module Sequel
Top level module for Sequel
There are some module methods that are added via metaprogramming, one for each supported adapter. For example:
DB = Sequel.sqlite # Memory database DB = Sequel.sqlite('blog.db') DB = Sequel.postgres('database_name', user:'user', password: 'password', host: 'host' port: 5432, max_connections: 10)
If a block is given to these methods, it is passed the opened Database
object, which is closed (disconnected) when the block exits, just like a block passed to Sequel.connect
. For example:
Sequel.sqlite('blog.db'){|db| puts db[:users].count}
For a more expanded introduction, see the README. For a quicker introduction, see the cheat sheet.
The duplicate_columns_handler extension allows you to customize handling of duplicate column names in your queries on a per-database or per-dataset level.
For example, you may want to raise an exception if you join 2 tables together which contains a column that will override another columns.
To use the extension, you need to load the extension into the database:
DB.extension :duplicate_columns_handler
or into individual datasets:
ds = DB[:items].extension(:duplicate_columns_handler)
A database option is introduced: :on_duplicate_columns. It accepts a Symbol
or any object that responds to :call.
on_duplicate_columns: :raise on_duplicate_columns: :warn on_duplicate_columns: :ignore on_duplicate_columns: lambda{|columns| arbitrary_condition? ? :raise : :warn}
You may also configure duplicate columns handling for a specific dataset:
ds.on_duplicate_columns(:warn) ds.on_duplicate_columns(:raise) ds.on_duplicate_columns(:ignore) ds.on_duplicate_columns{|columns| arbitrary_condition? ? :raise : :warn} ds.on_duplicate_columns(lambda{|columns| arbitrary_condition? ? :raise : :warn})
If :raise is specified, a Sequel::DuplicateColumnError
is raised. If :warn is specified, you will receive a warning via warn
. If a callable is specified, it will be called. If no on_duplicate_columns is specified, the default is :warn.
Related module: Sequel::DuplicateColumnsHandler
The pg_range extension adds support for the PostgreSQL 9.2+ range types to Sequel
. PostgreSQL range types are similar to ruby's Range
class, representating an array of values. However, they are more flexible than ruby's ranges, allowing exclusive beginnings and endings (ruby's range only allows exclusive endings), and unbounded beginnings and endings (which ruby's range does not support).
This extension integrates with Sequel's native postgres and jdbc/postgresql adapters, so that when range type values are retrieved, they are parsed and returned as instances of Sequel::Postgres::PGRange
. PGRange mostly acts like a Range
, but it's not a Range
as not all PostgreSQL range type values would be valid ruby ranges. If the range type value you are using is a valid ruby range, you can call PGRange#to_range to get a Range
. However, if you call PGRange#to_range on a range type value uses features that ruby's Range
does not support, an exception will be raised.
In addition to the parser, this extension comes with literalizers for both PGRange and Range
that use the standard Sequel
literalization callbacks, so they work on all adapters.
To turn an existing Range
into a PGRange, use Sequel.pg_range:
Sequel.pg_range(range)
If you have loaded the core_extensions extension, or you have loaded the core_refinements extension and have activated refinements for the file, you can also use Range#pg_range
:
range.pg_range
You may want to specify a specific range type:
Sequel.pg_range(range, :daterange) range.pg_range(:daterange)
If you specify the range database type, Sequel
will automatically cast the value to that type when literalizing.
To use this extension, load it into the Database
instance:
DB.extension :pg_range
See the schema modification guide for details on using range type columns in CREATE/ALTER TABLE statements.
This extension makes it easy to add support for other range types. In general, you just need to make sure that the subtype is handled and has the appropriate converter installed. For user defined types, you can do this via:
DB.add_conversion_proc(subtype_oid){|string| }
Then you can call Sequel::Postgres::PGRange::DatabaseMethods#register_range_type
to automatically set up a handler for the range type. So if you want to support the timerange type (assuming the time type is already supported):
DB.register_range_type('timerange')
This extension integrates with the pg_array extension. If you plan to use arrays of range types, load the pg_array extension before the pg_range extension:
DB.extension :pg_array, :pg_range
Related module: Sequel::Postgres::PGRange
The round_timestamps extension will automatically round timestamp values to the database's supported level of precision before literalizing them.
For example, if the database supports millisecond precision, and you give it a Time value with microsecond precision, it will round it appropriately:
Time.at(1405341161.917999982833862) # default: 2014-07-14 14:32:41.917999 # with extension: 2014-07-14 14:32:41.918000
The round_timestamps extension correctly deals with databases that support millisecond or second precision. In addition to handling Time values, it also handles DateTime values and Sequel::SQLTime
values (for the TIME type).
To round timestamps for a single dataset:
ds = ds.extension(:round_timestamps)
To round timestamps for all datasets on a single database:
DB.extension(:round_timestamps)
Related module: Sequel::Dataset::RoundTimestamps
Constants
- ADAPTER_MAP
Hash
of adapters that have been used. The key is the adapter scheme symbol, and the value is theDatabase
subclass.- AdapterNotFound
Error
raised when the adapter requested doesn't exist or can't be loaded.- CheckConstraintViolation
Error
raised whenSequel
determines a database check constraint has been violated.- ConstraintViolation
Generic error raised when
Sequel
determines a database constraint has been violated.- DATABASES
Array
of all databases to whichSequel
has connected. If you are developing an application that can connect to an arbitrary number of databases, delete the database objects from this (or use the :keep_referenceDatabase
option or a block when connecting) or they will not get garbage collected.- DEFAULT_INFLECTIONS_PROC
Proc that is instance_execed to create the default inflections for both the model inflector and the inflector extension.
- DatabaseConnectionError
Error
raised when theSequel
is unable to connect to the database with the connection parameters it was given.- DatabaseDisconnectError
Error
raised by adapters when they determine that the connection to the database has been lost. Instructs the connection pool code to remove that connection from the pool so that other connections can be acquired automatically.- DatabaseError
Generic error raised by the database adapters, indicating a problem originating from the database server. Usually raised because incorrect
SQL
syntax is used.- DatabaseLockTimeout
Error
raised whenSequel
determines the database could not acquire a necessary lock before timing out. Use ofDataset#nowait
can often cause this exception when retrieving rows.- ForeignKeyConstraintViolation
Error
raised whenSequel
determines a database foreign key constraint has been violated.- InvalidOperation
Error
raised on an invalid operation, such as trying to update or delete a joined or grouped dataset when the database does not support that.- InvalidValue
Error
raised when attempting an invalid type conversion.- MAJOR
The major version of
Sequel
. Only bumped for major changes.- MINOR
The minor version of
Sequel
. Bumped for every non-patch level release, generally around once a month.- MassAssignmentRestriction
Raised when a mass assignment method is called in strict mode with either a restricted column or a column without a setter method.
- NoExistingObject
Exception class raised when
require_modification
is set and an UPDATE or DELETE statement to modify the dataset doesn't modify a single row.- NotNullConstraintViolation
Error
raised whenSequel
determines a database NOT NULL constraint has been violated.- OPTS
Frozen hash used as the default options hash for most options.
- PoolTimeout
Error
raised when the connection pool cannot acquire a database connection before the timeout.- Rollback
Error
that you should raise to signal a rollback of the current transaction. The transaction block will catch this exception, rollback the current transaction, and won't reraise it (unless a reraise is requested).- SHARED_ADAPTER_MAP
Hash
of shared adapters that have been registered. The key is the adapter scheme symbol, and the value is theSequel
module containing the shared adapter.- SPLIT_SYMBOL_CACHE
- SerializationFailure
Error
raised whenSequel
determines a serialization failure/deadlock in the database.- TINY
The tiny version of
Sequel
. Usually 0, only bumped for bugfix releases that fix regressions from previous versions.- UndefinedAssociation
Raised when an undefined association is used when eager loading.
- UniqueConstraintViolation
Error
raised whenSequel
determines a database unique constraint has been violated.- VERSION
The version of
Sequel
you are using, as a string (e.g. “2.11.0”)- VERSION_NUMBER
The version of
Sequel
you are using, as a number (2.11.0 -> 20110)- VIRTUAL_ROW
Attributes
Sequel
converts two digit years in Date
s and DateTime
s by default, so 01/02/03 is interpreted at January 2nd, 2003, and 12/13/99 is interpreted as December 13, 1999. You can override this to treat those dates as January 2nd, 0003 and December 13, 0099, respectively, by:
Sequel.convert_two_digit_years = false
Sequel
can use either Time
or DateTime
for times returned from the database. It defaults to Time
. To change it to DateTime
:
Sequel.datetime_class = DateTime
Note that Time
and DateTime
objects have a different API, and in cases where they implement the same methods, they often implement them differently (e.g. + using seconds on Time
and days on DateTime
).
