ConvertUsing

Call convertUsing() and pass in a Converter to map the configured property with the Converter#convert method.

export interface Converter<TheSource, TheResult> {
    convert(source: TheSource): TheResult;
}

Converter can be used to extract common logic where we want to map one data type to another. Converter can be reused across different Mappings in the application. For example, we might have a dateToStringConverter

export const dateToStringConverter: Converter<Date, string> = {
    convert(source) {
        // maybe handle validation, additional parsing, or format here
        return source.toDateString();
    },
};

createMap(
    mapper,
    User,
    UserDto,
    forMember(
        (destination) => destination.birthday,
        convertUsing(dateToStringConverter, (source) => source.birthday)
    )
);

tip

If we have simple logic, we can use Type Converter to also map from one data type to another on the Mapping level instead of convertUsing on the property level.

convertUsing() sets the TransformationType to TransformationType.ConvertUsing