Support absent attributes/relationships in resource decoding#20
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The JSON:API spec allows a resource object's attributes and relationships members to be entirely absent, but Resource.init(from:) previously threw keyNotFound whenever either key was missing. Add an opt-in EmptyRepresentable protocol so a ResourceDefinition can declare tolerance for a missing key, and teach @ResourceWrapper to auto-synthesize that conformance when every attribute/relationship property is Optional. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
alanf
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July 23, 2026 17:21
NicoMulet
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Jul 24, 2026
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LGTM! Thanks for adding this important behavior to the library
| self.attributes = attributes | ||
| } else if !container.contains(.attributes), let emptyType = Attributes.self as? any EmptyRepresentable.Type | ||
| { | ||
| self.attributes = emptyType.empty as! Attributes |
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Can we add this cast to the if condition, so that we avoid of making of force cast
| } else if !container.contains(.relationships), | ||
| let emptyType = Relationships.self as? any EmptyRepresentable.Type | ||
| { | ||
| self.relationships = emptyType.empty as! Relationships |
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Same comment for this cast
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| } catch DecodingError.keyNotFound { | ||
| // then | ||
| } |
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We need an extra catch block in order to also fail the test if the error is not the one we were expecting
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| } catch DecodingError.keyNotFound { | ||
| // then | ||
| } |
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Same for this do-catch block
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Support absent
attributes/relationshipsin resource decodingPer the JSON:API spec, a resource
object's
attributesandrelationshipsmembers are optional — onlytype/idare required.Resourcepreviously threwkeyNotFoundif either was missing. This adds opt-in support fordecoding through that gap.
Changes
EmptyRepresentableprotocol: conformAttributes/Relationshipsto it, andResourcefalls back to
.emptywhen the corresponding key is absent, instead of throwing. (Malformed-but-presentdata still throws as before.)
@ResourceWrapperauto-synthesizes this conformance whenever every attribute/relationshipproperty is
Optional— the common case needs no extra annotation. Applied independently toattributes vs. relationships;
BodyDefinitionis excluded.Tradeoffs
"defaults-to-
[]" semantics added here).Swift.Optional<T>(only
T?/Optional<T>) — a pre-existing limitation in a shared macro helper, not aregression, and not worth touching for this rare spelling.