[bugfix] Allow calling Pickler.derive on non-mirrored types #3289
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adamw
reviewed
Nov 2, 2023
| summonFrom { | ||
| case schema: Schema[T] => fromExistingSchemaAndRw[T](schema) | ||
| case _ => buildNewPickler[T]() | ||
| case _ => | ||
| summonFrom { |
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Hmm looks like we can indeed. The code feels strange, but works, thanks :)
adamw
reviewed
Nov 2, 2023
| case r: Reader[T] => r | ||
| case _ => | ||
| errorForType[T]( | ||
| "Use Pickler.derive[%s] instead of nonMirrorPickler. This method has to be in scope to resolve predefined picklers." |
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is nonMirrorPickler something people should ever use direclty, or our impl detail?
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Yes, but it has to be in public scope. Without it Pickler has issues with deriving ReadWriter for String and some other types. This probably may be worked around, but for now I'd keep it public.
adamw
reviewed
Nov 2, 2023
| // It turns out that summoning a Pickler can sometimes fall into this branch, even if we explicitly state that we want a NotGiven in the method signature | ||
| case m: Mirror.Of[T] => | ||
| errorForType[T]( | ||
| "Found unexpected Mirror. Failed to summon a Pickler[%s]. Try using Pickler.derived or importing sttp.tapir.json.pickler.generic.auto.*" |
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maybe suggest reporting a bug in tapir, if this happens?
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Fixes #3287
For custom type
Twhich are not products or coproducts, one should be able to derive a Pickler by providing implicitReader[T],Writer[T](orReadWriter[T]) andSchema[T], then just callingPickler.derive[T].Currenlty
deriverequires aMirror.Of[T]in its signature, which needs to be removed and moved deeper into asummonFromresolution, to defer determining how to construct the Pickler.Additionally, the
nonMirrorPickler[T]method will have a better error message, indicating that user should usePickler.derived[T]We can't hide
nonMirrorPicklerentirely, because it has to be in scope for correct resolution of predefined picklers (like String, List, Option, etc).