ModelMapper: apply rule to all fields of type

Question

I have a DTO with a lot of String fields (some are of other types).
When mapping objects into objects of another similar class, I need to apply a transformation to all fields of type String, in this case - trim().

So, I have:

class MyDTO {
  String name;
  String type;
  String company;
  String status;
  String whatever;
  ... (there are about 80 String fields)
  int someNumber;
  double otherNumber;
}

class DestinationDTO { // has just some fields of MyDTO
  String name;
  String type;
  String company;
  String whatever;
  int somenumber;
}

What I've tried:

Converter myConverter = c -> c.getSource().trim();
ModelMapper mm = new ModelMapper();
...
mm.typeMap(MyDTO.class, DestinationDTO.class)
  .addMappings(c -> c
      .using(myConverter)
      .map(MyDTO::getName, DestinationDTO::getName)
    ) // this applies to just one field, I need all String fields

Is there a way to specify all String fields of a class at once, instead of having to list them?

Tried searching the modelmapper.org docs, but all I see is configuring fields one by one.

Any ideas?

user_286934 · Answer

You can use converters to specify transformations from one type to another. The source and target type can be the same. Use the addConverter() method to add a general converter to the ModelMapper itself (rather than individually to a specific field). You can use it like this:

ModelMapper mm = new ModelMapper();
Converter myConverter = new AbstractConverter() {
    protected String convert(String source) {
        return source == null ? null : source.trim();
    }
};
mm.addConverter(myConverter);
mm.getConfiguration().setFieldMatchingEnabled(true);
MyDTO source = new MyDTO();
source.name = "   abc    	";
source.company = "
d   e  f  
";

DestinationDTO target = mm.map(source, DestinationDTO.class);
System.out.printf("Target.name: '%s'%n", target.name);
System.out.printf("Target.company: '%s'%n", target.company);

The output will be as expected:

Target.name: 'abc'
Target.company: 'd   e  f'

ModelMapper: apply rule to all fields of type

1 Answers