[JAVA-5122] Cannot serialize Array property Created: 28/Aug/23 Updated: 31/Jan/24 |
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| Status: | Backlog |
| Project: | Java Driver |
| Component/s: | Codecs, Kotlin |
| Affects Version/s: | 4.10.0 |
| Fix Version/s: | None |
| Type: | Improvement | Priority: | Unknown |
| Reporter: | Andreas Tollkötter | Assignee: | Ashni Mehta |
| Resolution: | Unresolved | Votes: | 0 |
| Labels: | kotlin-quick-wins | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Quarter: | FY24Q4 |
| Documentation Changes Summary: | 1. What would you like to communicate to the user about this feature? |
| Description |
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When trying to serialize a class with an array property, e.g. ```kotlin the BSON serializer fails. This is due to this check in ChildCodecRegistry: https://github.com/mongodb/mongo-java-driver/blob/2fa9f4928c7badc2b022dfc007ce692e82dfe5cd/bson/src/main/org/bson/internal/ChildCodecRegistry.java#L75 `Class<Array<T>>.getTypeArguments` does not actually return 1 but the same as `Class<T>.getTypeArguments`. The simplest fix can be to use `Class.isArray` to hardcode a fallback to one type parameter in that case. This happens on the most recent version, 4.10.2. This bug is actually somewhat important because Kotlin Multiplatform does not support `List`, the usually more natural choice, and requires you to use `Array` instead. |
| Comments |
| Comment by Tom Selander [ 18/Sep/23 ] |
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a.tollkoetter@gmx.de Thanks for your feedback, we'll look at prioritizing this ticket in an upcoming release. |
| Comment by Andreas Tollkötter [ 05/Sep/23 ] |
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Hi ross@mongodb.com. Thanks for your comment. So this is going to be a "Won't fix", if I understand correctly? That is unfortunate. For me as an outsider, it seems like this is something you could add support for without breaking change, even if it hasn't been for several years. Either way, thanks for the pointer to bson-kotlinx. I'll check that out and it sounds like it'll solve the issue for me. Regarding KMM, I use it to share business logic between my frontend and backend, so my domain classes are restricted to use Array instead of List. MongoDB is only addressed from the JVM, so I don't expect to run into problems there. |
| Comment by Ross Lawley [ 05/Sep/23 ] |
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After investigation I can confirm the issue is because there is no native array support for the Bson library which the bson-kotlin library uses. The bson library has been this way for over 10 years and as such its considered as "works as designed". However, there is the bson-kotlinx library that uses kotlinx serialization and because of that it will support arrays, so that could be an alternative. Secondly, when you mentioned Kotlin Multiplatform (KMM) - how are you planning to use KMM? I ask because the underlying kotlin driver will not work on KMM due to some of the Java APIs it uses are also unavailable on KMM. Ross |
| Comment by PM Bot [ 28/Aug/23 ] |
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Hi a.tollkoetter@gmx.de, thank you for reporting this issue! The team will look into it and get back to you soon. |