How to serialize to inline table vs. dotted table?

[maackle]

It seems that nested Tables are always serialized to dotted tables. e.g.:

let in_string = "[dependencies]\nhdk = { git = \"https://github.com/foo/bar\", branch = \"develop\" }"
let val = toml::from_str::<Value>(in_string)?;
println!("{:?}", toml::to_string(&val));

Even though the input string is an inline table, the output string uses a dotted table.

Is there no way to specify inline table when serializing?

[alexcrichton]

Currently this crate unfortunately doesn't support a lot of control over serialization and formatting, it just guarantees it emits some valid toml document, but not necessarily the prettiest

[samuelallan72]

Support for serializing inline tables would be great, because I suspect that is why I'm getting a ValueAfterTable error when serializing an object like:

#[derive(Deserialize, Serialize, Debug)]
#[serde(untagged)]
pub enum StringOrCmd {
    S(String),
    Cmd { cmd: Vec<String> },
}

#[derive(Deserialize, Serialize, Debug)]
pub struct BackendConfig {
    pub client_id: StringOrCmd,
    pub client_secret: StringOrCmd,
}

#[derive(Deserialize, Serialize, Debug)]
pub struct Config {
  backend: BackendConfig,
}

This should serialize to something like:

[backend]
client_id = { cmd = ["cat", ".clientid"] }
client_secret = "somesecret"

But becomes invalid TOML if not using inline table format:

[backend]

[backend.client_id]
cmd = ["cat", ".clientid"]

# oops!
client_secret = "somesecret"

The solution would be either supporting inline tables or using extra logic to ensure all literal types under a table are written out before any nested table types.

[DianaNites]

I just got hit by that ValueAfterTable problem and it'd be really nice if it worked.

I'm parsing perfectly valid toml and then can't write it out and thats no fun.

[samuelallan72]

Just for reference, cargo-edit uses toml_edit for parsing and writing cargo.toml files. Could be useful to see how they do it for anyone planning on implementing this for toml-rs.

[gabbifish]

I'm definitely on team "would love to have an inline table serialization option!" here :)

[deg4uss3r]

👍 Hitting this issue with cargo-outdated when trying to format Cargo.toml for cargo API. This causes interference with the namespaced-features feature.

[timabell]

There's a round-trip test of an inline table at https://github.com/alexcrichton/toml-rs/blob/60b874308e6792a73cc00517a60bbef60a12e3cc/test-suite/tests/valid/example-v0.4.0.toml#L34-L46= which makes me think this must be possible somehow with the right structures. Maybe it only works with the toml-rs internal types at the moment and not with types defined outside the toml-rs library.

[epage]

Maintenance of this crate has moved to the https://github.com/toml-rs/toml repo. As a heads up, we plan to move toml to be on top of toml_edit, see toml-rs/toml#340.

Closing this out. If this is still a problem, feel free to recreate this issue in the new repo.