This pull request introduces a new procedural macro, #[derive(ormlite::Enum)], to simplify the process of creating enums compatible with ormlite and SQLx. This macro automates the implementation of various traits for enums, such as:

• std::fmt::Display
• std::str::FromStr
• std::convert::TryFrom
• sqlx::Encode
• sqlx::Decode
• sqlx::Type

By deriving ormlite::Enum, developers can focus on defining their enums while ensuring they are ready to use with ormlite and SQLx without boilerplate code.

Example Usage

Before this feature, developers needed to manually implement traits for each enum:

use std::str::FromStr;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub enum MyEnum {
    VariantOne,
    VariantTwo,
}

impl std::fmt::Display for MyEnum { /* Implementation omitted */ }
impl std::str::FromStr for MyEnum { /* Implementation omitted */ }
// Other trait implementations...

With #[derive(ormlite::Enum)], the code becomes:

#[derive(ormlite::Enum)]
pub enum MyEnum {
    VariantOne,
    VariantTwo,
}

Features

• Automatically generates implementations for:
  • Display for string representations
  • FromStr for parsing strings into enum variants
  • SQLx traits (Encode, Decode, Type) for seamless database integration
• Supports snake_case conversion of enum variant names to strings.

Technical Details

Macro Implementation:

• Built using the proc-macro crate with dependencies on syn, quote, and proc-macro2.
• Ensures enums are safe and ergonomic for database operations.
• Internally, variants are converted to and from their snake_case string representations.

Impact

• Developer Experience: Reduces boilerplate code for ormlite/database-ready enums.
• Performance: Implements traits efficiently, matching manual implementations.

How to Use

1. Annotate enums with #[derive(ormlite::Enum)]:

   #[derive(ormlite::Enum)]
   pub enum Status {
      Active,
      Inactive,
   }

2. Use them in your ormlite::Models:

   #[derive(ormlite::Model)]
   struct Article {
      status: Status
   }

Next Steps

1. Create tests
2. Review the implementation and provide feedback.
3. Publish updated documentation for ormlite to include the new macro.
4. Tag a new release after merging.

Acknowledgments

Special thanks to everyone involved in designing and refining this crate! It's beautifully simple. 🎉

Closes #37