Module | Sequel::Model::ClassMethods
In: | lib/sequel/model/base.rb lib/sequel/model/plugins.rb

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

- All of the method names in Model::DATASET_METHODS have class methods created that call the Model‘s dataset with the method of the same name with the given arguments.

### Methods

[] clear_setter_methods_cache columns create dataset dataset= db db= db_schema def_dataset_method find find_or_create implicit_table_name inherited load method_added no_primary_key primary_key_hash qualified_primary_key_hash restrict_primary_key restrict_primary_key? set_allowed_columns set_dataset set_primary_key set_restricted_columns setter_methods subset table_name unrestrict_primary_key

### External Aliases

with_sql | -> | fetch
| Returns a copy of the model‘s dataset with custom SQL
      Artist.fetch("SELECT * FROM artists WHERE name LIKE 'A%'")
      Artist.fetch("SELECT * FROM artists WHERE id = ?", 1)

### Attributes

allowed_columns | [R] | Which columns should be the only columns allowed in a call to a mass assignment method (e.g. set) (default: not set, so all columns not otherwise restricted).
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_methods | [R] | Hash of dataset methods with method name keys and proc values that are stored so when the dataset changes, methods defined with def_dataset_method will be applied to the new dataset.
plugins | [R] | Array of plugin modules loaded by this class
      Sequel::Model.plugins
      # => [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/etc due to a validation failure or a before_* hook returning false.
raise_on_typecast_failure | [RW] | Whether to raise an error when unable to typecast data for a column (default: true). This should be set to false if you want to use validations to display nice error messages to the user (e.g. most web applications). You can use the validates_not_string validations (from either the validation_helpers or validation_class_methods standard plugins) in connection with option to check for typecast failures for columns that aren‘t blobs or strings.
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).
restricted_columns | [R] | Which columns are specifically restricted in a call to set/update/new/etc. (default: not set). Some columns are restricted regardless of this setting, such as the primary key column and columns in Model::RESTRICTED_SETTER_METHODS.
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 new/set/update and their variants 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

[](*args)

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', ...}>

[Source]

         # File lib/sequel/model/base.rb, line 98
     98:       def [](*args)
     99:         args = args.first if (args.size == 1)
    100:         args.is_a?(Hash) ? dataset[args] : primary_key_lookup(args)
    101:       end

clear_setter_methods_cache()

Clear the setter_methods cache

[Source]

         # File lib/sequel/model/base.rb, line 104
    104:       def clear_setter_methods_cache
    105:         @setter_methods = nil
    106:       end

columns()

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]

[Source]

         # File lib/sequel/model/base.rb, line 115
    115:       def columns
    116:         @columns || set_columns(dataset.naked.columns)
    117:       end

create(values = {}, &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|
        a.name = 'Jim'
      end # INSERT INTO artists (name) VALUES ('Jim')

[Source]

         # File lib/sequel/model/base.rb, line 127
    127:       def create(values = {}, &block)
    128:         new(values, &block).save
    129:       end

dataset()

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

[Source]

         # File lib/sequel/model/base.rb, line 137
    137:       def dataset
    138:         @dataset || raise(Error, "No dataset associated with #{self}")
    139:       end

dataset=(ds)

Alias of set_dataset

[Source]

         # File lib/sequel/model/base.rb, line 142
    142:       def dataset=(ds)
    143:         set_dataset(ds)
    144:       end

db()

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

[Source]

         # File lib/sequel/model/base.rb, line 156
    156:       def db
    157:         return @db if @db
    158:         @db = self == Model ? DATABASES.first : superclass.db
    159:         raise(Error, "No database associated with #{self}") unless @db
    160:         @db
    161:       end

db=(db)

Sets the database associated with the Model class. If the model has an associated dataset, sets the model‘s dataset to a dataset on the new database with the same options used by the current dataset. 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.db = DB2

[Source]

         # File lib/sequel/model/base.rb, line 173
    173:       def db=(db)
    174:         @db = db
    175:         set_dataset(db.dataset(@dataset.opts)) if @dataset
    176:       end

db_schema()

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, ...}}

[Source]

         # File lib/sequel/model/base.rb, line 186
    186:       def db_schema
    187:         @db_schema ||= get_db_schema
    188:       end

def_dataset_method(*args, &block)

If a block is given, define a method on the dataset (if the model currently has an dataset) with the given argument name using the given block. Also define a class method on the model that calls the dataset method. Stores the method name and block so that it can be reapplied if the model‘s dataset changes.

If a block is not given, just define a class method on the model for each argument that calls the dataset method of the same argument name.

      # Add new dataset method and class method that calls it
      Artist.def_dataset_method(:by_name){order(:name)}
      Artist.filter(:name.like('A%')).by_name
      Artist.by_name.filter(:name.like('A%'))

      # Just add a class method that calls an existing dataset method
      Artist.def_dataset_method(:server!)
      Artist.server!(:server1)

[Source]

         # File lib/sequel/model/base.rb, line 206
    206:       def def_dataset_method(*args, &block)
    207:         raise(Error, "No arguments given") if args.empty?
    208:         if block
    209:           raise(Error, "Defining a dataset method using a block requires only one argument") if args.length > 1
    210:           meth = args.first
    211:           @dataset_methods[meth] = block
    212:           dataset.meta_def(meth, &block) if @dataset
    213:         end
    214:         args.each{|arg| instance_eval("def #{arg}(*args, &block); dataset.#{arg}(*args, &block) end", __FILE__, __LINE__) unless respond_to?(arg)}
    215:       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

[Source]

         # File lib/sequel/model/base.rb, line 225
    225:       def find(*args, &block)
    226:         filter(*args, &block).first
    227:       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')

[Source]

         # File lib/sequel/model/base.rb, line 241
    241:       def find_or_create(cond, &block)
    242:         find(cond) || create(cond, &block)
    243:       end

implicit_table_name()

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

[Source]

         # File lib/sequel/model/base.rb, line 283
    283:       def implicit_table_name
    284:         pluralize(underscore(demodulize(name))).to_sym
    285:       end

inherited(subclass)

If possible, set the dataset for the model subclass as soon as it is created. Also, make sure the inherited class instance variables are copied into the subclass.

Sequel queries the database to get schema information as soon as a model class is created:

      class Artist < Sequel::Model # Causes schema query
      end

[Source]

         # File lib/sequel/model/base.rb, line 254
    254:       def inherited(subclass)
    255:         super
    256:         ivs = subclass.instance_variables.collect{|x| x.to_s}
    257:         EMPTY_INSTANCE_VARIABLES.each{|iv| subclass.instance_variable_set(iv, nil) unless ivs.include?(iv.to_s)}
    258:         INHERITED_INSTANCE_VARIABLES.each do |iv, dup|
    259:           next if ivs.include?(iv.to_s)
    260:           sup_class_value = instance_variable_get(iv)
    261:           sup_class_value = sup_class_value.dup if dup == :dup && sup_class_value
    262:           subclass.instance_variable_set(iv, sup_class_value)
    263:         end
    264:         unless ivs.include?("@dataset")
    265:           db
    266:           begin
    267:             if self == Model || !@dataset
    268:               subclass.set_dataset(subclass.implicit_table_name) unless subclass.name.empty?
    269:             elsif @dataset
    270:               subclass.set_dataset(@dataset.clone, :inherited=>true)
    271:             end
    272:           rescue
    273:             nil
    274:           end
    275:         end
    276:       end

load(values)

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

[Source]

         # File lib/sequel/model/base.rb, line 291
    291:       def load(values)
    292:         new(values, true)
    293:       end

method_added(meth)

Clear the setter_methods cache when a setter method is added

[Source]

         # File lib/sequel/model/base.rb, line 296
    296:       def method_added(meth)
    297:         clear_setter_methods_cache if meth.to_s =~ SETTER_METHOD_REGEXP
    298:         super
    299:       end

no_primary_key()

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

[Source]

         # File lib/sequel/model/base.rb, line 307
    307:       def no_primary_key
    308:         clear_setter_methods_cache
    309:         @simple_pk = @primary_key = nil
    310:       end

primary_key_hash(value)

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}

[Source]

         # File lib/sequel/model/base.rb, line 320
    320:       def primary_key_hash(value)
    321:         raise(Error, "#{self} does not have a primary key") unless key = @primary_key
    322:         case key
    323:         when Array
    324:           hash = {}
    325:           key.each_with_index{|k,i| hash[k] = value[i]}
    326:           hash
    327:         else
    328:           {key => value}
    329:         end
    330:       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.

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

[Source]

         # File lib/sequel/model/base.rb, line 339
    339:       def qualified_primary_key_hash(value, qualifier=table_name)
    340:         h = primary_key_hash(value)
    341:         h.to_a.each{|k,v| h[SQL::QualifiedIdentifier.new(qualifier, k)] = h.delete(k)}
    342:         h
    343:       end

restrict_primary_key()

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`.

[Source]

         # File lib/sequel/model/base.rb, line 348
    348:       def restrict_primary_key
    349:         clear_setter_methods_cache
    350:         @restrict_primary_key = true
    351:       end

restrict_primary_key?()

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

[Source]

         # File lib/sequel/model/base.rb, line 355
    355:       def restrict_primary_key?
    356:         @restrict_primary_key
    357:       end

set_allowed_columns(*cols)

Set the columns to allow when using mass assignment (e.g. `set`). Using this means that any columns not listed here will not be modified. If you have any virtual setter methods (methods that end in =) that you want to be used during mass assignment, they need to be listed here as well (without the =).

It may be better to use a method such as `set_only` instead of this in places where only certain columns may be allowed.

      Artist.set_allowed_columns(:name, :hometown)
      Artist.set(:name=>'Bob', :hometown=>'Sactown') # No Error
      Artist.set(:name=>'Bob', :records_sold=>30000) # Error

[Source]

         # File lib/sequel/model/base.rb, line 370
    370:       def set_allowed_columns(*cols)
    371:         clear_setter_methods_cache
    372:         @allowed_columns = cols
    373:       end

set_dataset(ds, opts={})

Sets the dataset associated with the Model class. `ds` can be a `Symbol` (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 symbol is used, a dataset is created from the current database with the table name given. Other arguments raise an `Error`. Returns self.

