Error with Table and TableView

Solar2D General Questions/Discussion
#1

I’m writing a really simple program that basically generates URLs and stores a history of them.  I store the data in a table, and present it with a tableView.  Everything works perfectly, but (you knew that but was coming, right?) there is one case that generates an error.

If I open the history, and execute the “clear history” function, the table and tableview objects both clear.  However, if I scroll down the history first (even one line), then run the same “clear history” function, I get an error:

<error>

Corona Runtime Error

?:0: attempt to index field ‘?’ (a nil value)

stack traceback:

?: in function <?:1319>

(tail call): ?

history.lua:109: in function <history.lua:103>

?: in function <?:169>

</error>

Here is the code I’m executing:

<code>

for i = #historyList,1,-1 do 

historyTable:deleteRows ({i},{slideUpTransitionTime = 100}) 

table.remove(historyList,i)

end

</code>

The error happens when the first line inside the for loop is run for the first time.  The crazy thing is, if I just reload the program, with no changes to app or files, and run the program, the “clear history” works great!  If I scroll, crash.  If I don’t scroll, success?

Any ideas?  I’ve been beating on this for weeks, because the crashes seemed so random.  Finally (this week) figured out the steps to duplicate the issue, but I just don’t see a way to resolve the problem.

#2

you need to provide more code if you want help.

there is nothing here about the scroll down step

#3

If I got you right, you may need to slide in an if check before the for loop. It should look something like this:

if (#historyList \> 0) then for i = #historyList,1,-1 do historyTable:deleteRows ({i},{slideUpTransitionTime = 100}) table.remove(historyList,i) end end

 or you can apply this check to your :deleteRows() function.

#4

Why not just use the object:deleteAllRows() function for the tableView (https://docs.coronalabs.com/api/type/TableViewWidget/deleteAllRows.html) and then just nil the data table

historyTable:deleteAllRows() historyList = nil

Rob

#5

Thanks all for the responses, especially Rob Miracle!  The first line from your response fixed it.  I can’t use the second line - my List can’t be nil, but using my loop to clear it, and then the deleteAllRows to clear the TableView, worked perfectly!  Thanks again!

#6

you need to provide more code if you want help.

there is nothing here about the scroll down step

#7

If I got you right, you may need to slide in an if check before the for loop. It should look something like this:

if (#historyList \> 0) then for i = #historyList,1,-1 do historyTable:deleteRows ({i},{slideUpTransitionTime = 100}) table.remove(historyList,i) end end

 or you can apply this check to your :deleteRows() function.

#8

Why not just use the object:deleteAllRows() function for the tableView (https://docs.coronalabs.com/api/type/TableViewWidget/deleteAllRows.html) and then just nil the data table

historyTable:deleteAllRows() historyList = nil

Rob

#9

Thanks all for the responses, especially Rob Miracle!  The first line from your response fixed it.  I can’t use the second line - my List can’t be nil, but using my loop to clear it, and then the deleteAllRows to clear the TableView, worked perfectly!  Thanks again!