Is it possible to error when a required field is missing after unmarshalling?

[rdbo]

I wanted to know if it's possible to error when a required field was not found during the unmarshall.
Example:

type MyConfig struct {
	DatabaseUrl string `toml:"database_url,required"`
}

var MyConfig cfg
if err := toml.Unmarshall(configFileContent, &cfg), err != nil {
	// Handle missing required field error, or any other error
}

I don't know if this is possible, but it is easier to check a single error than checking if each individual field doesn't contain an invalid value. If it isn't possible, I say it would be a nice addition.

[pelletier]

Really sorry I missed this question!

There is no notion of required field in go-toml. In the spirit of keeping go-toml minimal, I think this feature is better implemented outside the library, for example: https://github.com/go-playground/validator. If you want to answer the question "is this value present in the toml document?" you have three options that come to mind:

• Unmarshal into a struct, and use a package like validator to check its result.
• Unmarshal into an interface{} and walk its value to see what was in the file.
• Use the unstable/parser API to iterate over each key of the document.

[rdbo]

For reference, I ended up doing my own validator by unmarshalling the fields as pointers, then checking if the pointers are nil for fields marked as required. Not sure if that's a good option, but worked for me