toml-scaffold

Generate commented TOML configuration scaffold files from Rust structs and values.

Features

Preserve doc comments as TOML comments
Preserve field order in generated TOML
Support for common types: primitives, Option, HashMap, Vec, nested structs and serde_json::Value
Customizable formatting with #[format] attribute

Installation

Add the following dependencies to your Cargo.toml:

[dependencies]
serde = { version = "1", features = ["derive"] }
schemars = "1"
toml-scaffold = "0.4"

Usage

Basic Example

use schemars::JsonSchema;
use serde::Serialize;
use toml_scaffold::TomlScaffold;

/// Server configuration
#[derive(Serialize, JsonSchema, TomlScaffold)]
struct Config {
    /// Server host address
    host: String,
    /// Server port
    port: u16,
}

fn main() {
    let config = Config {
        host: "localhost".to_string(),
        port: 8080,
    };
    let scaffold = config.to_scaffold().unwrap();
    println!("{}", scaffold);
}

Output:

# Server configuration

# Server host address
host = "localhost"
# Server port
port = 8080

Custom Formatting

Use #[format = "..."] to control how fields are rendered:

use schemars::JsonSchema;
use serde::Serialize;
use toml_scaffold::TomlScaffold;

#[derive(Serialize, JsonSchema, TomlScaffold)]
struct Database {
    host: String,
    port: u16,
}

#[derive(Serialize, JsonSchema, TomlScaffold)]
struct Config {
    name: String,
    
    /// Inline table format
    #[format = "inline"]
    database: Database,
    
    /// Dotted keys format
    #[format = "dotted"]
    server: Database,
    
    /// Child dotted format - keep [section], flatten children
    #[format = "*dotted"]
    settings: serde_json::Value,
}

Output:

name = "myapp"
database = { host = "localhost", port = 5432 }
server.host = "0.0.0.0"
server.port = 8080

[settings]
key1 = 123
nested.key2 = 456

Format Options:

"inline" - Inline table: { key = value }
"dotted" - Flatten one level: field.key = value
"dotted-nested" - Recursively flatten: field.key.subkey = value
"*dotted" - Keep [field] section, flatten children
"*dotted-nested" - Keep [field] section, recursively flatten children
"multiline" - Force multiline array format

toml-scaffold 0.4.0