modelmapper can't map from a NULL or empty String to LocalDate

[felipealvesgnu]

I'm trying to map from a NULL json string field and I'm getting:

1) Converter org.modelmapper.module.jsr310.ToTemporalConverter@e3441d9 
      failed to convert java.lang.String to java.time.LocalDate.

1 error] with root cause
                 java.lang.NullPointerException: null
...

and when with an empty string field I get:

1) Converter org.modelmapper.module.jsr310.ToTemporalConverter@25b6e24d 
       failed to convert java.lang.String to java.time.LocalDate.

1 error] with root cause
                 java.time.format.DateTimeParseException: Text '' could not be parsed at index 0
	...

[internetstaff]

We're hitting this too, which renders the module useless to us.

Is there a simple universal work-around we're not aware of?

If not, is this by design or should it be fixed?

[felipealvesgnu]

in the beginning I tried this:

    @Bean
     public ModelMapper modelMapper() {
         ModelMapper modelMapper = new ModelMapper();

          Jsr310ModuleConfig config = Jsr310ModuleConfig.builder()
                 .dateTimePattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'") // default is yyyy-MM-dd HH:mm:ss
                 .datePattern("yyyy-MM-dd")
                 .build();
         modelMapper.registerModule(new Jsr310Module(config));

        return modelMapper;
     }

With that code, you can format the pattern you receive the data, from your front-end.
So I started to had some problems with empty data that was coming from my Json, because of that I removed this module, and stayed just with modelmapper core and simply made a change in my DTO replacing date attributes from String to Localdate in DTOs and JPA entities.
Have you tried it?

[internetstaff]

In my case I don't control the data coming in, and it's protobuf, so it has optional blank strings for dates that I simply need to skip.

[felipealvesgnu]

You can take this piece of code, that uses skip as an example:

modelMapper.typeMap(ActivityDTO.class, Person.class).addMappings(map -> map.skip(Person::setId));

In that case, I'm letting the mapper know that I don't want to set Activity.id attribute into Person.id, telling it to skip the mapping on that part.
Do you got it?

[internetstaff]

Yes, I can skip individual fields, but I have dozens and dozens of fields to deal with, so a universal solution would be preferable.

Of course, it's easy enough to setup a custom blank-skipping converter for LocalDate/LocalDateTime, and that's what I've done, but that does mean this module is useless. :)

[felipealvesgnu]

Have you tried this, in your config class? It will ignore all incoming null attributes:

@Configuration
public class ModelMapperConfig {

    @Bean
    public ModelMapper modelMapper() {
        ModelMapper modelMapper = new ModelMapper();
        modelMapper.getConfiguration().setSkipNullEnabled(true);

        return modelMapper;
    }
}

[internetstaff]

@felipealvesgnu again, thanks, but in our case the incoming fields are empty strings.