NoMethodError:用于#<Array> (Rails 5)的未定义方法`value_for_database‘

Question

我有一个全新的Rails 5项目，当我试图运行迁移时，它会抛出错误。

(我使用PostgreSQL 9.4在Raspberry上运行Ruby2.2.4，但当我第一次尝试使用SQLite运行迁移时，会弹出相同的错误消息。)

到目前为止，我唯一得到的迁移是非常基本的：

class CreateAuthors < ActiveRecord::Migration[5.0]
  def change
    create_table :authors do |t|
      t.string :username
      t.timestamps
    end
  end
end

这将在我运行rake db:migrate时产生以下输出。

pi@raspberrypi:~/projects/gnn $ rake db:migrate
== 20160915091621 CreateAuthors: migrating ====================================
-- create_table(:authors, {})
   -> 0.0283s
== 20160915091621 CreateAuthors: migrated (0.0287s) ===========================

rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

undefined method `value_for_database' for #<Array:0x2a10470>
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `block in exec_no_cache'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `each'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `map'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `exec_no_cache'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:587:in `execute_and_clear'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:103:in `exec_query'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:135:in `exec_insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:124:in `insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/query_cache.rb:14:in `insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/relation.rb:65:in `insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:554:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/counter_cache.rb:128:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/locking/optimistic.rb:75:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/attribute_methods/dirty.rb:123:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:302:in `block in _create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:97:in `__run_callbacks__'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:750:in `_run_create_callbacks'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:302:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/timestamp.rb:68:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:534:in `create_or_update'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:298:in `block in create_or_update'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:97:in `__run_callbacks__'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:750:in `_run_save_callbacks'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:298:in `create_or_update'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:152:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/validations.rb:50:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/attribute_methods/dirty.rb:30:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:324:in `block in save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:395:in `block in with_transaction_returning_status'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:230:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:211:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:392:in `with_transaction_returning_status'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:324:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/suppressor.rb:45:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:51:in `create!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1247:in `record_version_state_after_migrating'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1212:in `block in execute_migration_in_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1279:in `block in ddl_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `block in transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/transaction.rb:189:in `within_new_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:211:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1279:in `ddl_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1210:in `execute_migration_in_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1183:in `block in migrate_without_lock'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1182:in `each'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1182:in `migrate_without_lock'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1131:in `block in migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1298:in `with_advisory_lock'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1131:in `migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1005:in `up'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:983:in `migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/tasks/database_tasks.rb:161:in `migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/railties/databases.rake:58:in `block (2 levels) in <top (required)>'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/rake-11.2.2/exe/rake:27:in `<top (required)>'
NoMethodError: undefined method `value_for_database' for #<Array:0x2a10470>
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `block in exec_no_cache'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `each'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `map'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:597:in `exec_no_cache'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:587:in `execute_and_clear'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:103:in `exec_query'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:135:in `exec_insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:124:in `insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/query_cache.rb:14:in `insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/relation.rb:65:in `insert'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:554:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/counter_cache.rb:128:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/locking/optimistic.rb:75:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/attribute_methods/dirty.rb:123:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:302:in `block in _create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:97:in `__run_callbacks__'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:750:in `_run_create_callbacks'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:302:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/timestamp.rb:68:in `_create_record'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:534:in `create_or_update'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:298:in `block in create_or_update'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:97:in `__run_callbacks__'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:750:in `_run_save_callbacks'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/callbacks.rb:298:in `create_or_update'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:152:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/validations.rb:50:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/attribute_methods/dirty.rb:30:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:324:in `block in save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:395:in `block in with_transaction_returning_status'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:230:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:211:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:392:in `with_transaction_returning_status'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:324:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/suppressor.rb:45:in `save!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:51:in `create!'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1247:in `record_version_state_after_migrating'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1212:in `block in execute_migration_in_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1279:in `block in ddl_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `block in transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/transaction.rb:189:in `within_new_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:211:in `transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1279:in `ddl_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1210:in `execute_migration_in_transaction'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1183:in `block in migrate_without_lock'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1182:in `each'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1182:in `migrate_without_lock'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1131:in `block in migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1298:in `with_advisory_lock'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1131:in `migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:1005:in `up'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/migration.rb:983:in `migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/tasks/database_tasks.rb:161:in `migrate'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/activerecord-5.0.0.1/lib/active_record/railties/databases.rake:58:in `block (2 levels) in <top (required)>'
/home/pi/.rvm/gems/ruby-2.2.4@gnn/gems/rake-11.2.2/exe/rake:27:in `<top (required)>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

编辑：也许值得说rake db:create运行得很好。

这也是我的database.yml文件，以防我错过了一些东西(我对PostgreSQL非常熟悉)

default: &default
  adapter: postgresql
  encoding: unicode
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
  <<: *default
  database: gnn_dev
  username: gnn
  password: Lorem123
  host: localhost
  port: 5432

Answer 1

我在发展过程中也遇到过同样的问题。找到了原因。

在我的例子中，我添加了一个新的gem 'imgurapi'，它将'to_hash‘添加到数组对象中。

class Array # :nodoc:
  # Skipped code 

  def to_hash # :nodoc:
    inject({}) { |hsh, (k,v)| hsh[k] = v  ; hsh }
  end unless method_defined?(:to_hash)
end

因此，调用gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:135:in 'exec_insert'中的代码gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:135:in 'exec_insert'按原因将binds变量从binds转换为哈希类型，这一点在这里很好地描述了https://makandracards.com/makandra/36013-heads-up-ruby-implicitly-converts-a-hash-to-keyword-arguments。因此，我们有错误，因为这种转换是意外的。

溶液

找到定义数组'to_hash‘方法的gem，并去掉这个定义。祝好运!

Answer 2

从第一行中删除5.0。

​

class CreateAuthors < ActiveRecord::Migration 
  def change
    create_table :authors do |t|
      t.string :username
      t.timestamps
    end
  end
end

​

谢谢

Answer 3

从第一行删除5.0

重新启动服务器并运行rake :migrate。

也许这会对你有帮助。