Having knowledges about missing/unexpected properties in a config file at deserialization time

[Djaytan]

Hello,

After some searches I didn't find my answer.

Let's take directly an example. I have the following simple config file with a valid content:

hostname: "example.com"
port: 1234
isSslEnabled: true

But I want that any unexpected properties must lead to a failure like this is the case for the following content:

hostname: "example.com"
port: 1234
isSslEnabled: true
unexpectedField: test

To fail on missing fields, I know it exists the method ConfigurationNode#require but which seems usable only when creating a custom TypeSerializer.

What about when having a class annotated with @ConfigSerializable like for the following simplified one:

@ConfigSerializable
// Lombok annotations...
public final class HostValidatingProperties
    extends ValidatingConvertibleProperties<HostProperties> {

  private String hostname;
  private int port;
  private boolean isSslEnabled;

  // Other methods...
}

Is there a way to configure the ObjectMapper/TypeSerializer to reach the wanted behavior? Even having just a way to detect that a ConfigurationNode has unexpected/missing fields would be enough without speaking about failing / sending warning logs or whatever else.

Even if we can find solutions for missing fields, this isn't the same story for unexpected ones.

[Djaytan]

For missing fields, @Required annotation add the sought constraint. By taking back the example provided in the question, we obtain this result:

@ConfigSerializable
// Lombok annotations...
public final class HostValidatingProperties
    extends ValidatingConvertibleProperties<HostProperties> {

  @Required
  private String hostname;

  @Required
  private int port;

  @Required
  private boolean isSslEnabled;

  // Other methods...
}

Following test pass now:

class DbmsHostValidatingPropertiesTest {

    /* Other tests */

    @DisplayName("With missing content")
    @Test
    void withMissingContent_shouldThrowSerializationException() {
      // Given
      String yamlFileName = "whenDeserializing_withMissingPortField.yml";
      Path yamlFile = /* ... */; // Retrieve the empty YAML file somewhere

      // When
      ThrowingCallable throwingCallable = () -> TestYamlDeserializerHelper.deserialize(yamlFile,
        DbmsHostValidatingProperties.class);

      // Then
      assertThatThrownBy(throwingCallable).isInstanceOf(SerializationException.class);
    }
}

However, I didn't found any trivial way to add a constraint for unexpected fields by reading Configurate's source code. Maybe with additional searches something could be found, but finally I realized that this isn't really important in fact. So, I decided to abandon this idea. Having the possibility to add a constraint about required fields is enough for me and works.