module Sequel::Model::ClassMethods

  1. lib/sequel/model/base.rb

Class methods for Sequel::Model that implement basic model functionality.

  • All of the following methods have class methods created that send the method to the model’s dataset: all, as_hash, avg, count, cross_join, distinct, each, each_server, empty?, except, exclude, exclude_having, fetch_rows, filter, first, first!, for_update, from, from_self, full_join, full_outer_join, get, graph, grep, group, group_and_count, group_append, group_by, having, import, inner_join, insert, intersect, invert, join, join_table, last, left_join, left_outer_join, limit, lock_style, map, max, min, multi_insert, naked, natural_full_join, natural_join, natural_left_join, natural_right_join, offset, order, order_append, order_by, order_more, order_prepend, paged_each, qualify, reverse, reverse_order, right_join, right_outer_join, select, select_all, select_append, select_group, select_hash, select_hash_groups, select_map, select_more, select_order_map, select_prepend, server, single_record, single_record!, single_value, single_value!, sum, to_hash, to_hash_groups, truncate, unfiltered, ungraphed, ungrouped, union, unlimited, unordered, where, where_all, where_each, where_single_value, with, with_recursive, with_sql


cache_anonymous_models [RW]

Whether to cache the anonymous models created by Sequel::Model(), true by default. This is required for reloading them correctly (avoiding the superclass mismatch).

dataset_method_modules [R]

Array of modules that extend this model’s dataset. Stored so that if the model’s dataset is changed, it will be extended with all of these modules.

dataset_module_class [R]

The Module subclass to use for dataset_module blocks.

default_set_fields_options [RW]

The default options to use for Model#set_fields. These are merged with the options given to set_fields.

fast_instance_delete_sql [R]

SQL string fragment used for faster DELETE statement creation when deleting/destroying model instances, or nil if the optimization should not be used. For internal use only.

fast_pk_lookup_sql [R]

SQL string fragment used for faster lookups by primary key, or nil if the optimization should not be used. For internal use only.

instance_dataset [R]

The dataset that instance datasets (this) are based on. Generally a naked version of the model’s dataset limited to one row. For internal use only.

plugins [R]

Array of plugin modules loaded by this class

# => [Sequel::Model, Sequel::Model::Associations]
primary_key [R]

The primary key for the class. Sequel can determine this automatically for many databases, but not all, so you may need to set it manually. If not determined automatically, the default is :id.

raise_on_save_failure [RW]

Whether to raise an error instead of returning nil on a failure to save/create/save_changes/update/destroy due to a validation failure or a before_* hook returning false (default: true).

raise_on_typecast_failure [RW]

Whether to raise an error when unable to typecast data for a column (default: false). This should be set to true if you want to have model setter methods raise errors if the argument cannot be typecast properly.

require_modification [RW]

Whether to raise an error if an UPDATE or DELETE query related to a model instance does not modify exactly 1 row. If set to false, Sequel will not check the number of rows modified (default: true).

require_valid_table [RW]

If true (the default), requires that all models have valid tables, raising exceptions if creating a model without a valid table backing it. Setting this to false will allow the creation of model classes where the underlying table doesn’t exist.

simple_pk [R]

Should be the literal primary key column name if this Model’s table has a simple primary key, or nil if the model has a compound primary key or no primary key.

simple_table [R]

Should be the literal table name if this Model’s dataset is a simple table (no select, order, join, etc.), or nil otherwise. This and simple_pk are used for an optimization in Model.[].

strict_param_setting [RW]

Whether mass assigning via .create/.new/#set/#update should raise an error if an invalid key is used. A key is invalid if no setter method exists for that key or the access to the setter method is restricted (e.g. due to it being a primary key field). If set to false, silently skip any key where the setter method doesn’t exist or access to it is restricted.

typecast_empty_string_to_nil [RW]

Whether to typecast the empty string (”) to nil for columns that are not string or blob. In most cases the empty string would be the way to specify a NULL SQL value in string form (nil.to_s == ”), and an empty string would not usually be typecast correctly for other types, so the default is true.

typecast_on_assignment [RW]

Whether to typecast attribute values on assignment (default: true). If set to false, no typecasting is done, so it will be left up to the database to typecast the value correctly.

use_transactions [RW]

Whether to use a transaction by default when saving/deleting records (default: true). If you are sending database queries in before_* or after_* hooks, you shouldn’t change the default setting without a good reason.

Public Instance methods


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.


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 default table name that Sequel would use.

When creating subclasses of Sequel::Model itself, this method is usually called on Sequel itself, using Sequel::Model(:something).

