Class: RStore::BaseDB

Inherits:
Object show all
Defined in:
lib/rstore/base_db.rb

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.db_classes ⇒ Hash{Symbol=>BaseDB} (readonly)

A Hash holding subclasses of RStore::BaseDB

Examples:

class CompanyDB < RStore::BaseDB
  info #...
end

class MyDB < RStore::BaseDB
  info #...
end

RStore::BaseDB.db_classes
#=> {:company=>companyDB, :my=>MyDB}

Returns:

  • (Hash{Symbol=>BaseDB}) —

    All subclasses of RStore::BaseDB defined in the current namespace. Subclasses are added automatically via self.inherited.



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# File 'lib/rstore/base_db.rb', line 23

def db_classes
  @db_classes
end

Class Method Details

.connect {|db| ... } ⇒ void

Note:

To be called when defining a subclass of RStore::BaseDB

This method returns an undefined value.

Uses the connection info from info to connect to the database.

Examples:

class CompanyDB < RStore::BaseDB
  info(adapter: 'mysql',
       host: 'localhost',
       user: 'root',
       password: 'xxx')
end

class DataTable < RStore::BaseTable
  create do
    primary_key :id, :allow_null => false
    String      :col1
    Integer     :col2
    Float       :col3
  end
end

name = DataTable.name

#Either
DB = CompanyDB.connect
DB.drop_table(name)
DB.disconnect

#Or
CompanyDB.connect do |db|
  db.drop_table(name)
end

Yield Parameters:

  • db (Sequel::Database) —

    The opened Sequel Database object, which is closed when the block exits.



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# File 'lib/rstore/base_db.rb', line 103

def self.connect &block
  Sequel.connect(@connection_info, &block)
end

.info(options) ⇒ void

Note:

To be called when defining a subclass of RStore::BaseDB

Define the database connection. Accepts the same one arity parameters as [Sequel.connect](sequel.rubyforge.org/rdoc/files/doc/opening_databases_rdoc.html)

Examples:

# Using a connection string
class CompanyDB < RStore::BaseDB
  info('postgres://user:password@localhost/blog')
end

# Using an options hash
class CompanyDB < RStore::BaseDB
  info(adapter: 'mysql',
       host: 'localhost',
       user: 'root',
       password: 'xxx')
end

This method returns an undefined value.

Parameters:

  • connection_info (String, Hash) —

    Either a connection string such as _postgres://user:password@localhost/blog_, or a Hash with the following options:

Options Hash (options):

  • :adapter (String) —

    The SQL database used, such as mysql or postgres

  • :host (String) —

    Example: ‘localhost’

  • :user (String)
  • :password (String)
  • :database (String) —

    The database name. You don’t need to provide this option, as its value will be inferred from the class name.



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# File 'lib/rstore/base_db.rb', line 58

def self.info hash_or_string
  # self = CompanyDB

  class << self
    # self = #<Class:CompanyDB>
    attr_reader :connection_info
  end

  # Instance variables always belong to self.
  @connection_info = hash_or_string.is_a?(Hash) ? hash_or_string.merge(:database => self.name.to_s): hash_or_string
end

.inherited(subclass) ⇒ Object 



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# File 'lib/rstore/base_db.rb', line 29

def self.inherited subclass
  BaseDB.db_classes[subclass.name] = subclass
end

.name ⇒ Symbol

Returns The lower-case class name without the DB postfix.

Examples:

class CompanyDB < RStore::BaseDB
  info('postgres://user:password@localhost/blog')
end

CompanyDB.name
#=> :company

Returns:

  • (Symbol) —

    The lower-case class name without the DB postfix



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# File 'lib/rstore/base_db.rb', line 117

def self.name
  super.gsub!(/DB/,'').downcase.to_sym
end