[StackOverflow/rust] trouble getting sqlx #[derive(sqlx::Type)] to work with a rust enum using MySQL/MariaDB

### ROOT CAUSE The issue arises because SQLx requires explicit configuration to handle custom Rust enums as database types, especially with MySQL/MariaDB. By default, SQLx doesn't automatically map Rust enums to database ENUM types, leading to deserialization errors. The enum must be explicitly registered with SQLx using `#[derive(sqlx::Type)]` and `#[sqlx(type_name = "...")]`. --- ### CODE FIX 1. **Derive `sqlx::Type` and specify the database type name**: ```rust use sqlx::Type; #[derive(sqlx::Type)] #[sqlx(type_name = "status_enum")] // Match your DB ENUM name enum Status { Active, Inactive, Pending, } ``` 2. **Ensure the database ENUM exists**: Create the ENUM in your MySQL/MariaDB database: ```sql CREATE ENUM status_enum AS ENUM('Active', 'Inactive', 'Pending'); ``` 3. **Use the enum in a struct (if needed)**: ```rust #[derive(sqlx::FromRow)] struct User { id: i32, status: Status, // Works with the derived Type } ``` 4. **Handle dynamic values** (if the enum is used in queries): ```rust let param: Status = Status::Active; let row = sqlx::query_as!(User, "SELECT * FROM users WHERE status = ?", param) .fetch_one(&pool) .await?; ``` **Key Notes**: - The `type_name` must match the database ENUM name exactly (case-sensitive). - Use `#[try_into]` if deserializing from database values: ```rust impl TryFrom for Status { type Error = sqlx::Error; fn try_from(value: sqlx::types::Enum) -> Result { // Map database values to Rust enum match value.as_str()? { "Active" => Ok(Status::Active), // ... other mappings } } } ``` This ensures SQLx properly serializes/deserializes the enum between Rust and MySQL/MariaDB.