handling Unknown variable (check if column exists)

mathias_schnoor

Hi!

Is it solution to check if a column exists or not and go ahead with the calculation only if the column exists?

By my example I use the Cross Tab Tool and my output columns are variable.

And so it is possible that a column is not always in the output but if exists in the output than make a calculation.

At the moment I get the error message from the Formula Tool.

Formula (..) Unknown variable "<my varialble>"...

Mathias

Error Message

Parse

Preparation

Accepted answers

MarqueeCrew

@mathias_schnoor,

I am attaching the updated flow here, but have a question for you. Is the file layout consistent except for 'FOO'? There is an easy approach for that. If the field list looks like:

{Foo, Bah, Blubber} or {Bah, Blubber}, then you can create a sample row of data using a text input (like you did already) and UNION it together with your input tool (set your text file as the 1st file in (specific output order configuration). You can then SAMPLE and SKIP the first record. If Foo exists, it will have it's value and if Foo is absent, it will become NULL.

You can then handle the formula based upon IIF(isnull([Foo],0,[Foo})

Just a thought.

You can PM me and we can chat on skype or webex.

Thanks,

Mark

Check if Exists - MC.yxmd

All comments

MarqueeCrew

You could use field info and search for your field. If you find it you can create a variable exists = true, otherwise false. Next you can append that field to your data.

Take the data into a filter for the True data use a formula where you expect the field. For the false data use a formula that doesn't expect it.

Union the true and false (you'll only have all true or all false)

That's my idea.

mathias_schnoor

Hi!

Thank you for your support.

I have try to build a workflow and following your instructions.

But in result set I get to many rows. It would be great if you have a look and make a suggestion fore the right solution.

Mathias

check_if_no_exsits_workflow.yxmd

MarqueeCrew

I will build one in a couple of hours for you.

MarqueeCrew

@mathias_schnoor,

I am attaching the updated flow here, but have a question for you. Is the file layout consistent except for 'FOO'? There is an easy approach for that. If the field list looks like: