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database.rb
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database.rb
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require 'sequel_core/database/schema'
module Sequel
# Array of all databases to which Sequel has connected. If you are
# developing an application that can connect to an arbitrary number of
# databases, delete the database objects from this or they will not get
# garbage collected.
DATABASES = []
# A Database object represents a virtual connection to a database.
# The Database class is meant to be subclassed by database adapters in order
# to provide the functionality needed for executing queries.
class Database
include Schema::SQL
# Array of supported database adapters
ADAPTERS = %w'ado db2 dbi informix jdbc mysql odbc odbc_mssql openbase oracle postgres sqlite'.collect{|x| x.to_sym}
SQL_BEGIN = 'BEGIN'.freeze
SQL_COMMIT = 'COMMIT'.freeze
SQL_ROLLBACK = 'ROLLBACK'.freeze
# Hash of adapters that have been used
@@adapters = Hash.new
# Whether to use the single threaded connection pool by default
@@single_threaded = false
# Whether to quote identifiers (columns and tables) by default
@@quote_identifiers = true
# Array of SQL loggers to use for this database
attr_accessor :loggers
# The options for this database
attr_reader :opts
# The connection pool for this database
attr_reader :pool
# Whether to quote identifiers (columns and tables) for this database
attr_writer :quote_identifiers
# The prepared statement objects for this database, keyed by name
attr_reader :prepared_statements
# Constructs a new instance of a database connection with the specified
# options hash.
#
# Sequel::Database is an abstract class that is not useful by itself.
def initialize(opts = {}, &block)
@opts = opts
@quote_identifiers = opts.include?(:quote_identifiers) ? opts[:quote_identifiers] : @@quote_identifiers
@single_threaded = opts.include?(:single_threaded) ? opts[:single_threaded] : @@single_threaded
@schemas = nil
@prepared_statements = {}
@transactions = []
@pool = (@single_threaded ? SingleThreadedPool : ConnectionPool).new(connection_pool_default_options.merge(opts), &block)
@pool.connection_proc = proc{|server| connect(server)} unless block
@loggers = Array(opts[:logger]) + Array(opts[:loggers])
::Sequel::DATABASES.push(self)
end
### Class Methods ###
# The Database subclass for the given adapter scheme.
# Raises Sequel::Error::AdapterNotFound if the adapter
# could not be loaded.
def self.adapter_class(scheme)
scheme = scheme.to_s.gsub('-', '_').to_sym
if (klass = @@adapters[scheme]).nil?
# attempt to load the adapter file
begin
require "sequel_core/adapters/#{scheme}"
rescue LoadError => e
raise Error::AdapterNotFound, "Could not load #{scheme} adapter:\n #{e.message}"
end
# make sure we actually loaded the adapter
if (klass = @@adapters[scheme]).nil?
raise Error::AdapterNotFound, "Could not load #{scheme} adapter"
end
end
return klass
end
# Returns the scheme for the Database class.
def self.adapter_scheme
@scheme
end
# Connects to a database. See Sequel.connect.
def self.connect(conn_string, opts = {}, &block)
if conn_string.is_a?(String)
if conn_string =~ /\Ajdbc:/
c = adapter_class(:jdbc)
opts = {:uri=>conn_string}.merge(opts)
else
uri = URI.parse(conn_string)
scheme = uri.scheme
scheme = :dbi if scheme =~ /\Adbi-/
c = adapter_class(scheme)
uri_options = {}
uri.query.split('&').collect{|s| s.split('=')}.each{|k,v| uri_options[k.to_sym] = v} unless uri.query.blank?
opts = c.send(:uri_to_options, uri).merge(uri_options).merge(opts)
end
else
opts = conn_string.merge(opts)
c = adapter_class(opts[:adapter] || opts['adapter'])
end
# process opts a bit
opts = opts.inject({}) do |m, kv| k, v = *kv
k = :user if k.to_s == 'username'
m[k.to_sym] = v
m
end
if block
begin
yield(db = c.new(opts))
ensure
db.disconnect if db
::Sequel::DATABASES.delete(db)
end
nil
else
c.new(opts)
end
end
# Sets the default quote_identifiers mode for new databases.
# See Sequel.quote_identifiers=.
def self.quote_identifiers=(value)
@@quote_identifiers = value
end
# Sets the default single_threaded mode for new databases.
# See Sequel.single_threaded=.
def self.single_threaded=(value)
@@single_threaded = value
end
### Private Class Methods ###
# Sets the adapter scheme for the Database class. Call this method in
# descendnants of Database to allow connection using a URL. For example the
# following:
#
# class Sequel::MyDB::Database < Sequel::Database
# set_adapter_scheme :mydb
# ...
# end
#
# would allow connection using:
#
# Sequel.connect('mydb://user:password@dbserver/mydb')
def self.set_adapter_scheme(scheme) # :nodoc:
@scheme = scheme
@@adapters[scheme.to_sym] = self
end
# Converts a uri to an options hash. These options are then passed
# to a newly created database object.
def self.uri_to_options(uri) # :nodoc:
{ :user => uri.user,
:password => uri.password,
:host => uri.host,
:port => uri.port,
:database => (m = /\/(.*)/.match(uri.path)) && (m[1]) }
end
private_class_method :set_adapter_scheme, :uri_to_options
### Instance Methods ###
# Executes the supplied SQL statement. The SQL can be supplied as a string
# or as an array of strings. If an array is given, comments and excessive
# white space are removed. See also Array#to_sql.
def <<(sql)
execute_ddl((Array === sql) ? sql.to_sql : sql)
end
# Returns a dataset from the database. If the first argument is a string,
# the method acts as an alias for Database#fetch, returning a dataset for
# arbitrary SQL:
#
# DB['SELECT * FROM items WHERE name = ?', my_name].print
#
# Otherwise, acts as an alias for Database#from, setting the primary
# table for the dataset:
#
# DB[:items].sql #=> "SELECT * FROM items"
def [](*args, &block)
(String === args.first) ? fetch(*args, &block) : from(*args, &block)
end
# Call the prepared statement with the given name with the given hash
# of arguments.
def call(ps_name, hash={})
prepared_statements[ps_name].call(hash)
end
# Connects to the database. This method should be overridden by descendants.
def connect
raise NotImplementedError, "#connect should be overridden by adapters"
end
# Returns a blank dataset
def dataset
ds = Sequel::Dataset.new(self)
end
# Disconnects from the database. This method should be overridden by
# descendants.
def disconnect
raise NotImplementedError, "#disconnect should be overridden by adapters"
end
# Executes the given SQL. This method should be overridden in descendants.
def execute(sql, opts={})
raise NotImplementedError, "#execute should be overridden by adapters"
end
# Method that should be used when submitting any DDL (Data Definition
# Language) SQL. By default, calls execute_dui.
def execute_ddl(sql, opts={}, &block)
execute_dui(sql, opts, &block)
end
# Method that should be used when issuing a DELETE, UPDATE, or INSERT
# statement. By default, calls execute.
def execute_dui(sql, opts={}, &block)
execute(sql, opts, &block)
end
# Fetches records for an arbitrary SQL statement. If a block is given,
# it is used to iterate over the records:
#
# DB.fetch('SELECT * FROM items'){|r| p r}
#
# The method returns a dataset instance:
#
# DB.fetch('SELECT * FROM items').print
#
# Fetch can also perform parameterized queries for protection against SQL
# injection:
#
# DB.fetch('SELECT * FROM items WHERE name = ?', my_name).print
def fetch(sql, *args, &block)
ds = dataset
sql = sql.gsub('?') {|m| ds.literal(args.shift)}
ds.opts[:sql] = sql
ds.fetch_rows(sql, &block) if block
ds
end
alias_method :>>, :fetch
# Returns a new dataset with the from method invoked. If a block is given,
# it is used as a filter on the dataset.
def from(*args, &block)
ds = dataset.from(*args)
block ? ds.filter(&block) : ds
end
# Returns a single value from the database, e.g.:
#
# # SELECT 1
# DB.get(1) #=> 1
#
# # SELECT version()
# DB.get(:version[]) #=> ...
def get(expr)
dataset.get(expr)
end
# Returns a string representation of the database object including the
# class name and the connection URI (or the opts if the URI
# cannot be constructed).
def inspect
"#<#{self.class}: #{(uri rescue opts).inspect}>"
end
# Log a message at level info to all loggers. All SQL logging
# goes through this method.
def log_info(message, args=nil)
message = "#{message}; #{args.inspect}" if args
@loggers.each{|logger| logger.info(message)}
end
# Return the first logger or nil if no loggers are being used.
# Should only be used for backwards compatibility.
def logger
@loggers.first
end
# Replace the array of loggers with the given logger(s).
def logger=(logger)
@loggers = Array(logger)
end
# Returns true unless the database is using a single-threaded connection pool.
def multi_threaded?