# Using a symbol
class Comment < Sequel::Model(:something)
  table_name # => :something

# Using a dataset
class Comment < Sequel::Model(DB1[:something])
  dataset # => DB1[:something]

# Using a database
class Comment < Sequel::Model(DB1)
  dataset # => DB1[:comments]
[show source]
    # File lib/sequel/model/base.rb
179 def Model(source)
180   if cache_anonymous_models
181     cache = Sequel.synchronize{@Model_cache ||= {}}
182     if klass = Sequel.synchronize{cache[source]}
183       return klass
184     end
185   end
187   klass =
189   if source.is_a?(::Sequel::Database)
190     klass.db = source
191   else
192     klass.set_dataset(source)
193   end
195   if cache_anonymous_models
196     Sequel.synchronize{cache[source] = klass}
197   end
199   klass
200 end

Returns the first record from the database matching the conditions. If a hash is given, it is used as the conditions. If another object is given, it finds the first record whose primary key(s) match the given argument(s). If no object is returned by the dataset, returns nil.

Artist[1] # SELECT * FROM artists WHERE id = 1
# => #<Artist {:id=>1, ...}>

Artist[name: 'Bob'] # SELECT * FROM artists WHERE (name = 'Bob') LIMIT 1
# => #<Artist {:name=>'Bob', ...}>
[show source]
    # File lib/sequel/model/base.rb
212 def [](*args)
213   args = args.first if args.size <= 1
214   args.is_a?(Hash) ? first(args) : (primary_key_lookup(args) unless args.nil?)
215 end

Initializes a model instance as an existing record. This constructor is used by Sequel to initialize model instances when fetching records. Requires that values be a hash where all keys are symbols. It probably should not be used by external code.

[show source]
    # File lib/sequel/model/base.rb
221 def call(values)
222   o = allocate
223   o.instance_variable_set(:@values, values)
224   o
225 end

Clear the setter_methods cache

[show source]
    # File lib/sequel/model/base.rb
228 def clear_setter_methods_cache
229   @setter_methods = nil unless frozen?
230 end

Returns the columns in the result set in their original order. Generally, this will use the columns determined via the database schema, but in certain cases (e.g. models that are based on a joined dataset) it will use Dataset#columns to find the columns.

# => [:id, :name]
[show source]
    # File lib/sequel/model/base.rb
239 def columns
240   return @columns if @columns
241   return nil if frozen?
242   set_columns(dataset.naked.columns)
243 end
create(values = OPTS, &block)

Creates instance using new with the given values and block, and saves it.

Artist.create(name: 'Bob')
# INSERT INTO artists (name) VALUES ('Bob')

Artist.create do |a| = 'Jim'
end # INSERT INTO artists (name) VALUES ('Jim')
[show source]
    # File lib/sequel/model/base.rb
253 def create(values = OPTS, &block)
254   new(values, &block).save
255 end

Returns the dataset associated with the Model class. Raises an Error if there is no associated dataset for this class. In most cases, you don’t need to call this directly, as Model proxies many dataset methods to the underlying dataset.

Artist.dataset.all # SELECT * FROM artists
[show source]
    # File lib/sequel/model/base.rb
263 def dataset
264   @dataset || raise(Error, "No dataset associated with #{self}")
265 end

Alias of set_dataset

[show source]
    # File lib/sequel/model/base.rb
268 def dataset=(ds)
269   set_dataset(ds)
270 end
dataset_module(mod = nil, &block)

Extend the dataset with a module, similar to adding a plugin with the methods defined in DatasetMethods. This is the recommended way to add methods to model datasets.

If given an argument, it should be a module, and is used to extend the underlying dataset. Otherwise an anonymous module is created, and if a block is given, it is module_evaled, allowing you do define dataset methods directly using the standard ruby def syntax. Returns the module given or the anonymous module created.

# Usage with existing module
Album.dataset_module Sequel::ColumnsIntrospection

# Usage with anonymous module
Album.dataset_module do
  def foo
# => :bar
# => :bar

Any anonymous modules created are actually instances of Sequel::Model::DatasetModule (a Module subclass), which allows you to call the subset method on them, which defines a dataset method that adds a filter. There are also a number of other methods with the same names as the dataset methods, which can use to define named dataset methods:

Album.dataset_module do
  where(:released, Sequel[:release_date] <= Sequel::CURRENT_DATE)
  order :by_release_date, :release_date
  select :for_select_options, :id, :name, :release_date
# => "SELECT * FROM artists WHERE (release_date <= CURRENT_DATE)"
# => "SELECT * FROM artists ORDER BY release_date"
# => "SELECT id, name, release_date FROM artists"
# => "SELECT id, name, release_date FROM artists WHERE (release_date <= CURRENT_DATE) ORDER BY release_date"

The following methods are supported: distinct, eager, exclude, exclude_having, grep, group, group_and_count, group_append, having, limit, offset, order, order_append, order_prepend, select, select_all, select_append, select_group, where, and server.

