[API Doc](https://docs.rs/diesel_sqltype_enum_pg/0.1.0/diesel-sqltype-enum-pg/)
# Diesel Enum Derivation for `FromSql` and `ToSql`
This procedural macro simplifies the process of generating Diesel `FromSql` and `ToSql` instances for enums with a specific `SqlType`. It is designed for use with Diesel and Postgres, utilizing `ToString` and `FromStr` traits as the base for conversion. This macro generates the necessary boilerplate code for handling enum conversions between Rust and SQL.
## Table of Contents
- [Usage](#usage)
- [Example](#example)
- [Enums and SqlTypes](#enums-and-sqltypes)
- [Dependencies](#dependencies)
---
## Usage
To use this procedural macro, you'll need to add the `enum_diesel_macros` crate to your project's dependencies in `Cargo.toml`. You can then derive the necessary implementations for your enums. Below is an example of how to use the `FromToSql` macro:
```rust
#[derive(Debug, PartialEq, EnumString, Display, FromToSql)]
#[fromtosql(sql_type = MyEntityEnumSqlType)]
enum MyEntityEnum {
#[strum(serialize = "ONE")]
EnumOne,
#[strum(serialize = "TWO")]
EnumTwo,
}
```
Make sure to import the required dependencies and modules as shown in the example.
## Example
Here's a step-by-step example of how to use the `FromToSql` macro to generate Diesel `FromSql` and `ToSql` instances for your **enum**:
1. Define your custom SQL type using Diesel's `SqlType` and annotate it with diesel attributes:
```rust
pub mod schema {
pub mod sql_types {
#[derive(diesel::sql_types::SqlType)]
#[diesel(postgres_type(name = "myentittyenumsqltype", schema = "myschema"))]
pub struct MyEntityEnumSqlType;
}
}
```
2. Import the necessary Diesel and procedural macro dependencies:
```rust
#[derive(Debug, PartialEq, EnumString, Display, FromToSql)]
#[fromtosql(sql_type = MyEntityEnumSqlType)]
enum MyEntityEnum {
#[strum(serialize = "ONE")]
EnumOne,
#[strum(serialize = "TWO")]
EnumTwo,
}
```
3. Now, you can use your `MyEntityEnum` enum seamlessly with Diesel queries.
## Enums and SqlTypes
The key to using this macro is to ensure that you have a corresponding `SqlType` defined for your **enum**. In this example, `MyEntityEnumSqlType` represents the SQL type for the `MyEntityEnum` **enum**. This `SqlType` is generated in Diesel schemas and serves as the companion **enum** to `MyEntityEnum`.
Ensure that your **enum** also implements either the `FromStr` or `EnumString` trait, which is crucial for parsing the **enum** from SQL values.
## Dependencies
To use this procedural macro, make sure to include the following dependencies in your `Cargo.toml`:
```toml
[dependencies]
diesel = { version = "2.1", features = ["postgres"] }
strum = "0.25"
strum_macros = "0.25"
diesel-sqltype-enum-pg = "0.1.0"
```