sqlx-database

SQLx Database Error Handling Example

Demonstrates comprehensive database error handling patterns using SQLx and masterror.

Features

• Connection Error Handling - Database connection failures
• Query Error Mapping - SQL errors to domain errors
• Constraint Violation Handling - Unique/foreign key violations
• Transaction Error Patterns - Rollback and commit handling
• Row Not Found - Handling missing data gracefully

Running

cd examples/sqlx-database
cargo run

This example uses an in-memory SQLite database, so no external setup is required.

Error Scenarios

Connection Errors

// Mapped to AppError::Database
sqlx::SqlitePool::connect("sqlite::memory:").await?

Row Not Found

// Mapped to AppError::NotFound
sqlx::query_as::<_, User>("SELECT * FROM users WHERE id = ?")
    .bind(id)
    .fetch_one(&pool)
    .await?

Unique Constraint Violation

// Mapped to AppError::Conflict
sqlx::query("INSERT INTO users (id, email) VALUES (?, ?)")
    .bind(id)
    .bind(email)
    .execute(&pool)
    .await?

Transaction Handling

let mut tx = pool.begin().await?;

// Operations...

tx.commit().await?; // Or tx.rollback() on error

Error Conversion

masterror automatically converts SQLx errors:

SQLx Error	AppError Kind	HTTP Status
RowNotFound	NotFound	404
UniqueViolation	Conflict	409
ForeignKeyViolation	Conflict	409
ConnectionError	Database	500
Other database errors	Database	500

Testing

cargo test

License

MIT