The advantage of using these DatasetModule methods to define your dataset methods is that they can take advantage of dataset caching to improve performance.

Any public methods in the dataset module will have class methods created that call the method on the dataset, assuming that the class method is not already defined.

[show source]
    # File lib/sequel/model/base.rb
327 def dataset_module(mod = nil, &block)
328   if mod
329     raise Error, "can't provide both argument and block to Model.dataset_module" if block
330     dataset_extend(mod)
331     mod
332   else
333     @dataset_module ||=
334     @dataset_module.module_eval(&block) if block
335     dataset_extend(@dataset_module)
336     @dataset_module
337   end
338 end

Returns the database associated with the Model class. If this model doesn’t have a database associated with it, assumes the superclass’s database, or the first object in Sequel::DATABASES. If no Sequel::Database object has been created, raises an error.

Artist.db.transaction do # BEGIN
  Artist.create(name: 'Bob')
  # INSERT INTO artists (name) VALUES ('Bob')
end # COMMIT
[show source]
    # File lib/sequel/model/base.rb
350 def db
351   return @db if @db
352   @db = self == Model ? Sequel.synchronize{DATABASES.first} : superclass.db
353   raise(Error, "No database associated with #{self}: have you called Sequel.connect or #{self}.db= ?") unless @db
354   @db
355 end

Sets the database associated with the Model class. Should only be used if the Model class currently does not have a dataset defined.

This can be used directly on Sequel::Model to set the default database to be used by subclasses, or to override the database used for specific models:

Sequel::Model.db = DB1
Artist =
Artist.db = DB2

Note that you should not use this to change the model’s database at runtime. If you have that need, you should look into Sequel’s sharding support, or consider using separate model classes per Database.

[show source]
    # File lib/sequel/model/base.rb
371 def db=(db)
372   raise Error, "Cannot use Sequel::Model.db= on model with existing dataset.  Use Sequel::Model.dataset= instead." if @dataset
373   @db = db
374 end

Returns the cached schema information if available or gets it from the database. This is a hash where keys are column symbols and values are hashes of information related to the column. See Database#schema.

# {:id=>{:type=>:integer, :primary_key=>true, ...},
#  :name=>{:type=>:string, :primary_key=>false, ...}}
[show source]
    # File lib/sequel/model/base.rb
384 def db_schema
385   return @db_schema if @db_schema
386   return nil if frozen?
387   @db_schema = get_db_schema
388 end

Define a Model method on the given module that calls the Model method on the receiver. This is how the Sequel::Model() method is defined, and allows you to define Model() methods on other modules, making it easier to have custom model settings for all models under a namespace. Example:

module Foo
  Model =
  DB = Model.db = Sequel.connect(ENV['FOO_DATABASE_URL'])
  Model.plugin :prepared_statements

  class Bar < Model
    # Uses Foo::DB[:bars]

  class Baz < Model(:my_baz)
    # Uses Foo::DB[:my_baz]
[show source]
    # File lib/sequel/model/base.rb
137 def def_Model(mod)
138   model = self
139   mod.define_singleton_method(:Model) do |source|
140     model.Model(source)
141   end
142 end
def_column_alias(meth, column)

Create a column alias, where the column methods have one name, but the underlying storage uses a different name.

[show source]
    # File lib/sequel/model/base.rb
392 def def_column_alias(meth, column)
393   clear_setter_methods_cache
394   overridable_methods_module.module_eval do
395     define_method(meth){self[column]}
396     define_method("#{meth}="){|v| self[column] = v}
397   end
398 end
find(*args, &block)

Finds a single record according to the supplied filter. You are encouraged to use Model.[] or Model.first instead of this method.

Artist.find(name: 'Bob')
# SELECT * FROM artists WHERE (name = 'Bob') LIMIT 1

Artist.find{name > 'M'}
# SELECT * FROM artists WHERE (name > 'M') LIMIT 1
[show source]
    # File lib/sequel/model/base.rb
408 def find(*args, &block)
409   first(*args, &block)
410 end
find_or_create(cond, &block)

Like find but invokes create with given conditions when record does not exist. Unlike find in that the block used in this method is not passed to find, but instead is passed to create only if find does not return an object.

