DoLess - Procedural Macro for Struct Mapping 🦀

DoLess is a Rust procedural macro that allows structs to be initialized from a HashMap<String, String>. It automatically maps field values, providing type-safe conversions.

🚀 Features

• 🏢 Auto-implements From<HashMap<String, String>> for structs.
• 🔄 Supports common Rust types (String, u8, u16, i32, f64, Option, Vec<T>, Vec<Option<T>>, etc.).
• ❌ Compile-time errors for unsupported types.
• ✅ Default values for missing fields.
• ⚙ Supports nested struct parsing with . notation.

🛆 Installation

Add DoLess to your Cargo.toml:

[dependencies]
doless = "0.3.0"

👺 Usage

Basic Struct Mapping

use doless::FromHashMap;
use std::collections::HashMap;

#[derive(FromHashMap, Debug, PartialEq)]
struct Car {
    model: String,
    year: u16,
}

fn main() {
    let mut data = HashMap::new();
    data.insert("model".to_string(), "GT-R".to_string());
    data.insert("year".to_string(), "2023".to_string());

    let car: Car = Car::from(data);
    println!("Car: Model = {}, Year = {}", car.model, car.year);
}

Nested Struct Support

use doless::FromHashMap;
use std::collections::HashMap;

#[derive(FromHashMap, Debug)]
struct Car {
    model: String,
    brand: String,
    number: u8,
    details: CarDetails,  // ✅ Nested Struct Support
}

#[derive(FromHashMap, Debug)]
struct CarDetails {
    name: String,
    description: String,
}

fn main() {
    let mut data = HashMap::new();
    data.insert("model".to_string(), "GT-R".to_string());
    data.insert("brand".to_string(), "Nissan".to_string());
    data.insert("number".to_string(), "8".to_string());

    // ✅ Nested Fields with Prefix Notation
    data.insert("details.name".to_string(), "Skyline".to_string());
    data.insert("details.description".to_string(), "Legendary Sports Car".to_string());

    let car: Car = Car::from(data);
    println!("{:?}", car);
}

Support for Vec<T> and Vec<Option<T>>

use doless::FromHashMap;
use std::collections::HashMap;

#[derive(FromHashMap, Debug)]
struct ItemCollection {
    items: Vec<String>,         // ✅ Supports Vec<String>
    numbers: Vec<u8>,           // ✅ Supports Vec<u8>
    optional_items: Vec<Option<String>>,  // ✅ Supports Vec<Option<T>>
}

fn main() {
    let mut data = HashMap::new();
    data.insert("items".to_string(), "apple, banana, orange".to_string());
    data.insert("numbers".to_string(), "1,2,3".to_string());
    data.insert("optional_items".to_string(), "apple,,orange".to_string()); // Empty string = None

    let collection: ItemCollection = ItemCollection::from(data);
    println!("{:?}", collection);
}

Expected Output

ItemCollection {
    items: ["apple", "banana", "orange"],
    numbers: [1, 2, 3],
    optional_items: [Some("apple"), None, Some("orange")],
}

🚀 Why Use DoLess?

• Simple & Lightweight — No runtime dependencies, just pure Rust.
• Declarative API — Uses procedural macros to generate efficient From<HashMap<String, String>> implementations.
• Type-Safe & Extensible — Ensures correct conversions and supports nesting.

⚙ Roadmap

• Basic primitive types mapping
• Nested struct support
• Vec<T> and Vec<Option<T>> support
• Custom conversion support
• Error handling improvements

Happy coding! ✨