Interface ValueDecoder<Data>

  • Type Parameters:
    Data - The codegen or primitive type that this decodes a Value to.
    Functional Interface:
    This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

    public interface ValueDecoder<Data>
    A converter from the encoded form of a Daml value, represented by Value, to the codegen-decoded form, represented by Data.

    Every codegen class for a template, record, or variant includes a valueDecoder method that produces one of these. If the data type has type parameters, valueDecoder has arguments that correspond to ValueDecoders for those type arguments. For primitive types that are not code-generated, see PrimitiveValueDecoders.

     // given template 'Foo', and encoded payload 'Value fooValue'
     Foo foo = Foo.valueDecoder().decode(fooValue);
     // given Daml datatypes 'Bar a b' and 'Baz',
     // and encoded 'Bar' 'Value barValue'
     Bar<Baz, Long> bar = Bar.valueDecoder(
         Baz.valueDecoder(), PrimitiveValueDecoders.fromInt64)
     Bar<List<Baz>, Map<Long, String>> barWithAggregates = Bar.valueDecoder(
    • Method Detail

      • fromFunction

        static <A> ValueDecoder<A> fromFunction​(java.util.function.Function<Value,​A> fromValue)
        since Daml 2.5.0; it is only used in deprecated fromValue method of all generated data class