module Sequel::Model::ClassMethods

Lets you create a Model subclass with its dataset already set. source should be an instance of one of the following classes:

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
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

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', ...}>

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.

Clear the setter_methods cache

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.

Artist.columns
# => [:id, :name]

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|
  a.name = 'Jim'
end # INSERT INTO artists (name) VALUES ('Jim')

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

Alias of set_dataset

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
  end
end
Album.dataset.foo
# => :bar
Album.foo
# => :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
end
Album.released.sql
# => "SELECT * FROM artists WHERE (release_date <= CURRENT_DATE)"
Album.by_release_date.sql
# => "SELECT * FROM artists ORDER BY release_date"
Album.for_select_options.sql
# => "SELECT id, name, release_date FROM artists"
Album.released.by_release_date.for_select_options.sql
# => "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.

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

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 = Class.new(Sequel::Model)
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.

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.

Artist.db_schema
# {:id=>{:type=>:integer, :primary_key=>true, ...},
#  :name=>{:type=>:string, :primary_key=>false, ...}}

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 = Class.new(Sequel::Model)
  Model.def_Model(self)
  DB = Model.db = Sequel.connect(ENV['FOO_DATABASE_URL'])
  Model.plugin :prepared_statements

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

  class Baz < Model(:my_baz)
    # Uses Foo::DB[:my_baz]
  end
end

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

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

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')

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

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.

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

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

Calls call with the values hash.

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.no_primary_key
Artist.primary_key # => nil

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.

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}

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.

Artist.where(Artist.qualified_primary_key_hash(1))
# SELECT * FROM artists WHERE (artists.id = 1)

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.

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

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)
end

# dataset
class Artist < Sequel::Model(DB[:tbl_artists])
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
end

class Tagging < Sequel::Model
  # composite key
  set_primary_key [:taggable_id, :tag_id]
end

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

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

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.unrestrict_primary_key
Artist.set(id: 1) # No Error

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

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