Modelmapper to convert from String to LocalDate

Question

My DTO is having date field in String format. My entity is having date as LocalDate. Currently I am skipping it from map and then later manually explicitly setting it (String to Date and vis-versa).

is it possible to convert it automatically? I tried Converter inside spring bean but it gives me lot of compile errors (type Converter does not take parameters, does not override convert method - also lot of error for convert() as well).

@Bean
public ModelMapper studentModelMapper() {
....    
    Converter<String, LocalDate> toStringDate = new AbstractConverter<String, LocalDate>() {
        protected String convert(String source) {
            return source == null ? null : new LocalDate(source);
        }
    };
....
}

I am not very familiar with modelmapper. Any help is greatly appreciated.

As suggested I tried with LocalDate for DTO but the problem is when I send this entity at front (REST call) I get following JSON.

"dateOfBirth": {
   "year": 1972,
   "month": "JANUARY",
   "monthValue": 1,
   "dayOfMonth": 4,
   "dayOfWeek": "TUESDAY",
   "era": "CE",
   "dayOfYear": 4,
   "leapYear": true,
   "chronology": {
      "id": "ISO",
      "calendarType": "iso8601"
   }
}

My front end developer need "YYYY-MM-DD".

Answer 1

If you want to convert to LocalDate you need to create a Provider otherwise ModelMappercannot instantiate LocalDate because it doesn't have a public default constructor.

Use this configuration and it will work:

 ModelMapper modelmapper = new ModelMapper();

    Provider<LocalDate> localDateProvider = new AbstractProvider<LocalDate>() {
        @Override
        public LocalDate get() {
            return LocalDate.now();
        }
    };

    Converter<String, LocalDate> toStringDate = new AbstractConverter<String, LocalDate>() {
        @Override
        protected LocalDate convert(String source) {
            DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy-MM-dd");
            LocalDate localDate = LocalDate.parse(source, format);
            return localDate;
        }
    };


    modelmapper.createTypeMap(String.class, LocalDate.class);
    modelmapper.addConverter(toStringDate);
    modelmapper.getTypeMap(String.class, LocalDate.class).setProvider(localDateProvider);

Test output:

 String dateTest = "2000-09-27";
 LocalDate dateConverted = modelmapper.map(dateTest, LocalDate.class);

 System.out.println(dateConverted.toString()); //Output = 2000-09-27

Answer 2

I also use ModelMapper 2.3.5 for my project and had a similar issue. The use of the ModelMapper related project https://github.com/modelmapper/modelmapper-module-java8/ helped me a lot.

It provides two modules that one can add to ModelMapper configuration by providing the following maven dependencies to your project :

<!-- https://mvnrepository.com/artifact/com.github.chhsiao90/modelmapper-module-java8-datatypes -->
<dependency>
    <groupId>com.github.chhsiao90</groupId>
    <artifactId>modelmapper-module-java8-datatypes</artifactId>
    <version>1.1.0</version>
</dependency>

<!-- https://mvnrepository.com/artifact/com.github.chhsiao90/modelmapper-module-jsr310 -->
<dependency>
    <groupId>com.github.chhsiao90</groupId>
    <artifactId>modelmapper-module-jsr310</artifactId>
    <version>1.1.0</version>
</dependency>

Then the ModelMapper configuration should add

modelMapper.registerModule(new Jsr310Module());
modelMapper.registerModule(new Jdk8Module());

Hope this can help

Answer 3

I am currently using ModelMapper 2.3.5 and the accepted solution does not work with me when I do ModelMapper.validate() for my mapping. See my related question.

I managed to get also validation working - surprisingly - by removing provider totally so only converter is used. So like:

modelmapper.addConverter(toStringDate);
modelmapper.getTypeMap(String.class, LocalDate.class); // no provider, maps ok with me still
modelmapper.validate();