com.fasterxml.jackson.databind.exc.MismatchedInputException 2.12 for Java record

Given:

Version information

version 2.11.3 which works properly openjdk 15.0.2

public record UserId(String raw){ }

jsonBody -> {"userId": "123456" }

ObjectMapper objectMapper = new ObjectMapper()
objectMapper.readValue(jsonBody, UserId.class)

noThrowsException()

Version information version 2.12 which not works properly openjdk 15.0.2

public record UserId(String raw){ }

jsonBody -> {"userId":  "123456" }

ObjectMapper objectMapper = new ObjectMapper()
objectMapper.readValue(jsonBody, UserId.class)

throws `Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `user.model.UserId` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('123456')

Version information version 2.12 which works properly openjdk 15.0.2

public record UserId(String raw) {
  @JsonCreator(mode = Mode.DELEGATING)
  public UserId {}
}

jsonBody -> {"userId": "123456" }

ObjectMapper objectMapper = new ObjectMapper()
objectMapper.readValue(jsonBody, UserId.class)

noThrowsException()

I am expecting Jackson to serialize String value to UserId record without using extra annotations as before. What can I do to have a pure approach? Maybe some global configuration on object mapper can be set?

[cowtowncoder]

@dkubicki Ok. So the reasoning for this change is two-fold:

1. Before 2.12, there was no planned support for Record types: they happen to mostly work by forcing setting of private fields, but this may not work with newer JDKs
2. With 2.12 support was added and since conceptually Records are collection of named properties, the default logic for all cases – 1, 2 or how many properties – is to use “Properties” style, expecting JSON Object, with matching name/value pairs. This differs from POJOs where logic for 1-argument case is much more complex and unpredictable

Although it would be possible to add a feature in ConstructorDetector to also allow overriding 1-argument Record case. But as of now, adding the annotation is way to go.

[dkubicki]

@cowtowncoder in my dependencies tree I have the 2.12.0 version

| | | | +--- com.fasterxml.jackson.core:jackson-core:2.10.3 -> 2.12.0 (*) | | | | +--- com.fasterxml.jackson.module:jackson-module-kotlin:2.10.3 -> 2.12.0 | | | | | +--- com.fasterxml.jackson.core:jackson-databind:2.12.0 (*) | | | | | +--- com.fasterxml.jackson.core:jackson-annotations:2.12.0 (*) | | | | | \--- com.fasterxml.jackson:jackson-bom:2.12.0 (

Thanks for the replay I gonna try your approach.

Update: I’ve tried 2.12.2 then I set up .constructorDetector(ConstructorDetector.USE_DELEGATING) Unfortunately, it doesn’t work. Still, I have to have @JsonCreator(mode = Mode.DELEGATING)