Artist.find_or_create(name: 'Bob')
# SELECT * FROM artists WHERE (name = 'Bob') LIMIT 1
# INSERT INTO artists (name) VALUES ('Bob')

Artist.find_or_create(name: 'Jim'){|a| a.hometown = 'Sactown'}
# SELECT * FROM artists WHERE (name = 'Jim') LIMIT 1
# INSERT INTO artists (name, hometown) VALUES ('Jim', 'Sactown')
[show source]
    # File lib/sequel/model/base.rb
424 def find_or_create(cond, &block)
425   find(cond) || create(cond, &block)
426 end

Freeze a model class, disallowing any further changes to it.

[show source]
    # File lib/sequel/model/base.rb
429 def freeze
430   return self if frozen?
431   dataset_module.freeze
432   overridable_methods_module.freeze
434   if @dataset
435     db_schema.freeze.each_value(&:freeze)
436     columns.freeze
437     setter_methods.freeze
438   else
439     @setter_methods = [].freeze
440   end
442   @dataset_method_modules.freeze
443   @default_set_fields_options.freeze
444   @plugins.freeze
446   super
447 end

Whether the model has a dataset. True for most model classes, but can be false if the model class is an abstract model class designed for subclassing, such as Sequel::Model itself.

[show source]
    # File lib/sequel/model/base.rb
452 def has_dataset?
453   !@dataset.nil?
454 end

Returns the implicit table name for the model class, which is the demodulized, underscored, pluralized name of the class.

Artist.implicit_table_name # => :artists
Foo::ArtistAlias.implicit_table_name # => :artist_aliases
[show source]
    # File lib/sequel/model/base.rb
468 def implicit_table_name
469   pluralize(underscore(demodulize(name))).to_sym
470 end

Clear the setter_methods cache when a module is included, as it may contain setter methods.

[show source]
    # File lib/sequel/model/base.rb
458 def include(*mods)
459   clear_setter_methods_cache
460   super
461 end

Calls call with the values hash.

[show source]
    # File lib/sequel/model/base.rb
473 def load(values)
474   call(values)
475 end

Mark the model as not having a primary key. Not having a primary key can cause issues, among which is that you won’t be able to update records.

Artist.primary_key # => :id
Artist.primary_key # => nil
[show source]
    # File lib/sequel/model/base.rb
483 def no_primary_key
484   clear_setter_methods_cache
485   self.simple_pk = @primary_key = nil
486 end
plugin(plugin, *args, &block)

Loads a plugin for use with the model class, passing optional arguments to the plugin. If the plugin is a module, load it directly. Otherwise, require the plugin from sequel/plugins/#{plugin} and then attempt to load the module using a the camelized plugin name under Sequel::Plugins.

[show source]
    # File lib/sequel/model/base.rb
492 def plugin(plugin, *args, &block)
493   m = plugin.is_a?(Module) ? plugin : plugin_module(plugin)
495   if !m.respond_to?(:apply) && !m.respond_to?(:configure) && (!args.empty? || block)
496     Deprecation.deprecate("Plugin #{plugin} accepts no arguments or block, and passing arguments/block to it", "Remove arguments and block when loading the plugin")
497   end
499   unless @plugins.include?(m)
500     @plugins << m
501     m.apply(self, *args, &block) if m.respond_to?(:apply)
502     extend(m::ClassMethods) if m.const_defined?(:ClassMethods, false)
503     include(m::InstanceMethods) if m.const_defined?(:InstanceMethods, false)
504     if m.const_defined?(:DatasetMethods, false)
505       dataset_extend(m::DatasetMethods, :create_class_methods=>false)
506     end
507   end
509   m.configure(self, *args, &block) if m.respond_to?(:configure)
510 end

Returns primary key attribute hash. If using a composite primary key value such be an array with values for each primary key in the correct order. For a standard primary key, value should be an object with a compatible type for the key. If the model does not have a primary key, raises an Error.

Artist.primary_key_hash(1) # => {:id=>1}
Artist.primary_key_hash([1, 2]) # => {:id1=>1, :id2=>2}
[show source]
    # File lib/sequel/model/base.rb
523 def primary_key_hash(value)
524   case key = @primary_key
525   when Symbol
526     {key => value}
527   when Array
528     hash = {}
529{|k,v| hash[k] = v}
530     hash
531   else
532     raise(Error, "#{self} does not have a primary key")
533   end
534 end
qualified_primary_key_hash(value, qualifier=table_name)

Return a hash where the keys are qualified column references. Uses the given qualifier if provided, or the table_name otherwise. This is useful if you plan to join other tables to this table and you want the column references to be qualified.

