Module: Og::Evolution

Defined in:
lib/og/store/sql/evolution.rb

Overview

– Implement Og’s automatic schema evolution features. Add schema evolution related methods to SqlStore. ++

Instance Method Summary collapse

Instance Method Details

#add_sql_field(klass, a, anno) ⇒ Object Also known as: add_sql_column

– Override if needed in the actual Adapter implementation. ++



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# File 'lib/og/store/sql/evolution.rb', line 14

def add_sql_field(klass, a, anno)
  Logger.info "Adding field '#{a}' to '#{klass.table}'"
  query "ALTER TABLE #{klass.table} ADD COLUMN #{field_sql_for_attribute a, anno}"
end

#evolve_schema(klass) ⇒ Object

Evolve the schema (table in sql stores) for the given class. Compares the fields in the database schema with the serializable attributes of the given class and tries to fix mismatches by adding are droping columns.

Evolution options

  • :evolve_schema => :add (only add, dont remove columns)

  • :evolve_schema => :full (add and delete columns)

  • :evolve_schema => :warn (only emit warnings, DEFAULT_

  • :evolve_schema => false (no evolution)

Example

Og.setup(

..
:evolve_schema => :full
..

)



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# File 'lib/og/store/sql/evolution.rb', line 59

def evolve_schema(klass)
  return unless @options[:evolve_schema]

  sql_fields = create_field_map(klass).keys
  attrs = serializable_attributes_for_class(klass)

  # Add new fields to the table.
  
  for field in attrs
    unless sql_fields.include? field
      unless @options[:evolve_schema] == :warn
        add_sql_field klass, field, klass.ann(field)
      else
        Logger.warn "Missing field '#{field}' on table '#{klass.table}'!"
      end
    end
  end
    
  # Remove obsolete fields from the table.
 
  for field in sql_fields
    unless attrs.include? field
      if @options[:evolve_schema] == :full 
        remove_sql_field klass, field
      else
        Logger.warn "Obsolete field '#{field}' found on table '#{klass.table}'!"
      end
    end
  end   
end

#remove_sql_field(klass, a) ⇒ Object

– Override if needed in the actual Adapter implementation. ++



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# File 'lib/og/store/sql/evolution.rb', line 24

def remove_sql_field(klass, a)
  Logger.info "Removing field '#{a}' from '#{klass.table}'"
  query "ALTER TABLE #{klass.table} DROP COLUMN #{a}"
end

#rename_schema(old_schema, new_schema) ⇒ Object

Renames the schema (table in sql stores) for the given class.

Input

  • new_schema = the new schema (Class or table name)

  • old_schema = the old schema (Class or table name)

Example

store.rename_schema(TicketArticle, Ticket::Article)



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# File 'lib/og/store/sql/evolution.rb', line 102

def rename_schema(old_schema, new_schema)
  if old_schema.is_a? Class
    old_schema = table(old_schema)
  end

  if new_schema.is_a? Class
    new_schema = table(new_schema)
  end

  rename_sql_table(old_schema, new_schema)     
end

#rename_sql_table(_old, _new) ⇒ Object

– Override if needed in the actual Adapter implementation. ++



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# File 'lib/og/store/sql/evolution.rb', line 34

def rename_sql_table(_old, _new)
  Logger.info "Rename table '#{_old}' to '#{_new}'"
  query "ALTER TABLE #{_old} RENAME #{_new}"
end