Class: Hummingbird::Database

Inherits:
Object
  • Object
show all
Defined in:
lib/hummingbird/database.rb

Overview

Class to handle retrieving recorded migrations, as well as running new migrations and recording that they have been run.

Instance Method Summary collapse

Constructor Details

#initialize(connection_string, migrations_table) ⇒ Database

Returns a new instance of Database.

Parameters:

  • connection_string (String) —

    A / Sequel compatible connection string.

  • migrations_table (Symbol) —

    The name of the table used to keep track of migrations.



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# File 'lib/hummingbird/database.rb', line 12

def initialize(connection_string, migrations_table)
  @sequel_db                     = Sequel.connect(connection_string)
  @migrations_table_name         = migrations_table
  @prepared_run_migration_insert = nil
end

Instance Method Details

#already_run_migrations ⇒ Array<Hash{Symbol => String, Number}>

If the database has yet to be initialized with the migrations table, or if the migrations table has no recorded migrations, this will return an empty array.

If there are recorded migrations, this will return an array of hashes. Where the hashes have the following format:

{
  :migration_name => 'name/of/migration.sql',
  :run_on         => 1350683387
}

‘:migration_name` is the path of the migration file relative to the migrations directory. `:run_on` is the time the migration was run, as a unix epoch.

Returns:

  • (Array<Hash{Symbol => String, Number}>) —

    The list of migrations that have already been run, along with when they were run as a unix epoch.



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# File 'lib/hummingbird/database.rb', line 43

def already_run_migrations
  initialized? ? @sequel_db[@migrations_table_name].order(:run_on).to_a : []
end

#initialized? ⇒ true, false

Returns Whether or not the migrations table is present in the database.

Returns:

  • (true, false) —

    Whether or not the migrations table is present in the database.



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# File 'lib/hummingbird/database.rb', line 20

def initialized?
  @sequel_db.tables.include?(@migrations_table_name)
end

#run_migration(name, sql) ⇒ Object

Run the provided SQL in a transaction (provided the DB in question supports transactions). If the SQL successfully runs, then also record the migration in the migration table. The time recorded for the ‘run_on` of the migration is when the migration finished, not when it started.

Parameters:

  • name (String) —

    The name of the migration to run (as listed in the .plan file).

  • sql (String) —

    The SQL to run.



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# File 'lib/hummingbird/database.rb', line 57

def run_migration(name,sql)
  @prepared_run_migration_insert ||= @sequel_db[@migrations_table_name].prepare(:insert, :record_migration, migration_name: :$name, run_on: :$date)

  @sequel_db.transaction do
    @sequel_db.execute(sql)

    @prepared_run_migration_insert.call(name: name, date: DateTime.now.strftime('%s'))
  end

  true
end