Iterating over keys / values or serializing flattened view

[fabianfreyer]

I'm not sure how this would work with accessors, but I'm looking for an implementation that would allow me to get a flattened "view" of layered configuration with the ability to iterate over all config variables in each layer. Is there any chance this could fit into config-rs-ng's vision?

[matthiasbeyer]

Hm yes, I think that should be possible in general, but I don't quite understand the usecase for it... could you elaborate?

[fabianfreyer]

One use case I have is hooking up a layered config system with a template layer, e.g. Tera or Liquid. Those template systems usually require some context structure that contains all the values to be injected.

Another use case would be to render the flattened configuration to some serializeable format, e.g. JSON to be consumed by another application.

[matthiasbeyer]

One use case I have is hooking up a layered config system with a template layer, e.g. Tera or Liquid. Those template systems usually require some context structure that contains all the values to be injected.

I don't understand why you would need to iterate over the individual layers for this?

Another use case would be to render the flattened configuration to some serializeable format, e.g. JSON to be consumed by another application.

Serializing to a serde-compatible format is one of the things that has to be included in config-rs-ng!

[fabianfreyer]

I would not have to iterate over individual layers but over keys in the combined view. The problem is the a priori knowledge of the key names. Basically, I need to be able to put the results of the config into e.g. a serde_json::Value::Object, or some nested Hash/BTreeMap etc.

[matthiasbeyer]

Ah, yes... so that would mean you have some kind of Config objects and you want to serialize to serde_json::Value essentially?

[fabianfreyer]

Not sure what you mean by Config objects, but yes, the ability to serialize the flattened layers to serde_json::Value would be the goal. This would require being able to iterate over config keys/values as an intermediate step, which I believe also would provide value, e.g. to be able to log which values were customized over a "defaults" layer.

[matthiasbeyer]

This would require being able to iterate over config keys/values as an intermediate step, which I believe also would provide value

No, that would be included in config-rs-ng:

let json = Config::builder()
        .load(/* something */)
        .build()
        .unwrap()
        .serialize_to::<serde_json::Value>()
        .unwrap()

The above is pseudo-code, the interface may look completely different, but I think it shows what I mean: Loading different configurations into a layered object and then serializing that to some custom format (whereas "custom" can also be serde_json::Value or in fact any other serde-compatible format) should be included in config-rs-ng right from the get-go. No need to manually iterate over keys or such!