Set whether Sequel
is being used in single threaded mode. by default, Sequel
uses a thread-safe connection pool, which isn't as fast as the single threaded connection pool, and also has some additional thread safety checks. If your program will only have one thread, and speed is a priority, you should set this to true:
Sequel.single_threaded = true
Public Class Methods
Returns true if the passed object could be a specifier of conditions, false otherwise. Currently, Sequel
considers hashes and arrays of two element arrays as condition specifiers.
Sequel.condition_specifier?({}) # => true Sequel.condition_specifier?([[1, 2]]) # => true Sequel.condition_specifier?([]) # => false Sequel.condition_specifier?([1]) # => false Sequel.condition_specifier?(1) # => false
# File lib/sequel/core.rb 72 def self.condition_specifier?(obj) 73 case obj 74 when Hash 75 true 76 when Array 77 !obj.empty? && !obj.is_a?(SQL::ValueList) && obj.all?{|i| i.is_a?(Array) && (i.length == 2)} 78 else 79 false 80 end 81 end
Creates a new database object based on the supplied connection string and optional arguments. The specified scheme determines the database class used, and the rest of the string specifies the connection options. For example:
DB = Sequel.connect('sqlite:/') # Memory database DB = Sequel.connect('sqlite://blog.db') # ./blog.db DB = Sequel.connect('sqlite:///blog.db') # /blog.db DB = Sequel.connect('postgres://user:password@host:port/database_name') DB = Sequel.connect('sqlite:///blog.db', max_connections: 10)
You can also pass a single options hash:
DB = Sequel.connect(adapter: 'sqlite', database: './blog.db')
If a block is given, it is passed the opened Database
object, which is closed when the block exits. For example:
Sequel.connect('sqlite://blog.db'){|db| puts db[:users].count}
If a block is not given, a reference to this database will be held in Sequel::DATABASES
until it is removed manually. This is by design, and used by Sequel::Model
to pick the default database. It is recommended to pass a block if you do not want the resulting Database
object to remain in memory until the process terminates, or use the keep_reference: false
Database
option.
For details, see the “Connecting to a Database” guide. To set up a master/slave or sharded database connection, see the “Master/Slave Databases and Sharding” guide.
# File lib/sequel/core.rb 115 def self.connect(*args, &block) 116 Database.connect(*args, &block) 117 end
Convert the exception
to the given class. The given class should be Sequel::Error
or a subclass. Returns an instance of klass
with the message and backtrace of exception
.
# File lib/sequel/core.rb 128 def self.convert_exception_class(exception, klass) 129 return exception if exception.is_a?(klass) 130 e = klass.new("#{exception.class}: #{exception.message}") 131 e.wrapped_exception = exception 132 e.set_backtrace(exception.backtrace) 133 e 134 end
Assume the core extensions are not loaded by default, if the core_extensions extension is loaded, this will be overridden.
# File lib/sequel/core.rb 121 def self.core_extensions? 122 false 123 end
The elapsed seconds since the given timer object was created. The timer object should have been created via Sequel.start_timer
.
# File lib/sequel/core.rb 322 def self.elapsed_seconds_since(timer) 323 start_timer - timer 324 end
Load all Sequel
extensions given. Extensions are just files that exist under sequel/extensions
in the load path, and are just required.
In some cases, requiring an extension modifies classes directly, and in others, it just loads a module that you can extend other classes with. Consult the documentation for each extension you plan on using for usage.
Sequel.extension(:blank) Sequel.extension(:core_extensions, :named_timezones)
# File lib/sequel/core.rb 144 def self.extension(*extensions) 145 extensions.each{|e| Kernel.require "sequel/extensions/#{e}"} 146 end
Yield the Inflections
module if a block is given, and return the Inflections
module.
# File lib/sequel/model/inflections.rb 6 def self.inflections 7 yield Inflections if block_given? 8 Inflections 9 end
The exception classed raised if there is an error parsing JSON. This can be overridden to use an alternative json implementation.
# File lib/sequel/core.rb 150 def self.json_parser_error_class 151 JSON::ParserError 152 end
The preferred method for writing Sequel
migrations, using a DSL:
Sequel.migration do up do create_table(:artists) do primary_key :id String :name end end down do drop_table(:artists) end end
Designed to be used with the Migrator
class, part of the migration
extension.
# File lib/sequel/extensions/migration.rb 288 def self.migration(&block) 289 MigrationDSL.create(&block) 290 end
Convert given object to json and return the result. This can be overridden to use an alternative json implementation.
# File lib/sequel/core.rb 156 def self.object_to_json(obj, *args, &block) 157 obj.to_json(*args, &block) 158 end
Parse the string as JSON and return the result. This can be overridden to use an alternative json implementation.
# File lib/sequel/core.rb 162 def self.parse_json(json) 163 JSON.parse(json, :create_additions=>false) 164 end
Convert each item in the array to the correct type, handling multi-dimensional arrays. For each element in the array or subarrays, call the converter, unless the value is nil.
# File lib/sequel/core.rb 169 def self.recursive_map(array, converter) 170 array.map do |i| 171 if i.is_a?(Array) 172 recursive_map(i, converter) 173 elsif !i.nil? 174 converter.call(i) 175 end 176 end 177 end
For backwards compatibility only. require_relative should be used instead.
# File lib/sequel/core.rb 180 def self.require(files, subdir=nil) 181 # Use Kernel.require_relative to work around JRuby 9.0 bug 182 Array(files).each{|f| Kernel.require_relative "#{"#{subdir}/" if subdir}#{f}"} 183 end
Splits the symbol into three parts, if symbol splitting is enabled (not the default). Each part will either be a string or nil. If symbol splitting is disabled, returns an array with the first and third parts being nil, and the second part beind a string version of the symbol.
For columns, these parts are the table, column, and alias. For tables, these parts are the schema, table, and alias.
# File lib/sequel/core.rb 194 def self.split_symbol(sym) 195 unless v = Sequel.synchronize{SPLIT_SYMBOL_CACHE[sym]} 196 if split_symbols? 197 v = case s = sym.to_s 198 when /\A((?:(?!__).)+)__((?:(?!___).)+)___(.+)\z/ 199 [$1.freeze, $2.freeze, $3.freeze].freeze 200 when /\A((?:(?!___).)+)___(.+)\z/ 201 [nil, $1.freeze, $2.freeze].freeze 202 when /\A((?:(?!__).)+)__(.+)\z/ 203 [$1.freeze, $2.freeze, nil].freeze 204 else 205 [nil, s.freeze, nil].freeze 206 end 207 else 208 v = [nil,sym.to_s.freeze,nil].freeze 209 end 210 Sequel.synchronize{SPLIT_SYMBOL_CACHE[sym] = v} 211 end 212 v 213 end
Setting this to true enables Sequel's historical behavior of splitting symbols on double or triple underscores:
:table__column # table.column :column___alias # column AS alias :table__column___alias # table.column AS alias
It is only recommended to turn this on for backwards compatibility until such symbols have been converted to use newer Sequel
APIs such as:
Sequel[:table][:column] # table.column Sequel[:column].as(:alias) # column AS alias Sequel[:table][:column].as(:alias) # table.column AS alias
Sequel::Database
instances do their own caching of literalized symbols, and changing this setting does not affect those caches. It is recommended that if you want to change this setting, you do so directly after requiring Sequel
, before creating any Sequel::Database
instances.
Disabling symbol splitting will also disable the handling of double underscores in virtual row methods, causing such methods to yield regular identifers instead of qualified identifiers:
# Sequel.split_symbols = true Sequel.expr{table__column} # table.column Sequel.expr{table[:column]} # table.column # Sequel.split_symbols = false Sequel.expr{table__column} # table__column Sequel.expr{table[:column]} # table.column
# File lib/sequel/core.rb 245 def self.split_symbols=(v) 246 Sequel.synchronize{SPLIT_SYMBOL_CACHE.clear} 247 @split_symbols = v 248 end
Whether Sequel
currently splits symbols into qualified/aliased identifiers.
# File lib/sequel/core.rb 251 def self.split_symbols? 252 @split_symbols 253 end
A timer object that can be passed to Sequel.elapsed_seconds_since
to return the number of seconds elapsed.
