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.- Timezones
Backwards compatible alias
- 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
Public Class Methods
This extension loads the core extensions.
# File lib/sequel/extensions/core_extensions.rb 11 def Sequel.core_extensions? 12 true 13 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 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 289 def self.migration(&block) 290 MigrationDSL.create(&block) 291 end
The version of Sequel
you are using, as a string (e.g. “2.11.0”)
# File lib/sequel/version.rb 22 def self.version 23 VERSION 24 end