topic Re: Large loop - keywords five tabs apart in QlikView

Large loop - keywords five tabs apart

datanibbler — Mon, 13 Oct 2014 12:25:18 GMT

HI,

I always split my script into several parts, one part of the script on one tab.

Now I have one large loop that encompasses two subroutines and several more loops

=> To the effect that the keywords "FROM ..." and "NEXT" are five tabs apart

There should actually be no big issue about that - I can easily put "NEXT [Counter]" instead of just "NEXT" and it should be clear for QlikView what is what

<=> It doesn't work: I have tested what is to be my meta_loop on its own - it parses through an inline_table with six sheet_names which correspond to the names of worksheets in an Excel_workbook.

<=> Still, when I activate this meta_loop around all the other stuff - the first time round, my counter_variable (which is not identical to
any of the "inner" ones, I have named them all differently) is populated all right and so is the variable for the worksheet I'm
currently processing, but after the first iteration is completed, the variable has a NULL value ...

Can anyone help me there?

Thanks a lot!

Best regards,

DataNibbler

Re: Large loop - keywords five tabs apart

datanibbler — Mon, 13 Oct 2014 12:31:54 GMT

Hi,

there is another way I could try: By making it all into one big subroutine

<=> Can I define a subroutine which contains several others?

Re: Large loop - keywords five tabs apart

marcus_sommer — Mon, 13 Oct 2014 12:38:41 GMT

Hi DataNibbler,

I think it's only a small (unexpected) logic-issue. I would run these script within the debugger to see on which step your variable becomes NULL.

- Marcus

Re: Large loop - keywords five tabs apart

marcus_sommer — Mon, 13 Oct 2014 12:42:06 GMT

You could create a routine which called many sub-routines and this is often better then jump from one routine to another and from there jump again ...

- Marcus

Re: Large loop - keywords five tabs apart

datanibbler — Mon, 13 Oct 2014 13:00:24 GMT

Hi Marcus,

I am stepwise_debugging all the time 😉 With the first vrs., the variable (current_list) became NULL just when the first iteration was completed and I was back in the meta_loop.

I'm trying the thing with a meta_subroutine now (that will encompass the two other subroutines).

The difficulty is, I need to pass two variables now - a counter_variable and the current list_name.

I'll keep you posted.

Re: Large loop - keywords five tabs apart

Colin-Albert — Mon, 13 Oct 2014 13:04:09 GMT

Hi DataNibbler.

I often add TRACE commands to output various variables whilst processing the loop so I can debug exactly what is going on from the log files or load progress window without the need to invoke the debugger.

I also add a "Trace === TabName=== ;" as the first line of every tab.

Re: Large loop - keywords five tabs apart

marcus_sommer — Mon, 13 Oct 2014 13:21:21 GMT

Hi DataNibbler,

it looks that these variable will be defined several times - first in your meta-loop and then in your sub-routine and then in your meta-loop again - if yes you need some logic, either you worked with two variables and/or you need to check if the variable-value had changed.

- Marcus

Re: Large loop - keywords five tabs apart

datanibbler — Mon, 13 Oct 2014 14:01:43 GMT

Hi Marcus,

no - I am aware of that issue, so I'm trying to give a new name to each one of my variables and I assign them a NULL value when they are not needed anymore so there can't be any confusion.

I have now successfully established a meta_routine that is called once for every one of my six sheets (six times) and that will itself call the two other subroutines. That works - but only for the first sheet (in the first iteration, my counter "superi" has the value 0 because I use the PEEK() fct. from a small inline_table to determine the name of the sheet to process.

<=> In the second iteration, "superi" has the value 1 and the table_name becomes NULL. I have yet to find out why that is happening.

Best regards,

DataNibbler

P.S.: I am at a loss - when I try only that LOOP, I deactivate the CALL statement and put an EXIT SCRIPT directly after the loop, then it works - I debug it step_by_step and the current_list_variable is properly updated every time.

When, on the other hand, I activate the CALL statement and thus have all the code inbetween, then for the second iteration, "superi" (my counter) is updated from 0 to 1 - and my current_list_variable gets assigned a NULL value ...

P.P.S.: I have just performed a backward search across all tabs for the name of that counter_variable in that meta_loop, but it is definitely unique.

Re: Large loop - keywords five tabs apart

marcus_sommer — Mon, 13 Oct 2014 14:27:51 GMT

Hi DataNibbler,

maybe it's really peek() whereat it generally worked good as loop through a table. Perhaps your syntax missed the tablename: peek('field', $(counter), 'tablename') ?

- Marcus

Re: Large loop - keywords five tabs apart

datanibbler — Mon, 13 Oct 2014 14:33:43 GMT

Hmm ... it generally works very well, yes.

I didn't put the tablename into quotes - I wrote like

>> peek('Name', $(v_List), Sheetnames) <<

I will try with putting both in quotes.

(just to be sure, I tested it again and it is definitely just at the start of the second iteration...)

Re: Large loop - keywords five tabs apart

datanibbler — Mon, 13 Oct 2014 14:39:59 GMT

Hi,

that seems to have been the problem.

Now the script starts the second iteration - but then there's an issue: I am getting a >Field not found< at some point when actually that field should certainly be there - it is in every list.

=> How can I look at the contents of a file in RAM at a specific point in the process of my script without taking the entire loop apart?

Re: Large loop - keywords five tabs apart

Colin-Albert — Mon, 13 Oct 2014 14:44:15 GMT

You could add a qualified load to a test table to see the contents of a table at a particular point in your script.

e.g.

if vLoop = N

qualify * ;

TestTable:

load * resident TableX ;

unqualify * ;

endif; // if Vloop = N

You could add a where clause or first N if you only want a few records included

Re: Large loop - keywords five tabs apart

marcus_sommer — Mon, 13 Oct 2014 14:48:48 GMT

A look into the RAM is more complicated and will need significantly more time as to debug within qv - the suggestions from http://community.qlik.com/people/Colin_Albert about using several trace-statements and using from dummy-tables created per qualify-statement are good - I use the same approach if I can't find my mistakes ...

- Marcus

Re: Large loop - keywords five tabs apart

datanibbler — Mon, 13 Oct 2014 15:08:37 GMT

Hi all,

thanks! I made it. Instead of using the variable, which apparently didn't work for some reason, I used the same PEEK() function inside the meta_subroutine that I had used the first time round to feed one of the six entries of my inline_table into a variable.

I guess that is solved now. A good day's work.

Best regards,

DataNibbler