Cannot deserialize value of type `java.math.BigDecimal` from String ".05": not a valid representation

[EAlf91]

Search before asking

• I searched in the issues and found nothing similar.

Describe the bug

We faced an issue with the newest release of jackson 2.17 while deserializing BigDecimals from JsonInput with a string value of the format ".f" e.g. {"value":".03"}

When deserializing using a standard ObjectMapper this exception is thrown.

com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.math.BigDecimal` from String ".05": not a valid representation
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); line: 1, column: 10] (through reference chain: TestDTO["value"])

	at com.fasterxml.jackson.databind.exc.InvalidFormatException.from(InvalidFormatException.java:67)
	at com.fasterxml.jackson.databind.DeserializationContext.weirdStringException(DeserializationContext.java:1958)
	at com.fasterxml.jackson.databind.DeserializationContext.handleWeirdStringValue(DeserializationContext.java:1245)
	at com.fasterxml.jackson.databind.deser.std.NumberDeserializers$BigDecimalDeserializer.deserialize(NumberDeserializers.java:1058)
	at com.fasterxml.jackson.databind.deser.std.NumberDeserializers$BigDecimalDeserializer.deserialize(NumberDeserializers.java:990)
	at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:310)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:177)
	at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:342)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4905)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3848)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3816)
	at BigDecimalTest.shouldDeserializeBigDecimalFromJacksonDataBind(BigDecimalTest.java:27)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)

Version Information

2.17

Reproduction

I created a small project with two unit tests, one using NumberInput.parseBigDecimal from jackson-core which is running fine as well as test which is deserializing the same value from a json input.

@Test
public void shouldDeserializeBigDecimalFromJacksonCore() {
    BigDecimal actualFromJacksonCore = NumberInput.parseBigDecimal(".05", true);
    assertEquals(expected, actualFromJacksonCore);
}

@Test
public void shouldDeserializeBigDecimalFromJacksonDataBind() throws JsonProcessingException {
    BigDecimal actualFromJacksonDataBind = mapper.readValue("""{"value":".05"}""", TestDTO.class).getValue();
    assertEquals(expected, actualFromJacksonDataBind);
}

https://github.com/EAlf91/jackson-issue

Output from the tests:

Expected behavior

I would expect jackson-databind to be able to deserialize the given input as both jackson-core and FastDoubleParser which jackson is relying on both can handle it.

The Changelog also does only mention an enum related change which seems unrelated to the behaviour described in this issue.

Additional context

One of the changes here might have caused this behaviour:
ce9c629

[pjfanning]

Does this work with Jackson 2.16? I can see a change in Jackson 2.17 that may have changed the behaviour.

[EAlf91]

@pjfanning hey, yes 2.16 is perfectly fine. I linked the prevalidation change in the "Additional Context" section of this issue. There's a comment explicitly mentioning 2.17