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datanibbler
Esteemed Contributor

How to identify expressions that rely on no_more_existing fieldnames?

Hi,

I have just discovered by chance that in one of my apps, I had some time ago renamed some fields and one of the expressions in a straight_table chart on the GUI of that app didn't work anymore.

I discovered this by chance because I was just reviewing details of the results delivered by this app and I stumbled over the value not being displayed in the chart when elsewhere the app was telling me that there was a valid entry in that field.

However, that was pure chance and I have already forwarded the results to another team for closer analysis ...

Is there any way I can going forward tell at once if there are any expressions in my apps working on fields that no longer exist under that name?

Thanks a lot!

Best regards,

DataNibbler

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6 Replies

Re: How to identify expressions that rely on no_more_existing fieldnames?

This may not be the most efficient all-at-once method, but it seems to do the job:

In any document you want to check, open the Settings->Expression editor. Enable all expression types. Then select every expression from the list and click 'Edit'. The red wiggly lines will indicate non-existent field names.

MVP
MVP

Re: How to identify expressions that rely on no_more_existing fieldnames?

Not very user-friendly way, but you can go to the expression overview (ctrl+alt+e) window and check expressions (by double clicking on it), it would show 'bad field name(s):..'  error on the expression window.

Re: How to identify expressions that rely on no_more_existing fieldnames?

You bring forward a very good point. Unless we are looking for a error, it is sometime hard to know that something might have changed. I have on occasions used Rob's Document Analyzer to extract all the expressions in an Excel file to check some field names which I thought might have changed, but I guess I knew what has changed. It would be useful if there is way to Red Flag a expression which contains a invalid field name.

datanibbler
Esteemed Contributor

Re: How to identify expressions that rely on no_more_existing fieldnames?

Hi Sunny,

thanks for the reply! So I assume there is no known way - well, looking for "anything out of the ordinary" or even finding it without actually looking is generally more complicated than looking for anything specific.

I am also just looking into the results of the DocumentAnalyzer. That generates a list of fields and a list of the expressions that are being used in an app. Maybe I can make something out of that.

Best regards,

DataNibbler

Re: How to identify expressions that rely on no_more_existing fieldnames?

On top of this being damn difficult to detect, QlikView on average seems pretty capable at detecting simple name changes at every reload and adjusts related expressions accordingly and without user intervention. Can be very confusing at times, especially if you don't want the original expressions to change (for example, after introducing a qualify)...

The main disadvantage is that this trick isn't applied all the time (or you would not be posting this question, would you)

datanibbler
Esteemed Contributor

Re: How to identify expressions that rely on no_more_existing fieldnames?

Hello Peter,

righty. I have noticed in the past that QlikView automatically adapts expressions most of the time - but not always - and sometimes QlikView tries to adjust some expressions and the results are - surprising. You suddenly find some completely different field in an expression.

Well, I'll try to find a way.

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