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Setting up the database

In order to compile the project, a database needs to be set-up. That's because SQLx accesses the database at compile time to make sure your SQL queries are correct.

To set up the database, download the SQLx CLI and run sqlx database setup. This command will create the database and its tables by applying the migration files in migrations/.

Most SQLx CLI commands require the DATABASE_URL environment variable to be set to the database URL, for example sqlite:database.sqlite (where sqlite: is the protocol and database.sqlite the actual filename). A convenient way to supply this information to SQLx is to create a .env file which SQLx automatically detects and reads:

DATABASE_URL=sqlite:database.sqlite

Running the example

# Note: due to a bug in SQLx (https://github.com/launchbadge/sqlx/issues/3099),
# you have to provide the full path to `DATABASE_URL` when compiling.
# Once the bug is fixed, you can omit `DATABASE_URL=...` and let SQLx read the `.env` file.
DATABASE_URL=sqlite:examples/e16_sqlite_database/database.sqlite DISCORD_TOKEN=... cargo run

Interact with the bot via ~todo list, ~todo add and ~todo remove.

What are migrations

In SQLx, migrations are SQL query files that update the database schema. Most SQLx project have at least one migration file, often called initial_migration, which sets up tables initially.

If you need to modify the database schema in the future, call sqlx migrate add "MIGRATION NAME" and write the migration queries into the newly created .sql file in migrations/.

Make it easy to host your bot

Normally, users have to download and install SQLx CLI in order to compile your bot. Remember: SQLx accesses the database at compile time. However, you can enable building in "offline mode": https://github.com/launchbadge/sqlx/tree/master/sqlx-cli#enable-building-in-offline-mode-with-query. That way, your bot will work out-of-the-box with cargo run.

Note that users still have to set SQLX_OFFLINE to true even if sqlx-data.json is present.

Tip: create a git pre-commit hook which executes cargo sqlx prepare for you before every commit. See the pre-commit file for an example. Copy the file into .git/hooks to install the pre-commit hook.

Using SQLx

SQLx's GitHub repository explains a lot about SQLx, like the difference between query! and query_as!. Please follow the links to learn more: