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# postgresql_adaptor.rb
# author: Luke Holden <lholden@cablelan.net>
# notes: Currently this adaptor does not pass the test_zero_date_fields
# and test_zero_datetime_fields unit tests in the BasicsTest test
# group.
#
# This is due to the fact that, in postgresql you can not have a
# totally zero timestamp. Instead null/nil should be used to
# represent no value.
#
require 'active_record/connection_adapters/abstract_adapter'
require 'parsedate'
module ActiveRecord
class Base
# Establishes a connection to the database that's used by all Active Record objects
def self.postgresql_connection(config) # :nodoc:
require_library_or_gem 'postgres' unless self.class.const_defined?(:PGconn)
symbolize_strings_in_hash(config)
host = config[:host]
port = config[:port] || 5432 unless host.nil?
username = config[:username].to_s
password = config[:password].to_s
encoding = config[:encoding]
min_messages = config[:min_messages]
if config.has_key?(:database)
database = config[:database]
else
raise ArgumentError, "No database specified. Missing argument: database."
end
pga = ConnectionAdapters::PostgreSQLAdapter.new(
PGconn.connect(host, port, "", "", database, username, password), logger
)
pga.schema_search_path = config[:schema_search_path] || config[:schema_order]
pga.execute("SET client_encoding TO '#{encoding}'") if encoding
pga.execute("SET client_min_messages TO '#{min_messages}'") if min_messages
pga
end
end
module ConnectionAdapters
# The PostgreSQL adapter works both with the C-based (http://www.postgresql.jp/interfaces/ruby/) and the Ruby-base
# (available both as gem and from http://rubyforge.org/frs/?group_id=234&release_id=1145) drivers.
#
# Options:
#
# * <tt>:host</tt> -- Defaults to localhost
# * <tt>:port</tt> -- Defaults to 5432
# * <tt>:username</tt> -- Defaults to nothing
# * <tt>:password</tt> -- Defaults to nothing
# * <tt>:database</tt> -- The name of the database. No default, must be provided.
# * <tt>:schema_search_path</tt> -- An optional schema search path for the connection given as a string of comma-separated schema names. This is backward-compatible with the :schema_order option.
# * <tt>:encoding</tt> -- An optional client encoding that is using in a SET client_encoding TO <encoding> call on connection.
# * <tt>:min_messages</tt> -- An optional client min messages that is using in a SET client_min_messages TO <min_messages> call on connection.
class PostgreSQLAdapter < AbstractAdapter
def native_database_types
{
:primary_key => "serial primary key",
:string => { :name => "character varying", :limit => 255 },
:text => { :name => "text" },
:integer => { :name => "integer" },
:float => { :name => "float" },
:datetime => { :name => "timestamp" },
:timestamp => { :name => "timestamp" },
:time => { :name => "timestamp" },
:date => { :name => "date" },
:binary => { :name => "bytea" },
:boolean => { :name => "boolean"}
}
end
def supports_migrations?
true
end
def select_all(sql, name = nil)
select(sql, name)
end
def select_one(sql, name = nil)
result = select(sql, name)
result.nil? ? nil : result.first
end
def columns(table_name, name = nil)
column_definitions(table_name).collect do |name, type, default|
Column.new(name, default_value(default), translate_field_type(type))
end
end
def insert(sql, name = nil, pk = nil, id_value = nil)
execute(sql, name)
table = sql.split(" ", 4)[2]
return id_value || last_insert_id(table, pk)
end
def query(sql, name = nil)
log(sql, name) { @connection.query(sql) }
end
def execute(sql, name = nil)
log(sql, name) { @connection.exec(sql) }
end
def update(sql, name = nil)
execute(sql, name).cmdtuples
end
alias_method :delete, :update
def begin_db_transaction() execute "BEGIN" end
def commit_db_transaction() execute "COMMIT" end
def rollback_db_transaction() execute "ROLLBACK" end
def quote(value, column = nil)
if value.class == String && column && column.type == :binary
quote_bytea(value)
else
super
end
end
def quote_column_name(name)
%("#{name}")
end
def adapter_name
'PostgreSQL'
end
# Set the schema search path to a string of comma-separated schema names.
# Names beginning with $ are quoted (e.g. $user => '$user')
# See http://www.postgresql.org/docs/8.0/interactive/ddl-schemas.html
def schema_search_path=(schema_csv)
if schema_csv
execute "SET search_path TO #{schema_csv}"
@schema_search_path = nil
end
end
def schema_search_path
@schema_search_path ||= query('SHOW search_path')[0][0]
end
def change_column(table_name, column_name, type, options = {})
execute = "ALTER TABLE #{table_name} ALTER #{column_name} TYPE #{type}"
change_column_default(table_name, column_name, options[:default]) unless options[:default].nil?
end
def change_column_default(table_name, column_name, default)
execute "ALTER TABLE #{table_name} ALTER COLUMN #{column_name} SET DEFAULT '#{default}'"
end
def rename_column(table_name, column_name, new_column_name)
execute "ALTER TABLE #{table_name} RENAME COLUMN #{column_name} TO #{new_column_name}"
end
def remove_index(table_name, column_name)
execute "DROP INDEX #{table_name}_#{column_name}_index"
end
private
BYTEA_COLUMN_TYPE_OID = 17
def last_insert_id(table, column = "id")
sequence_name = "#{table}_#{column || 'id'}_seq"
@connection.exec("SELECT currval('#{sequence_name}')")[0][0].to_i
end
def select(sql, name = nil)
res = execute(sql, name)
results = res.result
rows = []
if results.length > 0
fields = res.fields
results.each do |row|
hashed_row = {}
row.each_index do |cel_index|
column = row[cel_index]
if res.type(cel_index) == BYTEA_COLUMN_TYPE_OID
column = unescape_bytea(column)
end
hashed_row[fields[cel_index]] = column
end
rows << hashed_row
end
end
return rows
end
def quote_bytea(s)
"'#{escape_bytea(s)}'"
end
def escape_bytea(s)
s.gsub(/\\/) { '\\\\\\\\' }.gsub(/[^\\]/) { |c| sprintf('\\\\%03o', c[0].to_i) } unless s.nil?
end
def unescape_bytea(s)
s.gsub(/\\([0-9][0-9][0-9])/) { $1.oct.chr }.gsub(/\\\\/) { '\\' } unless s.nil?
end
# Query a table's column names, default values, and types.
#
# The underlying query is roughly:
# SELECT column.name, column.type, default.value
# FROM column LEFT JOIN default
# ON column.table_id = default.table_id
# AND column.num = default.column_num
# WHERE column.table_id = get_table_id('table_name')
# AND column.num > 0
# AND NOT column.is_dropped
# ORDER BY column.num
#
# If the table name is not prefixed with a schema, the database will
# take the first match from the schema search path.
#
# Query implementation notes:
# - format_type includes the column size constraint, e.g. varchar(50)
# - ::regclass is a function that gives the id for a table name
def column_definitions(table_name)
query <<-end_sql
SELECT a.attname, format_type(a.atttypid, a.atttypmod), d.adsrc
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '#{table_name}'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
end_sql
end
# Translate PostgreSQL-specific types into simplified SQL types.
# These are special cases; standard types are handled by
# ConnectionAdapters::Column#simplified_type.
def translate_field_type(field_type)
# Match the beginning of field_type since it may have a size constraint on the end.
case field_type
when /^timestamp/i then 'datetime'
when /^real|^money/i then 'float'
when /^interval/i then 'string'
when /^bytea/i then 'binary'
else field_type # Pass through standard types.
end
end
def default_value(value)
# Boolean types
return "t" if value =~ /true/i
return "f" if value =~ /false/i
# Char/String type values
return $1 if value =~ /^'(.*)'::(bpchar|text|character varying)$/
# Numeric values
return value if value =~ /^[0-9]+(\.[0-9]*)?/
# Date / Time magic values
return Time.now.to_s if value =~ /^\('now'::text\)::(date|timestamp)/
# Fixed dates / times
return $1 if value =~ /^'(.+)'::(date|timestamp)/
# Anything else is blank, some user type, or some function
# and we can't know the value of that, so return nil.
return nil
end
end
end
end
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