Set global field naming policy for Json serialization

[audkar]

It would be convenient if we could set field naming policy for Json serialization globally.

I am aware that:

• It is possible to change single field naming via BuiltValueField. But it is cumbersome to do this for thousands of fields. And more often devs wants to set global policy instead of having fields with different naming conventions.
• It is possible to add additional serialization plugin for renaming. But that is not optimal from performance and logic side. Json plugin is responsible for converting dart objects to Json representation. It already does key name generation by looking into field name or using BuiltValueField value.

Every single json serializer I used with Java (GSON, Jackson, Moshi) have such functionality. So IMHO this is StandardJsonSerializer responsibility. WDYT?

related #144

[davidmorgan]

Sure, we could add support to StandardJsonSerializer. Did you have an idea for what the API would look like?

[audkar]

We could get some inspiration from existing tools like Gson naming policy and add fieldNamingPolicy to constructor :)

<...>
  ..addPlugin(StandardJsonSerializer(
      fieldNamingPolicy: FieldNamingPolicy.upperCamelCase,
  ))

---

Implementation can have constructor which uses Enum directly:

StandardJsonPlugin({this.discriminator = r'$', this.valueKey = '', this.fieldNamingPolicy = FieldNamingPolicy.identity});

Or create factory constructor which could create SomeNamingObject from FieldNamingPolicy Enum for concern separation and test-ability or smth else...

[danielgomezrico]

This is supported on dart package json_serializable with a config from pubspec.yml field_rename: snake but I believe that is better to have this setup in code like the idea of the FieldNamingPolicy.

https://pub.dev/packages/json_serializable#build-configuration

[davidmorgan]

Thanks--this definitely makes sense--will likely be a little while before it lands, though, as we'll need to wait for general release of null safety in the SDK before we can release the next built_value.