Schema

Schema migration classes must extend the Base Schema class class to run SQL DDL operations as code.

You can create a new schema migration by running the node ace make:migration command.

import BaseSchema from '@ioc:Adonis/Lucid/Schema'

class UserSchema extends BaseSchema {
}

Lifecycle methods

Every schema class has the following lifecycle methods that get executed when you run or rollback the migrations.

up

The up method is used to define the operations to be executed when running the node ace migration:run command. In this method, you always perform constructive operations like create a table or alter a table.

class UserSchema extends BaseSchema {
  public async up() {
  }
}

down

The down method is supposed to undo the actions executed by the up method. You need to use the equivalent API for running the undo actions manually.

For example, If the up method creates a new table using the createTable method, then the down method can use the dropTable method.

class UserSchema extends BaseSchema {
  public async up() {
    this.schema.createTable('users', () => {
    })
  }

  public async down() {
    this.schema.dropTable('users')
  }
}

Methods/Properties

Following is the list of methods and properties available on the schema class.

now

The now method is a helper to set the default value to the CURRENT_TIMESTAMP.

table.timestamp('created_at').defaultTo(this.now())

raw

Creates a raw query to be used for running DDL statements.

class UserSchema extends BaseSchema {
  public up() {
    this.defer(async () => {
      await this.raw('CREATE EXTENSION IF NOT EXISTS "uuid-ossp"')
    })
  }
}

defer

The defer method allows you to wrap custom database operations inside a defer block. Deferring actions is required for the following reasons.

• Ensure that your custom actions are executed in the right sequence
• Ensure your actions are not executed when migrations are running in dry-run mode.

public async up() {
  this.defer(async () => {
    // Only executed when not running in dry-run mode
    await this.db.from('users')
  })
}

debug

A property to enable/disable queries debugging for the given schema class. By default, the debugging is inherited from the query client used by the schema class.

class UserSchema extends BaseSchema {
  public debug = false
}

disableTransactions

A property to enable/disable wrapping database queries inside a transaction. The transactions are enabled by default. All the statements inside a given migration file are wrapped inside a single transaction.

class UserSchema extends BaseSchema {
  public disableTransactions = true
}

schema

Returns a reference to the schema builder . The property is getter and returns a new instance of schema builder on every access.

class UserSchema extends BaseSchema {
  public up() {
    // every access call returns a new instance
    console.log(this.schema !== this.schema)
  }
}

execUp

The method is invoked internally during the migration process to execute the user-defined up method. You should never call this method manually.

execDown

The method is invoked internally during the migration process to execute the user-defined down method. You should never call this method manually.

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