# SELECT * FROM artists WHERE ( = 1)
[show source]
    # File lib/sequel/model/base.rb
543 def qualified_primary_key_hash(value, qualifier=table_name)
544   case key = @primary_key
545   when Symbol
546     {, key) => value}
547   when Array
548     hash = {}
549{|k,v| hash[, k)] = v}
550     hash
551   else
552     raise(Error, "#{self} does not have a primary key")
553   end
554 end

Restrict the setting of the primary key(s) when using mass assignment (e.g. set). Because this is the default, this only make sense to use in a subclass where the parent class has used unrestrict_primary_key.

[show source]
    # File lib/sequel/model/base.rb
559 def restrict_primary_key
560   clear_setter_methods_cache
561   @restrict_primary_key = true
562 end

Whether or not setting the primary key(s) when using mass assignment (e.g. set) is restricted, true by default.

[show source]
    # File lib/sequel/model/base.rb
566 def restrict_primary_key?
567   @restrict_primary_key
568 end
set_dataset(ds, opts=OPTS)

Sets the dataset associated with the Model class. ds can be a Symbol, LiteralString, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression (all specifying a table name in the current database), or a Dataset. If a dataset is used, the model’s database is changed to the database of the given dataset. If a dataset is not used, a dataset is created from the current database with the table name given. Other arguments raise an Error. Returns self.

It also attempts to determine the database schema for the model, based on the given dataset.

Note that you should not use this to change the model’s dataset at runtime. If you have that need, you should look into Sequel’s sharding support, or creating a separate Model class per dataset

You should avoid calling this method directly if possible. Instead you should set the table name or dataset when creating the model class:

# table name
class Artist < Sequel::Model(:tbl_artists)

# dataset
class Artist < Sequel::Model(DB[:tbl_artists])
[show source]
    # File lib/sequel/model/base.rb
596 def set_dataset(ds, opts=OPTS)
597   inherited = opts[:inherited]
598   @dataset = convert_input_dataset(ds)
599   @require_modification = @dataset.provides_accurate_rows_matched? if require_modification.nil?
600   if inherited
601     self.simple_table = superclass.simple_table
602     @columns = superclass.instance_variable_get(:@columns)
603     @db_schema = superclass.instance_variable_get(:@db_schema)
604   else
605     @dataset = @dataset.with_extend(*@dataset_method_modules.reverse)
606     @db_schema = get_db_schema
607   end
609   @fast_pk_lookup_sql = @fast_instance_delete_sql = nil unless @dataset.supports_placeholder_literalizer?
610   reset_instance_dataset
611   self
612 end

Sets the primary key for this model. You can use either a regular or a composite primary key. To not use a primary key, set to nil or use no_primary_key. On most adapters, Sequel can automatically determine the primary key to use, so this method is not needed often.

class Person < Sequel::Model
  # regular key
  set_primary_key :person_id

class Tagging < Sequel::Model
  # composite key
  set_primary_key [:taggable_id, :tag_id]
[show source]
    # File lib/sequel/model/base.rb
628 def set_primary_key(key)
629   clear_setter_methods_cache
630   if key.is_a?(Array)
631     if key.length < 2
632       key = key.first
633     else
634       key = key.dup.freeze
635     end
636   end
637   self.simple_pk = if key && !key.is_a?(Array)
638     (@dataset || db).literal(key).freeze
639   end
640   @primary_key = key
641 end

Cache of setter methods to allow by default, in order to speed up mass assignment.

[show source]
    # File lib/sequel/model/base.rb
644 def setter_methods
645   @setter_methods || (@setter_methods = get_setter_methods)
646 end

Returns name of primary table for the dataset. If the table for the dataset is aliased, returns the aliased name.

Artist.table_name # => :artists
Sequel::Model(:foo).table_name # => :foo
Sequel::Model(Sequel[:foo].as(:bar)).table_name # => :bar
[show source]
    # File lib/sequel/model/base.rb
654 def table_name
655   dataset.first_source_alias
656 end

Allow the setting of the primary key(s) when using the mass assignment methods. Using this method can open up security issues, be very careful before using it.

Artist.set(id: 1) # Error
Artist.set(id: 1) # No Error
[show source]
    # File lib/sequel/model/base.rb
664 def unrestrict_primary_key
665   clear_setter_methods_cache
666   @restrict_primary_key = false
667 end

Return the model instance with the primary key, or nil if there is no matching record.

[show source]
    # File lib/sequel/model/base.rb
670 def with_pk(pk)
671   primary_key_lookup(pk)
672 end

Return the model instance with the primary key, or raise NoMatchingRow if there is no matching record.

[show source]
    # File lib/sequel/model/base.rb
675 def with_pk!(pk)
676   with_pk(pk) || raise(
677 end