Expose preference key to Converter

The change from Adapter to Converter interface (#75) breaks some functionality use cases where serializing/deserializing from shared preferences depends on the preference key. For example, I have an EncryptedPreferenceAdapter that worked as follows with the previous Adapter interface:

    @Override
    public Optional<T> get(@NonNull String key, @NonNull SharedPreferences preferences) {
            final String serialized = preferences.getString(key, null);
            if (serialized == null)
                return Optional.empty();
            final String decrypted = Obfuscator.decryptFromStorage(key, serialized);
            return Optional.ofNullable(decrypted);
    }

    @Override
    public void set(@NonNull String key, @NonNull Optional<T> optionalValue, @NonNull SharedPreferences.Editor editor) {
            if (optionalValue.isPresent()) {
                editor.putString(key, Obfuscator.encryptForStorage(key, optionalValue.get()));
            }
            else {
                editor.putString(key, null);
            }
    }

Can Converters be updated to provide the preference key? Or can adapters be resurrected since there may be apps out in the wild that have adapters serializing to non-string types?

[m4xp1]

I think the converter interface is very good. And your case is quite specific. Because I think that for you it will be a good option that something like this:

  public class KeyConverter implements Preference.Converter<String> {

        private final String key;

        public KeyConverter(String key) {
            this.key = key;
        }

        @Override
        public @NonNull String deserialize(@NonNull String serialized) {
            return Obfuscator.decryptFromStorage(key, serialized);
        }

        @Override
        public @NonNull String serialize(@NonNull String value) {
            return Obfuscator.encryptForStorage(key, value);
        }
    }

What say?

[f2prateek]

Gonna close this out, don’t have any plans to change this soon and I think there are a few options to make this work if needed (e.g. https://github.com/f2prateek/rx-preferences/issues/100#issuecomment-342676597).