How to support custom member type?

[aj3423]

A struct contains big.Int, the code doesn't seem to work:

type Config struct {
	BigInt big.Int
	// lots of other members
}

func main() {
	cfg := &Config{
		BigInt: *big.NewInt(123),
	}

	str, _ := toml.Marshal(cfg)
	fmt.Println(string(str))
}

I see there is MarshalTOML() interface, but I'll have to implement marshal/unmarshal for all the other fields too, which are too many. Is there any way to support custom field like big.Int?

[pelletier]

This looks like a bug: I would expect the marshaler to use big.Int's TextMarshaler() method. Which version of go-toml are you using?

[aj3423]

I tried both v1 and v2, same problem.
github.com/pelletier/go-toml v1.9.5-0.20211018005641-352072d51afc
github.com/pelletier/go-toml/v2 v2.0.0-beta.4

[pelletier]

Thanks, created #678 to track the resolution.

[pelletier]

Should be fixed in v2 as of 2b3de62.

It was because big.Int actually implements TextMarshaler on *big.Int, and the go-toml encoder did not consider it when storing it as a value, as opposed to a pointer. Let me know if it works for you!

[aj3423]

@pelletier How to update to the v2 to the latest master? I tried write github.com/pelletier/go-toml/v2 master to "go.mod" then go mod tidy shows error:

github.com/pelletier/go-toml/v2: version "v2.0.0-20211018005641-352072d51afc" invalid: go.mod has non-.../v2 module path "github.com/pelletier/go-toml" (and .../v2/go.mod does not exist) at revision 352072d51afc

[pelletier]

For v2 the full module name is github.com/pelletier/go-toml/v2. You can use go get -u to update your go.mod to a specific commit:

$ go get -u github.com/pelletier/go-toml/v2@2b3de620e8cbec29bb050462bd074456247cd7b4

After this command, your go.mod should be automatically updated to contain a line like:

github.com/pelletier/go-toml/v2 v2.0.0-beta.4.0.20211124194349-2b3de620e8cb