我想尝试gem coles_tree为我的家谱数据库构建树。我在Windows 7盒子上安装了Ruby MRI 2.3.0下的宝石。依赖项的版本在下面的errorlog中。
$ gem install closure_tree
Fetching: with_advisory_lock-3.0.0.gem (100%)
Successfully installed with_advisory_lock-3.0.0
Fetching: closure_tree-6.2.0.gem (100%)
Successfully installed closure_tree-6.2.0
2 gems installed
当我尝试最简约的代码失败时，我想是因为我不使用铁轨，也不要做迁移，我又假定创建表tag_hierachies
我的问题是：我可以在没有铁轨的情况下使用这个宝石吗？
require 'active_record'
require 'closure_tree'
ActiveRecord::Base.establish_connection(
:adapter => "sqlite3",
:database => "sample.db"
)
if !ActiveRecord::Base.connection.table_exists?('tags')
ActiveRecord::Schema.define do
create_table :tags do |table|
table.column :name, :string
table.column :parent_id, :integer
end
end
end
class Tag < ActiveRecord::Base
has_closure_tree
end
grandparent = Tag.create(name: 'Grandparent')
给出
d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/sqlite3_adapter.rb:513:in `table_structure': Could not find table 'tag_hierarchies' (ActiveRecord::StatementInvalid)
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/sqlite3_adapter.rb:387:in `columns'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/schema_cache.rb:43:in `columns'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/attributes.rb:93:in `columns'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/attributes.rb:98:in `columns_hash'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/inheritance.rb:205:in `subclass_from_attributes?'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/inheritance.rb:54:in `new'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/persistence.rb:50:in `create!'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/closure_tree-6.2.0/lib/closure_tree/hierarchy_maintenance.rb:65:in `block in rebuild!'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/closure_tree-6.2.0/lib/closure_tree/support.rb:108:in `block (2 levels) in with_advisory_lock'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in `transaction'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:220:in `transaction'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/closure_tree-6.2.0/lib/closure_tree/support.rb:108:in `block in with_advisory_lock'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/with_advisory_lock-3.0.0/lib/with_advisory_lock/base.rb:77:in `yield_with_lock'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/with_advisory_lock-3.0.0/lib/with_advisory_lock/base.rb:65:in `yield_with_lock_and_timeout'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/with_advisory_lock-3.0.0/lib/with_advisory_lock/base.rb:48:in `with_advisory_lock_if_needed'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/with_advisory_lock-3.0.0/lib/with_advisory_lock/concern.rb:16:in `with_advisory_lock_result'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/with_advisory_lock-3.0.0/lib/with_advisory_lock/concern.rb:10:in `with_advisory_lock'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/closure_tree-6.2.0/lib/closure_tree/support.rb:107:in `with_advisory_lock'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/closure_tree-6.2.0/lib/closure_tree/hierarchy_maintenance.rb:63:in `rebuild!'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/closure_tree-6.2.0/lib/closure_tree/hierarchy_maintenance.rb:39:in `_ct_after_save'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb:432:in `block in make_lambda'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb:228:in `block in halting_and_conditional'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb:506:in `block in call'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb:506:in `each'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb:506:in `call'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb:92:in `__run_callbacks__'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb:778:in `_run_save_callbacks'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/callbacks.rb:302:in `create_or_update'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/persistence.rb:120:in `save'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/validations.rb:37:in `save'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/attribute_methods/dirty.rb:21:in `save'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:286:in `block (2 levels) in save'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:351:in `block in with_transaction_returning_status'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `block in transaction'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/transaction.rb:184:in `within_new_transaction'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `transaction'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:220:in `transaction'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:348:in `with_transaction_returning_status'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:286:in `block in save'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:301:in `rollback_active_record_state!'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/transactions.rb:285:in `save'
from d:/Ruby/lib/ruby/gems/2.3.0/gems/activerecord-4.2.6/lib/active_record/persistence.rb:34:in `create'
from C:/Users/Gebruiker/BoxSync/ruby_werk/acts_as_tree/closure_tree.rb:22:in `<main>'
似乎读书中的安装说明仅考虑了轨道。但是，它确实告诉您，您还需要另一个表（除当前的tags表之外），名称为tag_hierarchies。
在铁轨中，该表的产生似乎是安装步骤的一部分；链接文档中的步骤5
因此，您应该创建具有以下内容的tag_hierarchies表，就表结构而言，这就是rails g closure_tree:migration tag生成的。请参阅create_hierarchies_table.rb.erb，因为您可能还想添加索引，如此链接文件所示。
因此，将您的脚本更新到以下内容对我的预期工作：
require 'active_record'
require 'closure_tree'
ActiveRecord::Base.establish_connection(
:adapter => "sqlite3",
:database => "sample.db"
)
if !ActiveRecord::Base.connection.data_source_exists?('tags')
ActiveRecord::Schema.define do
create_table :tags do |table|
table.column :name, :string
table.column :parent_id, :integer
end
end
end
# You also need a corresponding model's table name followed by "_hierarchies" table.
#
# Migration created based on
# `https://github.com/mceachen/closure_tree/blob/master/lib/generators/closure_tree/templates/create_hierarchies_table.rb.erb`
if !ActiveRecord::Base.connection.data_source_exists?(:tag_hierarchies)
ActiveRecord::Schema.define do
create_table :tag_hierarchies do |table|
table.integer :ancestor_id, null: false
table.integer :descendant_id, null: false
table.integer :generations, null: false
end
end
end
class Tag < ActiveRecord::Base
has_closure_tree
end
grandparent = Tag.create(name: 'Grandparent')
grandparent.children.create(name: 'Father')
grandparent.children.create(name: 'Uncle')