design setting class property with generated value on save

Development
1

Hello all!

I am currently implementing a generator in the radiology module for the RadiologyStudy entity which generates a unique DICOM Study Instance UID and sets the RadiologyStudy.studyInstanceUID on creation.

I have looked into the approach of using a SaveHandler or the approach used by the Order with its OrderNumberGenerator

I wanted to ask you, what approach you find best in hindsight ? Pros/Cons?

My goal is to set the RadiologyStudy.studyInstanceUID if it is null before saving the entity so that RadiologyStudy.studyInstanceUID is always unique and set.

I also would like to make the generator pluggable so an implementation could choose a different one than the one I supply with the module.

2

Which is the other option you had in mind besides saveHandler?

3

The other option is how Order does it. They implement an interface of the OrderNumberGenerator and use it in saveOrder() to set Order.orderNumber for any new Order’s.

4

That isn’t really another option, that mechanism is a way to let external code to generate order numbers but not set them, however in your case you need a value to be generated and set.

5

well it is another option, it is setting the property in the OrderService.saveOrder(). Even with the SaveHandler I will have to call something like the OrderNumberGenerator generating my UID which will be set.

So the 2 options are setting the property of RadiologyStudy.studyInstanceUid either in

  1. RadiologyStudySaveHandler,
  2. or in the RadiologyStudyService.saveRadiologyStudy()

both will make use of a Uid Generator.

I am leaning towards the RadiologyStudyService.saveRadiologyStudy() but am not sure yet.

6

Well, if the save method is within your module, then you might as well go ahead and do it inside it rather than using a saveHandler

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