This changes the row_proc of the dataset to return model objects, extends the dataset with the dataset_method_modules, and defines methods on the dataset using the dataset_methods. It also attempts to determine the database schema for the model, based on the given dataset.

      Artist.set_dataset(:tbl_artists)
      Artist.set_dataset(DB[:artists])

[Source]

         # File lib/sequel/model/base.rb, line 390
    390:       def set_dataset(ds, opts={})
    391:         inherited = opts[:inherited]
    392:         @dataset = case ds
    393:         when Symbol
    394:           @simple_table = db.literal(ds)
    395:           db[ds]
    396:         when Dataset
    397:           @simple_table = nil
    398:           @db = ds.db
    399:           ds
    400:         else
    401:           raise(Error, "Model.set_dataset takes a Symbol or a Sequel::Dataset")
    402:         end
    403:         @dataset.row_proc = Proc.new{|r| load(r)}
    404:         @require_modification = Sequel::Model.require_modification.nil? ? @dataset.provides_accurate_rows_matched? : Sequel::Model.require_modification
    405:         if inherited
    406:           @simple_table = superclass.simple_table
    407:           @columns = @dataset.columns rescue nil
    408:         else
    409:           @dataset_method_modules.each{|m| @dataset.extend(m)} if @dataset_method_modules
    410:           @dataset_methods.each{|meth, block| @dataset.meta_def(meth, &block)} if @dataset_methods
    411:         end
    412:         @dataset.model = self if @dataset.respond_to?(:model=)
    413:         check_non_connection_error{@db_schema = (inherited ? superclass.db_schema : get_db_schema)}
    414:         self
    415:       end

set_primary_key(*key)

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`.

      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

[Source]

         # File lib/sequel/model/base.rb, line 430
    430:       def set_primary_key(*key)
    431:         clear_setter_methods_cache
    432:         key = key.flatten
    433:         @simple_pk = key.length == 1 ? db.literal(key.first) : nil
    434:         @primary_key = (key.length == 1) ? key[0] : key
    435:       end

set_restricted_columns(*cols)

Set the columns to restrict when using mass assignment (e.g. `set`). Using this means that attempts to call setter methods for the columns listed here will cause an exception or be silently skipped (based on the `strict_param_setting` setting. If you have any virtual setter methods (methods that end in =) that you want not to be used during mass assignment, they need to be listed here as well (without the =).

It may be better to use a method such as `set_except` instead of this in places where certain columns are restricted. In general, it‘s better to have a whitelist approach where you specify only what is allowed, as opposed to a blacklist approach that this method uses, where everything is allowed other than what you restrict.

      Artist.set_restricted_column(:records_sold)
      Artist.set(:name=>'Bob', :hometown=>'Sactown') # No Error
      Artist.set(:name=>'Bob', :records_sold=>30000) # Error

[Source]

         # File lib/sequel/model/base.rb, line 451
    451:       def set_restricted_columns(*cols)
    452:         clear_setter_methods_cache
    453:         @restricted_columns = cols
    454:       end

setter_methods()

Cache of setter methods to allow by default, in order to speed up new/set/update instance methods.

[Source]

         # File lib/sequel/model/base.rb, line 457
    457:       def setter_methods
    458:         @setter_methods ||= if allowed_columns
    459:           allowed_columns.map{|x| "#{x}="}
    460:         else
    461:           meths = instance_methods.collect{|x| x.to_s}.grep(SETTER_METHOD_REGEXP) - RESTRICTED_SETTER_METHODS
    462:           meths -= Array(primary_key).map{|x| "#{x}="} if primary_key && restrict_primary_key?
    463:           meths -= restricted_columns.map{|x| "#{x}="} if restricted_columns
    464:           meths
    465:         end
    466:       end

subset(name, *args, &block)

Shortcut for `def_dataset_method` that is restricted to modifying the dataset‘s filter. Sometimes thought of as a scope, and like most dataset methods, they can be chained. For example:

      Topic.subset(:joes, :username.like('%joe%'))
      Topic.subset(:popular){num_posts > 100}
      Topic.subset(:recent){created_on > Date.today - 7}

Allows you to do:

      Topic.joes.recent.popular

to get topics with a username that includes joe that have more than 100 posts and were created less than 7 days ago.

Both the args given and the block are passed to `Dataset#filter`.

[Source]

         # File lib/sequel/model/base.rb, line 486
    486:       def subset(name, *args, &block)
    487:         def_dataset_method(name){filter(*args, &block)}
    488:       end

table_name()

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(:foo___bar).table_name # => :bar

[Source]

         # File lib/sequel/model/base.rb, line 496
    496:       def table_name
    497:         dataset.first_source_alias
    498:       end

unrestrict_primary_key()

Allow the setting of the primary key(s) when using the mass assignment methods.

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

[Source]

         # File lib/sequel/model/base.rb, line 505
    505:       def unrestrict_primary_key
    506:         clear_setter_methods_cache
    507:         @restrict_primary_key = false
    508:       end

[Validate]