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
MYSQL_TYPES | = | {} | Hash with integer keys and callable values for converting MySQL types. | |
PG_NAMED_TYPES | = | {} | Hash with type name symbols and callable values for converting PostgreSQL types. Non-builtin types that don‘t have fixed numbers should use this to register conversion procs. | |
PG_TYPES | = | {} | Hash with integer keys and callable values for converting PostgreSQL types. | |
SELECT_SERIAL_SEQUENCE | = | proc do |schema, table| <<-end_sql SELECT '"' || name.nspname || '".' || seq.relname || '' FROM pg_class seq, pg_attribute attr, pg_depend dep, pg_namespace name, pg_constraint cons WHERE seq.oid = dep.objid AND seq.relnamespace = name.oid AND seq.relkind = 'S' AND attr.attrelid = dep.refobjid AND attr.attnum = dep.refobjsubid AND attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1] AND cons.contype = 'p' #{"AND name.nspname = '#{schema}'" if schema} AND seq.relname = '#{table}' end_sql | ||
SQLITE_TYPES | = | {} | Hash with string keys and callable values for converting SQLite types. | |
ADAPTER_MAP | = | {} | Hash of adapters that have been used. The key is the adapter scheme symbol, and the value is the Database subclass. | |
DATABASES | = | [] | 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. | |
DEFAULT_INFLECTIONS_PROC | = | proc do plural(/$/, 's') | Proc that is instance evaled to create the default inflections for both the model inflector and the inflector extension. | |
BeforeHookFailed | = | HookFailed | Deprecated alias for HookFailed, kept for backwards compatibility | |
MAJOR | = | 3 | The major version of Sequel. Only bumped for major changes. | |
MINOR | = | 32 | The minor version of Sequel. Bumped for every non-patch level release, generally around once a month. | |
TINY | = | 0 | The tiny version of Sequel. Usually 0, only bumped for bugfix releases that fix regressions from previous versions. | |
VERSION | = | [MAJOR, MINOR, TINY].join('.') | The version of Sequel you are using, as a string (e.g. "2.11.0") |
convert_invalid_date_time | [RW] |
Whether to convert invalid date time values by default.
Only applies to Sequel::Database instances created after this has been set. |
convert_two_digit_years | [RW] |
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 |
datetime_class | [RW] |
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). |
empty_array_handle_nulls | [RW] |
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. |
use_iso_date_format | [R] | As an optimization, Sequel sets the date style to ISO, so that PostgreSQL provides the date in a known format that Sequel can parse faster. This can be turned off if you require a date style other than ISO. |
virtual_row_instance_eval | [RW] | For backwards compatibility, has no effect. |
Lets you create a Model subclass with its dataset already set. source should be an instance of one of the following classes:
Database : | 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) |
Dataset : | 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 37: def self.Model(source) 38: Model::ANONYMOUS_MODEL_CLASSES[source] ||= if source.is_a?(Database) 39: c = Class.new(Model) 40: c.db = source 41: c 42: else 43: Class.new(Model).set_dataset(source) 44: end 45: 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 111 111: def self.condition_specifier?(obj) 112: case obj 113: when Hash 114: true 115: when Array 116: !obj.empty? && !obj.is_a?(SQL::ValueList) && obj.all?{|i| (Array === i) && (i.length == 2)} 117: else 118: false 119: end 120: 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 140 140: def self.connect(*args, &block) 141: Database.connect(*args, &block) 142: 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 147 147: def self.convert_exception_class(exception, klass) 148: return exception if exception.is_a?(klass) 149: e = klass.new("#{exception.class}: #{exception.message}") 150: e.wrapped_exception = exception 151: e.set_backtrace(exception.backtrace) 152: e 153: 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 165 165: def self.extension(*extensions) 166: extensions.each{|e| tsk_require "sequel/extensions/#{e}"} 167: 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 180 180: def self.identifier_input_method=(value) 181: Database.identifier_input_method = value 182: 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 196 196: def self.identifier_output_method=(value) 197: Database.identifier_output_method = value 198: end
Yield the Inflections module if a block is given, and return the Inflections module.
# File lib/sequel/model/inflections.rb, line 4 4: def self.inflections 5: yield Inflections if block_given? 6: Inflections 7: end
Allowing loading the necessary JDBC support via a gem, which works for PostgreSQL, MySQL, and SQLite.
# File lib/sequel/adapters/jdbc.rb, line 123 123: def self.load_gem(name) 124: begin 125: Sequel.tsk_require "jdbc/#{name}" 126: rescue LoadError 127: # jdbc gem not used, hopefully the user has the .jar in their CLASSPATH 128: end 129: 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, line 241 241: def self.migration(&block) 242: MigrationDSL.create(&block) 243: 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 212 212: def self.require(files, subdir=nil) 213: Array(files).each{|f| super("#{File.dirname(__FILE__).untaint}/#{"#{subdir}/" if subdir}#{f}")} 214: 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 222 222: def self.single_threaded=(value) 223: Database.single_threaded = value 224: 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 229 229: def self.string_to_date(string) 230: begin 231: Date.parse(string, Sequel.convert_two_digit_years) 232: rescue => e 233: raise convert_exception_class(e, InvalidValue) 234: end 235: 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 241 241: def self.string_to_datetime(string) 242: begin 243: if datetime_class == DateTime 244: DateTime.parse(string, convert_two_digit_years) 245: else 246: datetime_class.parse(string) 247: end 248: rescue => e 249: raise convert_exception_class(e, InvalidValue) 250: end 251: 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 257 257: def self.string_to_time(string) 258: begin 259: SQLTime.parse(string) 260: rescue => e 261: raise convert_exception_class(e, InvalidValue) 262: end 263: 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 288 288: def self.transaction(dbs, opts={}, &block) 289: unless opts[:rollback] 290: rescue_rollback = true 291: opts = opts.merge(:rollback=>:reraise) 292: end 293: pr = dbs.reverse.inject(block){|bl, db| proc{db.transaction(opts, &bl)}} 294: if rescue_rollback 295: begin 296: pr.call 297: rescue Sequel::Rollback => e 298: nil 299: end 300: else 301: pr.call 302: end 303: end
Same as Sequel.require, but wrapped in a mutex in order to be thread safe.
# File lib/sequel/core.rb, line 306 306: def self.ts_require(*args) 307: check_requiring_thread{require(*args)} 308: end
Same as Kernel.require, but wrapped in a mutex in order to be thread safe.
# File lib/sequel/core.rb, line 311 311: def self.tsk_require(*args) 312: check_requiring_thread{k_require(*args)} 313: end
Modify the type translator for the date type depending on the value given.
# File lib/sequel/adapters/postgres.rb, line 125 125: def self.use_iso_date_format=(v) 126: PG_TYPES[1082] = v ? TYPE_TRANSLATOR.method(:date) : Sequel.method(:string_to_date) 127: @use_iso_date_format = v 128: 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 322 322: def self.virtual_row(&block) 323: vr = SQL::VirtualRow.new 324: case block.arity 325: when -1, 0 326: vr.instance_eval(&block) 327: else 328: block.call(vr) 329: end 330: end