr[8] .. [[',rating9=']] .. ebasRating_Arr[9] .. [[',rating10=']] .. ebasRating_Arr[10] .. [[',rating11=']] .. amtRating_Arr[1] .. [[',rating12=']] .. amtRating_Arr[2] .. [[',rating13=']] .. amtRating_Arr[3] .. [[',rating14=']] .. amtRating_Arr[4] .. [[',rating15=']] .. amtRating_Arr[5] .. [[',rating16=']] .. amtRating_Arr[6] .. [[',rating17=']] .. amtRating_Arr[7] .. [[',rating18=']] .. amtRating_Arr[8] .. [[',rating19=']] .. amtRating_Arr[9] .. [[',rating20=']] .. amtRating_Arr[10] .. [[',rating21=']] .. amtRating_Arr[11] .. [[',ebas_score=']] .. ebasScore ..[[',amt_score=']] .. amtScore ..  [['WHERE id=']].. _G.EBAS_ID..[[';]]
        db:exec( q )
        print(db:errcode(), db:errmsg())

    end

Answer 1

The error occurs when your ebasRating_Arr is too short for the for-loop inside the checkEBASComplete-function. Your original table has only 8 entries but your for-loop checks 10 entries of the table. That means the moment you attempt to access the 9. entry the error occurs because it doesn´t exist.

I would recommend changing the fixed for-loop from 1 to 10 to a relative for-loop 1 to the end of the array. This would work with the #array (or table in Lua) operator. Your code would look like this:

function checkEBASComplete()
    local tempScore = 0
    for i = 1, #ebasRating_Arr do       -- Changed to relative for-loop
        print("EBAS:"..ebasRating_Arr[i])
        tempScore = tempScore + ebasRating_Arr[i]
        if (ebasRating_Arr[i] == -1) then
            ebasScore = 0
            ebasScore_text.text = "Test Incomplete"
        else
            ebasScore = tempScore
            ebasScore_text.text = tostring(ebasScore)
        end
    end
    tempScore = 0
end