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

[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

[MarqueeCrew]

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

[MarqueeCrew · Accepted solution]

@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

[mathias_schnoor]

@MarqueeCrew

Hi,

I have tested you solution it works great.

I have expanded your solution without Foo column.

The expansion closer than how I will use it in the future!

Mabe your question was responded already.

It would be nice if you can have a look on it!?!

I have a question still to you:

What is the advantage to use the Detour Tools? The result is always the same.

Mathias

[Juda]

hey Marquee, 

can you please guide me, I am creating a path for each day of current month, if the day doesn't exist yet, I would the system no to create it.

please your thoughts?

Thanks

Juan