Micronaut POJO deserialisation error message when the format is invalid or type throws error - deserialization

Question

When providing the incorrect format of a field for a request to my application if the type throws an error then the error message returned by micronaut is vague.
E.G two scenarios
public class fakeClass {
#NotNull
private String fakeName;
}
if my request is {"fakeName": ""}
then the response, correctly, would be something like
{
"violations": [
{
"field": "create.fakeClass.fakeName",
"message": "must not be blank"
}
],
"type": "https://zalando.github.io/problem/constraint-violation",
"title": "Constraint Violation",
"status": 400 }
But lets say my class looks like this:
public class fakeClass {
#Format("yyyy-MM-dd")
private LocalDate exampeDate;
}
With an invalid date or incorrect format of {"exampleDate": 202222--01-01} or {"exampleDate": 2022/01/01}
Then the error message is
{
"type": "about:blank",
"parameters": {
"path": "/project"
},
"status": 400,
"detail": "Required argument [fakeClass fakeClass] not specified"
}
Is there a simple way to provide more information to the error message to make it clear why the request failed for an invalid format or type like #NotNull or #NotBlank?

Answer 1

The problem here is not Micronaut but your payloads. The examples you mentioned are invalid JSON documents.
For example this on here is invalid, since the value is not a number nor a string.
{
"exampleDate": 202222--01-01
}
this would be the a valid variant
{
"exampleDate": "202222--01-01"
}
Make sure you send the date as a String. In your case this is expected to be valid.
{
"exampleDate": "2022-11-01"
}
In general it is recommended to send date using the ISO-8601 format, which you did (yyyy-MM-dd). Furthermore I recommend to apply a global configuration rather than using on each POJO a #Format("yyyy-MM-dd") annotation.
jackson:
dateFormat: yyyyMMdd
timeZone: UTC
serializationInclusion: NON_NULL
serialization:
writeDatesAsTimestamps: false

Answer 2

#Format("yyyy-MM-dd") is a formatter not a Constraint.
You can use #Pattern(<regex>). There is also date specific ones like #Past, #PastOrPresent, #Futureand #FutureOrPresent.