Class: Ramen::Metadata::PrimaryKey

Inherits:
RowDataGateway show all
Defined in:
lib/ramen/metadata/primary_key.rb

Overview

PrimaryKey contains meta-data about the primary key for a Table. The attributes are database engine specific.

Only primary_key_name is required by Ramen. See RowDataGateway for more information.

PrimaryKey also contains a collection of PrimaryKeyColumn objects. These are accessable by the column attribute.

See Database for a description of how PrimaryKey fits in the Ramen collection hierarchy.

Links: readme.txt; source

Instance Method Summary collapse

Methods inherited from RowDataGateway

add_attributes, compare

Constructor Details

#initialize(record, database) ⇒ PrimaryKey

:section: Internal Methods The following methods are for Ramen’s internal use. They are not intended for clients of Ramen to use.



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# File 'lib/ramen/metadata/primary_key.rb', line 50

def initialize( record, database )
  super( record, database )
  @columns = Ramen::RamenHash.new( PrimaryKeyColumn, 'column' )
end

Instance Method Details

#<=>(other) ⇒ Object

Comparison, returns -1,0,+1, compares primary_key_name



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# File 'lib/ramen/metadata/primary_key.rb', line 25

def <=> other
  Ramen::RowDataGateway.compare( primary_key_name, other )
end

#add_column(obj) ⇒ Object

add_column( obj ) #=> obj

Adds the column to this table. Throws a RamenError if the obj is not a ForeignKeyColumn.



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# File 'lib/ramen/metadata/primary_key.rb', line 67

def add_column( obj )
  @columns.add( obj )
end

#add_to(database) ⇒ Object

add_to( database )

Add self to the given database. (Choosing Message; Double Dispatch pattern) (Kent Beck. Smalltalk Best Practices Patterns. Perntice Hall PTR, Upper Saddle River, NJ 1997)



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# File 'lib/ramen/metadata/primary_key.rb', line 59

def add_to( database )
  database.schema[ self.table_schema ].table[ self.table_name ].set_primary_key( self )
end

#column ⇒ Object

column() #=> RamenHash reference

This attribute provides access to a RamenHash of all PrimaryKeyColumn objects in the PrimaryKey. The hash is indexed by column_name and column_id (if available).

usage:

require 'lib/ramen'
db = Ramen.create( configuration )
schema = db.schema['HumanResources']
table = schema.table['Employee']
pk = table.pk['PK_Employee_EmployeeID']
pk_column = pk.column['EmployeeID'] #=> #<Ramen::PrimaryKeyColumn ...



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# File 'lib/ramen/metadata/primary_key.rb', line 42

def column
  @columns
end