Modelmapper to convert from String to LocalDate

问题

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".

回答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

来源：https://stackoverflow.com/questions/39454492/modelmapper-to-convert-from-string-to-localdate

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Spring

modelmapper