# File lib/sequel/core.rb 309 def self.start_timer 310 Process.clock_gettime(Process::CLOCK_MONOTONIC) 311 end
Converts the given string
into a Date
object.
Sequel.string_to_date('2010-09-10') # Date.civil(2010, 09, 10)
# File lib/sequel/core.rb 258 def self.string_to_date(string) 259 begin 260 Date.parse(string, Sequel.convert_two_digit_years) 261 rescue => e 262 raise convert_exception_class(e, InvalidValue) 263 end 264 end
Converts the given string
into a Time
or DateTime
object, depending on the value of Sequel.datetime_class
.
Sequel.string_to_datetime('2010-09-10 10:20:30') # Time.local(2010, 09, 10, 10, 20, 30)
# File lib/sequel/core.rb 270 def self.string_to_datetime(string) 271 begin 272 if datetime_class == DateTime 273 DateTime.parse(string, convert_two_digit_years) 274 else 275 datetime_class.parse(string) 276 end 277 rescue => e 278 raise convert_exception_class(e, InvalidValue) 279 end 280 end
Converts the given string
into a Sequel::SQLTime
object.
v = Sequel.string_to_time('10:20:30') # Sequel::SQLTime.parse('10:20:30') DB.literal(v) # => '10:20:30'
# File lib/sequel/core.rb 286 def self.string_to_time(string) 287 begin 288 SQLTime.parse(string) 289 rescue => e 290 raise convert_exception_class(e, InvalidValue) 291 end 292 end
Unless in single threaded mode, protects access to any mutable global data structure in Sequel
. Uses a non-reentrant mutex, so calling code should be careful. In general, this should only be used around the minimal possible code such as Hash#[], Hash#[]=, Hash#delete, Array#<<, and Array#delete.
# File lib/sequel/core.rb 302 def self.synchronize(&block) 303 @single_threaded ? yield : @data_mutex.synchronize(&block) 304 end
Uses a transaction on all given databases with the given options. This:
Sequel.transaction([DB1, DB2, DB3]){}
is equivalent to:
DB1.transaction do DB2.transaction do DB3.transaction do end end end
except that if Sequel::Rollback
is raised by the block, the transaction is rolled back on all databases instead of just the last one.
Note that this method cannot guarantee that all databases will commit or rollback. For example, if DB3 commits but attempting to commit on DB2
fails (maybe because foreign key checks are deferred), there is no way to uncommit the changes on DB3. For that kind of support, you need to have two-phase commit/prepared transactions (which Sequel
supports on some databases).
# File lib/sequel/core.rb 348 def self.transaction(dbs, opts=OPTS, &block) 349 unless opts[:rollback] 350 rescue_rollback = true 351 opts = Hash[opts].merge!(:rollback=>:reraise) 352 end 353 pr = dbs.reverse.inject(block){|bl, db| proc{db.transaction(opts, &bl)}} 354 if rescue_rollback 355 begin 356 pr.call 357 rescue Sequel::Rollback 358 nil 359 end 360 else 361 pr.call 362 end 363 end
The version of Sequel
you are using, as a string (e.g. “2.11.0”)
# File lib/sequel/version.rb 20 def self.version 21 VERSION 22 end
If the supplied block takes a single argument, yield an SQL::VirtualRow
instance to the block argument. Otherwise, evaluate the block in the context of a SQL::VirtualRow
instance.
Sequel.virtual_row{a} # Sequel::SQL::Identifier.new(:a) Sequel.virtual_row{|o| o.a} # Sequel::SQL::Function.new(:a)
# File lib/sequel/core.rb 372 def self.virtual_row(&block) 373 vr = VIRTUAL_ROW 374 case block.arity 375 when -1, 0 376 vr.instance_exec(&block) 377 else 378 block.call(vr) 379 end 380 end
Private Class Methods
Helper method that the database adapter class methods that are added to Sequel
via metaprogramming use to parse arguments.
# File lib/sequel/core.rb 386 def self.adapter_method(adapter, *args, &block) 387 options = args.last.is_a?(Hash) ? args.pop : OPTS 388 opts = {:adapter => adapter.to_sym} 389 opts[:database] = args.shift if args.first.is_a?(String) 390 if args.any? 391 raise ::Sequel::Error, "Wrong format of arguments, either use (), (String), (Hash), or (String, Hash)" 392 end 393 394 connect(opts.merge(options), &block) 395 end