Première table de cours pour ajouter un champ ouvert, tapez Boolean; rake db: migrate Erreur d'opération?

Question

class AddOpenAttributeToCourses < ActiveRecord::Migration 
    def change 
    add_column :courses, :open, :boolean 
    change_column_default(:courses, :open, {:from=>true, :to=>false}) 
    end 
end 

!!!!! puis l'opération !!!!!!

rake db:migrate 
== 20161126133112 AddOpenAttributeToCourses: migrating ======================== 
-- add_column(:courses, :open, :boolean) 
    -> 0.1047s 
-- change_column_default(:courses, :open, {:from=>true, :to=>false}) 
rake aborted! 
StandardError: An error has occurred, this and all later migrations canceled: 

PG::InvalidTextRepresentation: ERROR: invalid input syntax for type boolean: "--- 
:from: true 
:to: false 
" 
: ALTER TABLE "courses" ALTER COLUMN "open" SET DEFAULT '--- 
:from: true 
:to: false 
' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/postgresql/database_statements.rb:155:in `async_exec' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/postgresql/database_statements.rb:155:in `block in execute' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/abstract_adapter.rb:472:in `block in log' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5.2/lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/abstract_adapter.rb:466:in `log' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/postgresql/database_statements.rb:154:in `execute' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/postgresql/schema_statements.rb:455:in `change_column_default' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:665:in `block in method_missing' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:634:in `block in say_with_time' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:634:in `say_with_time' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:654:in `method_missing' 
/home/ubuntu/workspace/db/migrate/20161126133112_add_open_attribute_to_courses.rb:4:in `change' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:608:in `exec_migration' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:592:in `block (2 levels) in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:591:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:292:in `with_connection' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:590:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:768:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:998:in `block in execute_migration_in_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:1044:in `block in ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `block in transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/abstract/transaction.rb:184:in `within_new_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/transactions.rb:220:in `transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:1044:in `ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:997:in `execute_migration_in_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:959:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:955:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:955:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:823:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/migration.rb:801:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/tasks/database_tasks.rb:137:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/rake-11.2.2/exe/rake:27:in `<top (required)>' 
ActiveRecord::StatementInvalid: PG::InvalidTextRepresentation: ERROR: invalid input syntax for type boolean: "--- 
:from: true 
:to: false 
" 

Answer 1

Vous pouvez créer la colonne et définir une valeur par défaut dans une ligne:

add_column :courses, :open, :boolean, default: true 

Je ne sais pas exactement pourquoi vous obtenez cette erreur. Peut-être que c'est parce que vous dites "changer la valeur par défaut de faux à vrai" mais la valeur par défaut était pas faux, en fait c'était nil.

Answer 2

Vous essayez d'utiliser le Rails5 arguments to change_column_default:

change_column_default (nom_table, nom_colonne, default_or_changes)
[...] Passing un hachage contenant :from et :to fera ce changement réversible migration:

change_column_default(:posts, :state, from: nil, to: "draft") 

avec Rails4:

change_column_default (nom_table, nom_colonne, par défaut)
Définit une nouvelle valeur par défaut pour une colonne: [...]

La substance drôle regardant vous voyez dans le SQL:

--- 
:from: true 
:to: false 

est la version YAML de votre { :from => true, :to => false } Ruby Hash BTW.

Vous devez utiliser up et down séparés méthodes et version simplifiée de change_column_default avec Rails4:

def up 
    change_column_default(:courses, :open, false) 
end 
def down 
    change_column_default(:courses, :open, true) 
end 

ou tout simplement définir la valeur par défaut lorsque vous créez la colonne:

class AddOpenAttributeToCourses < ActiveRecord::Migration 
    def change 
    add_column :courses, :open, :boolean, :default => false 
    end 
end 

BTW, puisque vous n'a pas spécifié un :default lorsque vous avez ajouté la colonne, il aurait une valeur par défaut de null, pas true.