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How to deal with missing parameters in URL



Hi All,

I made a DataPage to update a table based on external parameters. 

The problem is that I only want it to update the fields to which parameters were passed.

If no parameters are passed for a specific field, I want to leave it as it is.

I  used "calculated value" for that, but I wasn't able to take any action based on the nonexistence of a parameter.

Let's say I have only 2 clients:

This works: https://myapp.com?Client1=2&Client2=5

This doesn't work: https://myapp.com?Client1=2

Client2 will be filled as blank.


I've tried using conditionals in calculated values like IsNull(), NullIf(), CASE

- IsNull([@Client2],[@field:C2]) --- C2 being the original field name

- CASE WHEN [@Client2] = NULL THEN [@field:C2] ELSE [@Client2]

- CASE WHEN [@Client2] = '' THEN [@field:C2] ELSE [@Client2]

I've also tried replacing parameters and field names with virtual fields, trying to avoid any circular errors.

So I created:

Virtual1 that receives external parameter [@Client2]

Virtual2 that receives Data Source Fields C2

Then I tried the same strategies above using these virtual fields:


WHEN [@cbParamVirtual1] ="" THEN [@cbParamVirtual2]

ELSE [@cbParamVirtual1]


Client 2 keeps receiving blank


One thing that worked was to build the URL with all the parameters and just zero them to control behavior:


When compared to 0, my conditionals will work. But that would make my URL enormous, and I am trying to avoid that.


Any ideas will be very welcome.



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Hello @brunobonna,

As I understood from your description you need to check whether the Virtual field that receives the External parameter is blank.
Please test the following syntax:

CASE WHEN '[@cbParamVirtual1]' = '' THEN ... END


CASE WHEN LEN('[@cbParamVirtual1]') = 0 THEN ... END

Replace [@cbParamVirtual1] with the field name on your DataPage is needed.

Hope this helps. 

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In addition to the previous response, if you are using a parameter or virtual fields in the calculation, enclose them with single quotation marks. I am not sure of the exact reason, but every time I am getting a calculation error, the only issue is that I am missing the quotation marks.


Hope this helps!

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