FHIR Chat · Constraining integer in FSH

Stream: shorthand

Topic: Constraining integer in FSH

Nathan Davis (Sep 29 2020 at 15:18):

How do I restrict valueInteger to values of 0-10 in FSH?

Jens Villadsen (Sep 29 2020 at 15:44):

Sounds like either an fp invariant or a valueset binding to me

Chris Moesel (Sep 29 2020 at 16:13):

Yes, I think you'd need to create in invariant using FHIRPath. First you create the Invariant. Something like this:

Invariant:  zero-to-ten
Description: "Value must be an integer between 0 and 10 (inclusive)"
Expression: "$this >= 0 and $this <= 10"
Severity:   #error

And then in your profile (assuming on Observation):

* valueInteger obeys zero-to-ten

Or if value[x] is restricted to only allow integer anyway, you can just do:

* value[x] obeys zero-to-ten

Nathan Davis (Sep 29 2020 at 16:32):

@Jens Villadsen @Chris Moesel Thank you!

Grahame Grieve (Sep 29 2020 at 21:06):

why not use minValue and maxValue ?

Chris Moesel (Sep 29 2020 at 21:38):

Honestly? Because I forgot they exist?

Chris Moesel (Sep 29 2020 at 21:41):

OK. So a better way would be:

* valueInteger ^minValueInteger = 0
* valueInteger ^maxValueInteger = 10

Or if value[x] is restricted to only allow integer anyway:

* value[x] ^minValueInteger = 0
* value[x] ^maxValueInteger = 10

Thanks for keeping me honest, @Grahame Grieve!

Jens Villadsen (Sep 30 2020 at 10:21):

Lol

Moritz Kähler (Dec 07 2021 at 08:08):

Hi, I'm not sure if it's correct to post the question here.
If I try to express min/max value in the same way for valueQuantity it does not work.

valueQuantity ^minValueQuantity = 0
valueQuantity ^maxValueQuantity = 100

see example here
https://fshschool.org/FSHOnline/#/share/3pRcOuL

causes:
error Cannot assign number value: 0. Value does not match element type: Quantity
Line: 12
error Cannot assign number value: 100. Value does not match element type: Quantity
Line: 13

In XML/JSON format this is supported.
Any ideas?

Chris Moesel (Dec 07 2021 at 13:30):

Hi @Moritz Kähler. Assigning a Quantity in FSH requires you to specify the units. So you need to do something more like this:

* valueQuantity ^minValueQuantity = 0 'kg'
* valueQuantity ^maxValueQuantity  = 100 'kg'

If you really wanted to specify the value only (without units), then you'd need to do this:

* valueQuantity ^minValueQuantity.value = 0
* valueQuantity ^maxValueQuantity.value  = 100

BUT... I would not recommend that. For the min/max to be meaningful, you really ought to set the units.

Moritz Kähler (Dec 07 2021 at 14:48):

Hi Chris Moesel, thank you for the quick answer.
I can build the .fsh files now. But if I validate resources against the profile (using hapi server) the validation does not fail if I provide a value less than 0.
If I use Invariants, the validation fails. Is this an issue with hapi or is this the intended behavior?

Chris Moesel (Dec 07 2021 at 20:10):

That sounds like a HAPI validator issue to me.

Grahame Grieve (Dec 08 2021 at 03:56):

you're right. The validator will start validating min and max quantities when next released

Moritz Kähler (Dec 08 2021 at 08:19):

Thanks for confirming the issue with validator. Good to know, that this will be fixed in the next release.

Last updated: Apr 12 2022 at 19:14 UTC

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FHIR Chat · Constraining integer in FSH · shorthand