Удалите повторяющиеся столбцы в миграции рельсов

У меня есть копия Paperclip в моем приложении, после чего я удалил ее, и я хочу добавить ее обратно. Тем не менее, я получаю эту ошибку, когда я пытаюсь rake db:migrate:Удалите повторяющиеся столбцы в миграции рельсов

ActiveRecord::SchemaMigration Load (0.4ms) SELECT "schema_migrations".* FROM "schema_migrations" 
Migrating to AddAttachmentImageToPosts (20170115210207) 
    (0.3ms) BEGIN 
== 20170115210207 AddAttachmentImageToPosts: migrating ======================== 
-- change_table(:posts) 
    (0.9ms) ALTER TABLE "posts" ADD "image_file_name" character varying 
    (0.2ms) ROLLBACK 
rake aborted! 
StandardError: An error has occurred, this and all later migrations canceled: 

PG::DuplicateColumn: ERROR: column "image_file_name" of relation "posts" already exists 
: ALTER TABLE "posts" ADD "image_file_name" character varying 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/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/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/lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract_adapter.rb:466:in `log' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/connection_adapters/abstract/schema_statements.rb:393:in `add_column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql/schema_statements.rb:423:in `add_column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract/schema_definitions.rb:443:in `column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:54:in `block (2 levels) in attachment' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:52:in `each_pair' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:52:in `block in attachment' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:51:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:51:in `attachment' 
/home/ubuntu/workspace/db/migrate/20170115210207_add_attachment_image_to_posts.rb:4:in `block in up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract/schema_statements.rb:363:in `change_table' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:665:in `block in method_missing' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:634:in `say_with_time' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:654:in `method_missing' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:416:in `method_missing' 
/home/ubuntu/workspace/db/migrate/20170115210207_add_attachment_image_to_posts.rb:3:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:571:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:611:in `exec_migration' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:591:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:590:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:768:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:1044:in `block in ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/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/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/lib/active_record/transactions.rb:220:in `transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:1044:in `ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:997:in `execute_migration_in_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:959:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:955:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:955:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:823:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:801:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/tasks/database_tasks.rb:137:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/rake-12.0.0/exe/rake:27:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>' 
ActiveRecord::StatementInvalid: PG::DuplicateColumn: ERROR: column "image_file_name" of relation "posts" already exists 
: ALTER TABLE "posts" ADD "image_file_name" character varying 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/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/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/lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract_adapter.rb:466:in `log' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/connection_adapters/abstract/schema_statements.rb:393:in `add_column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql/schema_statements.rb:423:in `add_column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract/schema_definitions.rb:443:in `column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:54:in `block (2 levels) in attachment' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:52:in `each_pair' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:52:in `block in attachment' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:51:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:51:in `attachment' 
/home/ubuntu/workspace/db/migrate/20170115210207_add_attachment_image_to_posts.rb:4:in `block in up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract/schema_statements.rb:363:in `change_table' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:665:in `block in method_missing' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:634:in `say_with_time' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:654:in `method_missing' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:416:in `method_missing' 
/home/ubuntu/workspace/db/migrate/20170115210207_add_attachment_image_to_posts.rb:3:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:571:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:611:in `exec_migration' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:591:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:590:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:768:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:1044:in `block in ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/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/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/lib/active_record/transactions.rb:220:in `transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:1044:in `ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:997:in `execute_migration_in_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:959:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:955:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:955:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:823:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:801:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/tasks/database_tasks.rb:137:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/rake-12.0.0/exe/rake:27:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>' 
PG::DuplicateColumn: ERROR: column "image_file_name" of relation "posts" already exists 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/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/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/lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract_adapter.rb:466:in `log' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/connection_adapters/abstract/schema_statements.rb:393:in `add_column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql/schema_statements.rb:423:in `add_column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract/schema_definitions.rb:443:in `column' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:54:in `block (2 levels) in attachment' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:52:in `each_pair' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:52:in `block in attachment' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:51:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/paperclip-5.1.0/lib/paperclip/schema.rb:51:in `attachment' 
/home/ubuntu/workspace/db/migrate/20170115210207_add_attachment_image_to_posts.rb:4:in `block in up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract/schema_statements.rb:363:in `change_table' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:665:in `block in method_missing' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:634:in `say_with_time' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:654:in `method_missing' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:416:in `method_missing' 
/home/ubuntu/workspace/db/migrate/20170115210207_add_attachment_image_to_posts.rb:3:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:571:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:611:in `exec_migration' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:591:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:590:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:768:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/lib/active_record/migration.rb:1044:in `block in ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/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/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/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/lib/active_record/transactions.rb:220:in `transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:1044:in `ddl_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:997:in `execute_migration_in_transaction' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:959:in `block in migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:955:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:955:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:823:in `up' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/migration.rb:801:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/tasks/database_tasks.rb:137:in `migrate' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/rake-12.0.0/exe/rake:27:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>' 
Tasks: TOP => db:migrate 
(See full trace by running task with --trace)

Когда я побежал rails c это то, что я получил:

2.3.0 :001 > Post.column_names 
    => ["id", "title", "link", "description", "created_at", "updated_at", "user_id", "image_file_name", "image_content_type", "image_file_size", "image_updated_at", "cached_votes_total", "cached_votes_score", "cached_votes_up", "cached_votes_down", "cached_weighted_score", "cached_weighted_total", "cached_weighted_average", "image"]

Я знаю, что есть способ, чтобы удалить «image_file_name» но я не знаю, как это сделать в моем приложении. Я нашел несколько сообщений, похожих на мою проблему, но ничего не решило!

источник

2017-01-15 hekmat

Если у вас уже есть то поле, почему вы пытаетесь добавить его снова? –

Потому что, когда я удалил Paperclip раньше .. Я также удалил его миграцию – hekmat

прокомментируйте вашу модель, где вы добавили вложение, любую проверку ... и затем запустите файл миграции .. – Milind

Прежде всего, вы никогда не должны просто удалять миграцию. Если вы хотите удалить поле, вы должны создать для него новую миграцию.

У вас есть 2 варианта сейчас, или вы можете rake db:migration:reset, которые воссоздают всю вашу базу данных. Или вы можете прокомментировать содержимое этой последней миграции, запустите rake db:migrate, после чего вы можете раскомментировать его.

источник

2017-01-15 21:53:17

Я сделал второй вариант, и он запускал db: migrate. Однако, когда я пытаюсь загрузить изображение, я получаю эту «Post model missing required attr_accessor для« image_file_name » – hekmat

Должен ли я попробовать« rake db: migration: rest' now? – hekmat

Поскольку вы удалили миграцию для создания столбца, и если вы создаете перенос для ее удаления, это вызовет ошибку в другой среде (production), поскольку на первом месте не будет столбца.

Предполагая, что вы не развертываете миграцию на производство. Вы можете просто удалить столбец непосредственно в консоли базы данных.

пробег rails dbconsole

ALTER TABLE posts DROP COLUMN image_file_name;

источник

2017-01-15 22:03:44

Удалите повторяющиеся столбцы в миграции рельсов

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