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 connect. For example:
Sequel.sqlite('blog.db'){|db| puts db[:users].count}
You can set the SEQUEL_NO_CORE_EXTENSIONS constant or environment variable to have Sequel not extend the core classes.
For a more expanded introduction, see the README. For a quicker introduction, see the cheat sheet.
The sql_expr extension adds the sql_expr method to every object, which returns an object that works nicely with Sequel's DSL. This is best shown by example:
1.sql_expr < :a # 1 < a false.sql_expr & :a # FALSE AND a true.sql_expr | :a # TRUE OR a ~nil.sql_expr # NOT NULL "a".sql_expr + "b" # 'a' || 'b'
The query extension adds Sequel::Dataset#query which allows a different way to construct queries instead of the usual method chaining.
The pagination extension adds the Sequel::Dataset#paginate and each_page methods, which return paginated (limited and offset) datasets with some helpful methods that make creating a paginated display easier.
The columns_introspection extension attempts to introspect the selected columns for a dataset before issuing a query. If it thinks it can guess correctly at the columns the query will use, it will return the columns without issuing a database query. This method is not fool-proof, it's possible that some databases will use column names that Sequel does not expect.
To enable this for a single dataset, extend the dataset with Sequel::ColumnIntrospection. To enable this for all datasets, run:
Sequel::Dataset.introspect_all_columns
The thread_local_timezones extension allows you to set a per-thread timezone that will override the default global timezone while the thread is executing. The main use case is for web applications that execute each request in its own thread, and want to set the timezones based on the request. The most common example is having the database always store time in UTC, but have the application deal with the timezone of the current user. That can be done with:
Sequel.database_timezone = :utc # In each thread: Sequel.thread_application_timezone = current_user.timezone
This extension is designed to work with the named_timezones extension.
This extension adds the thread_application_timezone=, thread_database_timezone=, and thread_typecast_timezone= methods to the Sequel module. It overrides the application_timezone, database_timezone, and typecast_timezone methods to check the related thread local timezone first, and use it if present. If the related thread local timezone is not present, it falls back to the default global timezone.
There is one special case of note. If you have a default global timezone and you want to have a nil thread local timezone, you have to set the thread local value to :nil instead of nil:
Sequel.application_timezone = :utc Sequel.thread_application_timezone = nil Sequel.application_timezone # => :utc Sequel.thread_application_timezone = :nil Sequel.application_timezone # => nil
The pretty_table extension adds Sequel::Dataset#print and the Sequel::PrettyTable class for creating nice-looking plain-text tables.
The schema_dumper extension supports dumping tables and indexes in a Sequel::Migration format, so they can be restored on another database (which can be the same type or a different type than the current database). The main interface is through Sequel::Database#dump_schema_migration.
The LooserTypecasting extension changes the float and integer typecasting to use the looser .to_f and .to_i instead of the more strict Kernel.Float and Kernel.Integer. To use it, you should extend the database with the Sequel::LooserTypecasting module after loading the extension:
Sequel.extension :looser_typecasting DB.extend(Sequel::LooserTypecasting)
This adds a Sequel::Dataset#to_dot method. The to_dot method returns a string that can be processed by graphviz's dot program in order to get a visualization of the dataset. Basically, it shows a version of the dataset's abstract syntax tree.
Hash of adapters that have been used. The key is the adapter scheme symbol, and the value is the Database subclass.
Deprecated alias for HookFailed, kept for backwards compatibility
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.
Proc that is instance evaled to create the default inflections for both the model inflector and the inflector extension.
The major version of Sequel. Only bumped for major changes.
The minor version of Sequel. Bumped for every non-patch level release, generally around once a month.
The tiny version of Sequel. Usually 0, only bumped for bugfix releases that fix regressions from previous versions.
The version of Sequel you are using, as a string (e.g. "2.11.0")
Sequel converts two digit years in Dates and DateTimes 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
For ruby versions less than 1.9.2, Time has a limited range (1901 to 2038), so if you use datetimes out of that range, you need to switch to DateTime. Also, before 1.9.2, Time can only handle local and UTC times, not other timezones. 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).
Sets whether or not to attempt to handle NULL values correctly when given an empty array. By default:
DB[:a].filter(:b=>[]) # SELECT * FROM a WHERE (b != b) DB[:a].exclude(:b=>[]) # SELECT * FROM a WHERE (b = b)
However, some databases (e.g. MySQL) will perform very poorly with this type of query. You can set this to false to get the following behavior:
DB[:a].filter(:b=>[]) # SELECT * FROM a WHERE 1 = 0 DB[:a].exclude(:b=>[]) # SELECT * FROM a WHERE 1 = 1
This may not handle NULLs correctly, but can be much faster on some databases.
Lets you create a Model subclass with its dataset already set. source should be an instance of one of the following classes:
Sets the database for this model to source. Generally only useful when subclassing directly from the returned class, where the name of the subclass sets the table name (which is combined with the Database in source to create the dataset to use) | |
Sets the dataset for this model to source. | |
other |
Sets the table name for this model to source. The class will use the default database for model classes in order to create the dataset. |
The purpose of this method is to set the dataset/database automatically for a model class, if the table name doesn't match the implicit name. This is neater than using set_dataset inside the class, doesn't require a bogus query for the schema.