!@single_threaded
end
# Returns a dataset modified by the given query block. See Dataset#query.
def query(&block)
dataset.query(&block)
end
# Returns true if the database quotes identifiers.
def quote_identifiers?
@quote_identifiers
end
# Returns a new dataset with the select method invoked.
def select(*args)
dataset.select(*args)
end
# Default serial primary key options.
def serial_primary_key_options
{:primary_key => true, :type => :integer, :auto_increment => true}
end
# Returns true if the database is using a single-threaded connection pool.
def single_threaded?
@single_threaded
end
# Acquires a database connection, yielding it to the passed block.
def synchronize(server=nil, &block)
@pool.hold(server || :default, &block)
end
# Returns true if a table with the given name exists.
def table_exists?(name)
begin
if respond_to?(:tables)
tables.include?(name.to_sym)
else
from(name).first
true
end
rescue
false
end
end
# Attempts to acquire a database connection. Returns true if successful.
# Will probably raise an error if unsuccessful.
def test_connection(server=nil)
synchronize(server){|conn|}
true
end
# A simple implementation of SQL transactions. Nested transactions are not
# supported - calling #transaction within a transaction will reuse the
# current transaction. Should be overridden for databases that support nested
# transactions.
def transaction(server=nil)
synchronize(server) do |conn|
return yield(conn) if @transactions.include?(Thread.current)
log_info(SQL_BEGIN)
conn.execute(SQL_BEGIN)
begin
@transactions << Thread.current
yield(conn)
rescue Exception => e
log_info(SQL_ROLLBACK)
conn.execute(SQL_ROLLBACK)
transaction_error(e)
ensure
unless e
log_info(SQL_COMMIT)
conn.execute(SQL_COMMIT)
end
@transactions.delete(Thread.current)
end
end
end
# Typecast the value to the given column_type. Can be overridden in
# adapters to support database specific column types.
def typecast_value(column_type, value)
return nil if value.nil?
case column_type
when :integer
Integer(value)
when :string
value.to_s
when :float
Float(value)
when :decimal
case value
when BigDecimal
value
when String, Float
value.to_d
when Integer
value.to_s.to_d
else
raise ArgumentError, "invalid value for BigDecimal: #{value.inspect}"
end
when :boolean
case value
when false, 0, "0", /\Af(alse)?\z/i
false
else
value.blank? ? nil : true
end
when :date
case value
when Date
value
when DateTime, Time
Date.new(value.year, value.month, value.day)
when String
value.to_date
else
raise ArgumentError, "invalid value for Date: #{value.inspect}"
end
when :time
case value
when Time
value
when String
value.to_time
else
raise ArgumentError, "invalid value for Time: #{value.inspect}"
end
when :datetime
raise(ArgumentError, "invalid value for #{tc}: #{value.inspect}") unless value.is_one_of?(DateTime, Date, Time, String)
if Sequel.datetime_class === value
# Already the correct class, no need to convert
value
else
# First convert it to standard ISO 8601 time, then
# parse that string using the time class.
(Time === value ? value.iso8601 : value.to_s).to_sequel_time
end
when :blob
value.to_blob
else
value
end
end
# Returns the URI identifying the database.
# This method can raise an error if the database used options
# instead of a connection string.
def uri
uri = URI::Generic.new(
self.class.adapter_scheme.to_s,
nil,
@opts[:host],
@opts[:port],
nil,
"/#{@opts[:database]}",
nil,
nil,
nil
)
uri.user = @opts[:user]
uri.password = @opts[:password] if uri.user
uri.to_s
end
alias_method :url, :uri
private
# Return the options for the given server by merging the generic
# options for all server with the specific options for the given
# server specified in the :servers option.
def server_opts(server)
opts = if @opts[:servers] && server_options = @opts[:servers][server]
case server_options
when Hash
@opts.merge(server_options)
when Proc
@opts.merge(server_options.call(self))
else
raise Error, 'Server opts should be a hash or proc'
end
else
@opts.dup
end
opts.delete(:servers)
opts
end
# The default options for the connection pool.
def connection_pool_default_options
{}
end
# Convert the given exception to a DatabaseError, keeping message
# and traceback.
def raise_error(exception, opts={})
if !opts[:classes] || exception.is_one_of?(*opts[:classes])
e = DatabaseError.new("#{exception.class} #{exception.message}")
e.set_backtrace(exception.backtrace)
raise e
else
raise
end
end
# Raise a database error unless the exception is an Error::Rollback.
def transaction_error(e, *classes)
raise_error(e, :classes=>classes) unless Error::Rollback === e
end
end
end