quick question on savedstate handling is there a way to save

Question

quick question on savedstate handling is there a way to save only a partial bit of your viewmodel e g just an ID to reload data with or a Paging offset e g I didn t see anything in the API to do this

Mikolaj Leszczynski · Answer

There is no Orbit API for this as we merely send the state off to be serialized using the object s user defined serializer parceler Typically one would use kotlin s ` Parcelize` and with it you can alter the generated serializer by excluding parts of the state or completely overriding the parceler Here s a great article explaining how to do that and more <https bladecoder medium com a study of the parcelize feature from kotlin android extensions 59a5adcd5909>

kenkyee · Answer

Ahh add IgnoredOnParcel everywhere slightly smiling face Is there any way to add a parcel size checker We ve had people stuff rest responses into savedstate pensive

Mikolaj Leszczynski · Answer

< kenkyee> Android has a 1MB limit runtime check which will throw an exception if this is exceeded What would you need beyond that I m not sure you can alter the generated code but you could write a lint check to make sure the only parcelable things inside your state include only e g primitive classes and Strings

kenkyee · Answer

Hmm Lint check is a good idea When Android s check happens it s usually too late because it is harder to find in the code base

kenkyee · Answer

played w the IgnoredOnParcel a bit and it doesn t look like a great solution because it won t work on constructor params accessor syntax looks pretty bad if you use a regular class too And can t use a subclass like this that s parcelable because container expects a parcelable state class ```data class Person val info PersonInfo val items PagedList lt Item gt = null Parcelize data class PersonInfo val firstName String val lastName String val age Int Parcelable```

kenkyee · Answer

maybe I should back up a bit and describe a use case you ve probably hit in your Babylon app

kenkyee · Answer

use case for what I was trying to use it for was a PagingOffset on an infinite loading screen So on next app resurrection it ll load up to the point that you were at How would you do something like this

Mikolaj Leszczynski · Answer

If this is a really long list I assume yes since it s paged I would cache the results in the DB and load it from there Otherwise just parcel the offset and do another network request but this can be bad for performance and data usage Re Parcelables You can provide your own `Parceler` to only save what you need or worst case scenario you just have to implement the parcelable manually Both approaches suck but it s easier to achieve exactly what you need I wasn t aware of problems using ` IgnoredOnParcel` like this it seems like a glaring omission thinking face Haven t used ` Parcelize` a lot myself so I assumed it would just work PS We have work to do in this respect currently we re forcing you to use `Parcelable` which as you can see comes with some inherent problems And it won t work cross platform which is why we need a better solution anyway

Oleksii Malovanyi · Answer

Just sharing the experience we decided to use Paging 3 x lib + Compose so it s completely extracted out of the state of course in this case if the process is destroyed the scroll position is forgotten but pros and cons we think it s not a big deal for our use case but helps implementing it very straightforward

Oleksii Malovanyi · Answer

Anyway in my experience you d never want a big list of something in your state if it s saved to parcel gt this causes all sort of errors which extremely hard to debug due to size limit

kenkyee · Answer

you can t just leave it in the DB e g with Compose The list is part of your state There is actually a KMP library that adds support for Parcelable <https github com icerockdev moko parcelize>

kenkyee · Answer

Trying to avoid Paging Lib because the initial betas I tried were super buggy slightly smiling face But this isn t necessarily limited to paging that s just an example where I wanted to save a partial state into savedstate

kenkyee · Answer

Might be a good opportunity to use KSP to generate the parcelable s parcelizer This way you could also validate that people aren t stuffing giant blobs into savedstate too

Mikolaj Leszczynski · Answer

gt you can t just leave it in the DB e g with Compose The list is part of your state This doesn t mean you can t cache it in the DB and load it from there when you restore

Mikolaj Leszczynski · Answer

gt Might be a good opportunity to use KSP to generate the parcelable s parcelizer This way you could also validate that people aren t stuffing giant blobs into savedstate too That s like an entirely new parcelization library project sweat smile

Oleksii Malovanyi · Answer

My bet is it would be extremely hard to set a limit on parcelable anyway cause android has a limit on the whole parcelable for activity and it involves a lot of view s states not only the one you save explicitly

kenkyee · Answer

Devs are sometimes crazy and parcelize everything some spots of our current codebase save off entire REST API responses face palm

Oleksii Malovanyi · Answer

btw paging 3 works really nice with compose now gt at least we can t see any problems