Package com.faunadb.client.types

Interface Codec<T>

  • Type Parameters:
    T - desired resulting type
    public interface Codec<T>
    Codec instances are used to convert a Value to a concrete type. There are pre-defined codecs for each FaunaDB primitive types. Each Codec implementation returns a Result instance for the conversion attempt. If the conversion attempt fails, the Result instance will contain an error message. Custom codecs can be created by implementing the Codec interface.

    Example:

    
 class User {
   static final Codec<User> USER_CODEC = new Codec<User>() {
     public Result<User> decode(Value value) {
       return Result.success(new User(
         value.at("username").to(String.class).getOrElse("<no name>"),
         value.at("password").to(String.class).getOrElse(null)
       ));
     }

     public Result<Value> encode(User user) {
       return Value.from(ImmutableMap.of(
         "username", user.username,
         "password", person.password
       ));
     }
   }

   final String username, password;

   Person(String username, String password) {
     this.firstName = firstName;
     this.lastName = lastName;
   }
 }

 //...
 Value result = client.query(getUser).get();
 Result<User> user = result.at("data").to(User.USER_CODEC);

    It is possible to annotate classes and let the internal framework encode/decode instances of the class automatically.

    Refer to the annotations FaunaField, FaunaConstructor, FaunaIgnore and FaunaEnum for more details.

    See Also:
    FaunaField, FaunaConstructor, FaunaEnum, FaunaIgnore, Encoder, Decoder, Language.Value(Object), Result