value for multipleOf

[AleksanderBialik]

Hey!
Is there a way to properly format the value for multipleOf for @Schema(multipleOf = 0.01)?
It generates schema with "multipleOf" : 0.0100000000000000055511151231257827021181583404541015625

[CarstenWickner]

Hi @AleksanderBialik,

Generally, yes. In the schema generator, the multipleOf value is treated as a BigDecimal, i.e., you can explicitly set the scale (number of decimal digits).
Unfortunately, on the swagger @Schema annotation, the multipleOf parameter is of type double which has this precision problem.

Short-term, you could basically re-implement the configuration with your desired precision:

jsonschema-generator/jsonschema-module-swagger-2/src/main/java/com/github/victools/jsonschema/module/swagger2/Swagger2Module.java

Line 92 in baea9b6

configPart.withNumberMultipleOfResolver(this::resolveMultipleOf);

jsonschema-generator/jsonschema-module-swagger-2/src/main/java/com/github/victools/jsonschema/module/swagger2/Swagger2Module.java

Lines 304 to 308 in baea9b6

	protected BigDecimal resolveMultipleOf(MemberScope<?, ?> member) {
	return this.getSchemaAnnotationValue(member, Schema::multipleOf, multipleOf -> multipleOf != 0)
	.map(BigDecimal::new)
	.orElse(null);
	}

Mid-term, we could assume a certain maximum precision (let's say: rounded to 10 decimal digits) and then cut off trailing zeros. That would cover your use case at least.

[AleksanderBialik]

Hi @CarstenWickner,
Thanks for reply!
Actually I just did that what you recommended with re-implementing the resolveMultipleOf method and used BigDecimal::valueOf. This solution persists the precision set in the @Schema annotation.
Could the BigDecimal::valueOf actually replace the current solution in the Swagger2Module.java?

[CarstenWickner]

I didn't know BigDecimal::valueOf behaves differently in that way.
That is a great observation. I'll adapt that immediately in #365.