Class: Trix51::Database

Inherits:
Trix51
  • Object
show all
Defined in:
lib/trix51db.rb

Overview

Class for managing a single Trix51 based database, allowing access to tables.

Constant Summary

Constants inherited from Trix51

KEY_JOIN, META_PREFIX, RECORD_PREFIX, SEQ_PREFIX

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Trix51

add_connection, add_helper, class_to_database, class_to_table, connections, create_helper_code, debug, defer_classref, defer_classref=, error, fatal, info, table_to_database, warn

Constructor Details

#initialize(*args) ⇒ Database

db = Trix51::Database.new( path: ‘./data’, database: ‘animals.t51’ )



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# File 'lib/trix51db.rb', line 182

def initialize( *args )

	@meta_prefix = Trix51::META_PREFIX
	@tables = {}
	@args = {
		:path => './trix',
		:database => 'database.db'
	}

	args.each { |key|
		key.each_pair { |k,v|
			@args[k] = v
		}
	}
	
	if not Dir.exist?( @args[:path] ) then
	  Dir.mkdir( @args[:path] )
	end
	
	# now create / open the dbm file
	begin
	  @dbm = GDBM.new( "#{@args[:path]}/#{@args[:database]}" )
	rescue => e
	    raise Trix51::DatabaseError, "Unable to open #{@args[:path]}/#{@args[:database]}: #{e.to_s}"
	end
	
	Trix51.add_connection( self )
	
	list = self.tables
	list.each do |tag|
	  tagref = self.get_table( tag )
	  Trix51.add_helper( tagref.classname, self, tagref )
	end

end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(methodid) ⇒ Object

:nodoc:

Raises:



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# File 'lib/trix51db.rb', line 313

def method_missing( methodid ) #:nodoc:
  if self.tables.include?( methodid ) then
    return self.get_table( methodid )
  end
  raise Trix51::NotFoundError, "Table #{methodid.to_s } does not exist"
end

Instance Attribute Details

#dbm ⇒ Object

Database accessor



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# File 'lib/trix51db.rb', line 326

def dbm
  @dbm
end

Instance Method Details

#close ⇒ Object

Close the database, cleaning up a persisting indexes to disk.



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# File 'lib/trix51db.rb', line 219

def close
  return if @dbm.closed?
  @tables.each_value do |tblref|
    tblref.indices_save( @args[:path] )
  end
  @dbm.close
end

#create_table(tablename, args, classname = 'Trix51::Tuple') ⇒ Object

animal = db.create_table(

:animal,
{

id: { datatype: ‘integer’, key: true, autoincrement: true }, species_id: { datatype: ‘integer’, required: true, indexed: true }, species: { datatype: ‘record’, source: :species_id, table: :species, dest: :id }, name: { datatype: ‘string’, required: true, unique: true }, created_date: { datatype: ‘datetime’, default: ‘#Time.new.to_s’ }, number_of_legs: { datatype: ‘integer’, default: 4 }, number_of_eyes: { datatype: ‘integer’, default: 2 }, legs_and_eyes: { datatype: ‘integer’, calculation: ‘number_of_legs + number_of_eyes’ }

  },
  'Animal'
)

Field types

Valid field types are ‘string’, ‘integer’, ‘datetime’, ‘float’, ‘boolean’, ‘record’, ‘resultset’

The ‘calculation:’ clause fields are evaluated based on other fields in the table.



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# File 'lib/trix51db.rb', line 280

def create_table( tablename, args, classname = 'Trix51::Tuple' )
  
  mref = @dbm[ Trix51::META_PREFIX+tablename.to_s ]
  
  if not mref.nil? then
    raise Trix51::TableExistsError, "Attempt to create a table that exists..."
  end
                      
  # create it
  @dbm[	Trix51::META_PREFIX+tablename.to_s ] = Marshal.dump(
    tablename: tablename,
    structure: args,
    classname: classname
  )
  @tables[tablename] = Trix51::Table.new( tablename, @dbm )
	
         Trix51.add_helper(  @tables[tablename].classname, self,  @tables[tablename] )	  
  
  return @tables[tablename]
  
end

#get_table(tablename) ⇒ Object

Example

animal = db.get_table( :animal )

Note: you can also use the alias db.animal to access it.



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# File 'lib/trix51db.rb', line 235

def get_table( tablename )
  
    # do we have a cached object?
    mref = @dbm[ Trix51::META_PREFIX+tablename.to_s ]
  
    if @tables[tablename].nil? then
      mref = @dbm[ Trix51::META_PREFIX+tablename.to_s ]
      raise Trix51::NotFoundError, "Table #{tablename.to_s} does not exist." if mref.nil?
      @tables[tablename] = Trix51::Table.new( tablename.to_s, @dbm )
      @tables[tablename].indices_load( @args[:path] )
    end
    
    return @tables[tablename]
    
end

#has_table?(table) ⇒ Boolean

Return true or false if a given table exists.

Returns:

  • (Boolean) 


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# File 'lib/trix51db.rb', line 321

def has_table?( table ) 
  return (self.tables.include?( table ))
end

#tables ⇒ Object

Provides a list of the tables in the database.



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# File 'lib/trix51db.rb', line 303

def tables
  list = []
  @dbm.each_key do |k|
    if k.match( Trix51::META_PREFIX )
      list.push( k.gsub( Trix51::META_PREFIX, '' ).to_sym )
    end
  end
  return list
end