# Using a symbol class Comment < Sequel::Model(:something) table_name # => :something end # Using a dataset class Comment < Sequel::Model(DB1[:something]) dataset # => DB1[:something] end # Using a database class Comment < Sequel::Model(DB1) dataset # => DB1[:comments] end
# File lib/sequel/model.rb, line 37 def self.Model(source) Model::ANONYMOUS_MODEL_CLASSES[source] ||= if source.is_a?(Database) c = Class.new(Model) c.db = source c else Class.new(Model).set_dataset(source) end end
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, line 111 def self.condition_specifier?(obj) case obj when Hash true when Array !obj.empty? && !obj.is_a?(SQL::ValueList) && obj.all?{|i| (Array === i) && (i.length == 2)} else false end 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)
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}
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, line 140 def self.connect(*args, &block) Database.connect(*args, &block) 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, line 147 def self.convert_exception_class(exception, klass) return exception if exception.is_a?(klass) e = klass.new("#{exception.class}: #{exception.message}") e.wrapped_exception = exception e.set_backtrace(exception.backtrace) e end
Load all Sequel extensions given. Extensions are just files that exist under sequel/extensions in the load path, and are just required. Generally, extensions modify the behavior of Database and/or Dataset, but Sequel ships with some extensions that modify other classes that exist for backwards compatibility. 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(:schema_dumper) Sequel.extension(:pagination, :query)
# File lib/sequel/core.rb, line 165 def self.extension(*extensions) extensions.each{|e| tsk_require "sequel/extensions/#{e}"} end
Set the method to call on identifiers going into the database. This affects the literalization of identifiers by calling this method on them before they are input. Sequel upcases identifiers in all SQL strings for most databases, so to turn that off:
Sequel.identifier_input_method = nil
to downcase instead:
Sequel.identifier_input_method = :downcase
Other String instance methods work as well.
# File lib/sequel/core.rb, line 180 def self.identifier_input_method=(value) Database.identifier_input_method = value end
Set the method to call on identifiers coming out of the database. This affects the literalization of identifiers by calling this method on them when they are retrieved from the database. Sequel downcases identifiers retrieved for most databases, so to turn that off:
Sequel.identifier_output_method = nil
to upcase instead:
Sequel.identifier_output_method = :upcase
Other String instance methods work as well.
# File lib/sequel/core.rb, line 196 def self.identifier_output_method=(value) Database.identifier_output_method = value end
Yield the Inflections module if a block is given, and return the Inflections module.
# File lib/sequel/model/inflections.rb, line 4 def self.inflections yield Inflections if block_given? Inflections end
Alias to the standard version of require
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, line 241 def self.migration(&block) MigrationDSL.create(&block) end
Require all given files which should be in the same or a subdirectory of this file. If a subdir is given, assume all files are in that subdir. This is used to ensure that the files loaded are from the same version of Sequel as this file.
# File lib/sequel/core.rb, line 212 def self.require(files, subdir=nil) Array(files).each{|f| super("#{File.dirname(__FILE__).untaint}/#{"#{subdir}/" if subdir}#{f}")} end
Set whether to set the single threaded mode for all databases by default. By default, Sequel uses a thread-safe connection pool, which isn't as fast as the single threaded connection pool. If your program will only have one thread, and speed is a priority, you may want to set this to true:
Sequel.single_threaded = true
# File lib/sequel/core.rb, line 222 def self.single_threaded=(value) Database.single_threaded = value 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, line 229 def self.string_to_date(string) begin Date.parse(string, Sequel.convert_two_digit_years) rescue => e raise convert_exception_class(e, InvalidValue) end 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, line 241 def self.string_to_datetime(string) begin if datetime_class == DateTime DateTime.parse(string, convert_two_digit_years) else datetime_class.parse(string) end rescue => e raise convert_exception_class(e, InvalidValue) end 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, line 257 def self.string_to_time(string) begin SQLTime.parse(string) rescue => e raise convert_exception_class(e, InvalidValue) end 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, line 288 def self.transaction(dbs, opts={}, &block) unless opts[:rollback] rescue_rollback = true opts = opts.merge(:rollback=>:reraise) end pr = dbs.reverse.inject(block){|bl, db| proc{db.transaction(opts, &bl)}} if rescue_rollback begin pr.call rescue Sequel::Rollback => e nil end else pr.call end end
Same as Sequel.require, but wrapped in a mutex in order to be thread safe.
# File lib/sequel/core.rb, line 306 def self.ts_require(*args) check_requiring_thread{require(*args)} end
Same as Kernel.require, but wrapped in a mutex in order to be thread safe.
# File lib/sequel/core.rb, line 311 def self.tsk_require(*args) check_requiring_thread{k_require(*args)} end
The version of Sequel you are using, as a string (e.g. "2.11.0")
# File lib/sequel/version.rb, line 15 def self.version VERSION end
If the supplied block takes a single argument, yield a new SQL::VirtualRow instance to the block argument. Otherwise, evaluate the block in the context of a new 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, line 322 def self.virtual_row(&block) vr = SQL::VirtualRow.new case block.arity when -1, 0 vr.instance_eval(&block) else block.call(vr) end end
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