Module diesel::migrations

Provides functions for maintaining database schema.

A database migration always provides procedures to update the schema, as well as to revert itself. Diesel's migrations are versioned, and run in order. Diesel also takes care of tracking which migrations have already been run automatically. Your migrations don't need to be idempotent, as Diesel will ensure no migration is run twice unless it has been reverted.

Migrations should be placed in a /migrations directory at the root of your project (the same directory as Cargo.toml). When any of these functions are run, Diesel will search for the migrations directory in the current directory and its parents, stopping when it finds the directory containing Cargo.toml.

Individual migrations should be a folder containing exactly two files, up.sql and down.sql. up.sql will be used to run the migration, while down.sql will be used for reverting it. The folder itself should have the structure {version}_{migration_name}. It is recommended that you use the timestamp of creation for the version.

Example

# Directory Structure
- 20151219180527_create_users
    - up.sql
    - down.sql
- 20160107082941_create_posts
    - up.sql
    - down.sql

-- 20151219180527_create_users/up.sql
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  name VARCHAR NOT NULL,
  hair_color VARCHAR
);

-- 20151219180527_create_users/down.sql
DROP TABLE users;

-- 20160107082941_create_posts/up.sql
CREATE TABLE posts (
  id SERIAL PRIMARY KEY,
  user_id INTEGER NOT NULL,
  title VARCHAR NOT NULL,
  body TEXT
);

-- 20160107082941_create_posts/down.sql
DROP TABLE posts;

Enums

MigrationError
RunMigrationsError

Traits

Migration
MigrationConnection	A connection which can be passed to the migration methods. This exists only to wrap up some constraints which are meant to hold for all connections. This trait will go away at some point in the future. Any Diesel connection should be useable where this trait is required.

Functions

find_migrations_directory	Returns the directory containing migrations. Will look at for $PWD/migrations. If it is not found, it will search the parents of the current directory, until it reaches the root directory. Returns MigrationError::MigrationDirectoryNotFound if no directory is found.
migration_from
revert_latest_migration	Reverts the last migration that was run. Returns the version that was reverted. Returns an Err if no migrations have ever been run.
run_migrations	Run all pending migrations in the given list. Apps should likely be calling run_pending_migrations or run_pending_migrations_in_directory instead.
run_pending_migrations	Runs all migrations that have not yet been run. This function will print all progress to stdout. This function will return an Err if some error occurs reading the migrations, or if any migration fails to run. Each migration is run in its own transaction, so some migrations may be committed, even if a later migration fails to run.
search_for_migrations_directory	Searches for the migrations directory relative to the given path. See find_migrations_directory for more details.