Loading structs with mixed field tags into koanf

[Alexander Bakker]

Thanks for koanf! It's great.

I hope you don't mind me opening an issue to ask a question. I have a Config struct with a few fields:

type Config struct {
        Dir   string     `koanf:"dir"`
        Creds Creds      `koanf:"creds"`
	HTTP  HTTP       `koanf:"http"`
	Log   zap.Config `koanf:"log"`
}

All of the top-level fields in the struct have a koanf tag, and most of the child structs also have fields with that tag. However, one of those structs is of a type that I don't control and thus doesn't have koanf tags for its fields: zap.Config. It does have tags for JSON and YAML though.

I tell koanf to load an instance of that struct with a couple of defaults as follows:

k.Load(structs.Provider(&defaultConfig, "koanf"), nil)

This works, but the problem is that this results in a mixed-case confMap. All of the keys are lower case, except for the zap.Config ones. I understand why this happens, but I'd like to find a way to make everything consistent without having to pull a copy of zap.Config into my codebase and adding koanf tags to all of its fields.

I suppose I could rename all of the koanf tags in my own structs to yaml to fix the issue, but this workaround falls apart if in the future there's another type I don't control that only has json tags. What is the best way to approach this? Is there a way to tell koanf that it should look for a different tag for a certain path? I couldn't immediately find a way do that.

[Kailash Nadh]

Sorry, missed this issue! You can specify and tag on struct field. Instead of koanf, you can use json.

k.UnmarshalWithConf("", &data, koanf.UnmarshalConf{Tag: "json"})