Module: Sequel::Model::ClassMethods

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

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

### External Aliases

with_sql | -> | fetch
| Returns a copy of the model‘s dataset with custom SQL

### Attributes

allowed_columns | [R] | Which columns should be the only columns allowed in a call to 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 plugins loaded by this class
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.
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).

[Source]

        # File lib/sequel/model/base.rb, line 87
    87:       def [](*args)
    88:         args = args.first if (args.size == 1)
    89:         args.is_a?(Hash) ? dataset[args] : primary_key_lookup(args)
    90:       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, which may be empty if the Dataset has no records.

[Source]

        # File lib/sequel/model/base.rb, line 97
    97:       def columns
    98:         @columns || set_columns(dataset.naked.columns)
    99:       end

create(values = {}, &block)

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

[Source]

         # File lib/sequel/model/base.rb, line 102
    102:       def create(values = {}, &block)
    103:         new(values, &block).save
    104:       end

dataset()

Returns the dataset associated with the Model class. Raises an error if there is no associated dataset for this class.

[Source]

         # File lib/sequel/model/base.rb, line 108
    108:       def dataset
    109:         @dataset || raise(Error, "No dataset associated with #{self}")
    110:       end

dataset=(ds, opts={})

Alias for set_dataset

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.

[Source]

         # File lib/sequel/model/base.rb, line 117
    117:       def db
    118:         return @db if @db
    119:         @db = self == Model ? DATABASES.first : superclass.db
    120:         raise(Error, "No database associated with #{self}") unless @db
    121:         @db
    122:       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.

[Source]

         # File lib/sequel/model/base.rb, line 128
    128:       def db=(db)
    129:         @db = db
    130:         set_dataset(db.dataset(@dataset.opts)) if @dataset
    131:       end

db_schema()

Returns the cached schema information if available or gets it from the database.

[Source]

         # File lib/sequel/model/base.rb, line 135
    135:       def db_schema
    136:         @db_schema ||= get_db_schema
    137:       end

def_dataset_method(*args, &block)

If a block is given, define a method on the dataset (if the model has an associated dataset) with the given argument name using the given block as well as a 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, define a method on the model for each argument that calls the dataset method of the same argument name.

[Source]

         # File lib/sequel/model/base.rb, line 146
    146:       def def_dataset_method(*args, &block)
    147:         raise(Error, "No arguments given") if args.empty?
    148:         if block_given?
    149:           raise(Error, "Defining a dataset method using a block requires only one argument") if args.length > 1
    150:           meth = args.first
    151:           @dataset_methods[meth] = block
    152:           dataset.meta_def(meth, &block) if @dataset
    153:         end
    154:         args.each{|arg| instance_eval("def #{arg}(*args, &block); dataset.#{arg}(*args, &block) end", __FILE__, __LINE__) unless respond_to?(arg)}
    155:       end

find(*args, &block)

Finds a single record according to the supplied filter, e.g.:

      Ticket.find :author => 'Sharon' # => record

You are encouraged to use Model.[] or Model.first instead of this method.

[Source]

         # File lib/sequel/model/base.rb, line 162
    162:       def find(*args, &block)
    163:         filter(*args, &block).first
    164:       end

find_or_create(cond)

Like find but invokes create with given conditions when record does not exist.

[Source]

         # File lib/sequel/model/base.rb, line 168
    168:       def find_or_create(cond)
    169:         find(cond) || create(cond)
    170:       end

implicit_table_name()

Returns the implicit table name for the model class.

[Source]

         # File lib/sequel/model/base.rb, line 200
    200:       def implicit_table_name
    201:         pluralize(underscore(demodulize(name))).to_sym
    202:       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.

[Source]

         # File lib/sequel/model/base.rb, line 175
    175:       def inherited(subclass)
    176:         super
    177:         ivs = subclass.instance_variables.collect{|x| x.to_s}
    178:         EMPTY_INSTANCE_VARIABLES.each{|iv| subclass.instance_variable_set(iv, nil) unless ivs.include?(iv.to_s)}
    179:         INHERITED_INSTANCE_VARIABLES.each do |iv, dup|
    180:           next if ivs.include?(iv.to_s)
    181:           sup_class_value = instance_variable_get(iv)
    182:           sup_class_value = sup_class_value.dup if dup == :dup && sup_class_value
    183:           subclass.instance_variable_set(iv, sup_class_value)
    184:         end
    185:         unless ivs.include?("@dataset")
    186:           db
    187:           begin
    188:             if self == Model || !@dataset
    189:               subclass.set_dataset(subclass.implicit_table_name) unless subclass.name.empty?
    190:             elsif @dataset
    191:               subclass.set_dataset(@dataset.clone, :inherited=>true)
    192:             end
    193:           rescue
    194:             nil
    195:           end
    196:         end
    197:       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 208
    208:       def load(values)
    209:         new(values, true)
    210:       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.

[Source]

         # File lib/sequel/model/base.rb, line 214
    214:       def no_primary_key
    215:         @simple_pk = @primary_key = nil
    216:       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.

[Source]

         # File lib/sequel/model/base.rb, line 223
    223:       def primary_key_hash(value)
    224:         raise(Error, "#{self} does not have a primary key") unless key = @primary_key
    225:         case key
    226:         when Array
    227:           hash = {}
    228:           key.each_with_index{|k,i| hash[k] = value[i]}
    229:           hash
    230:         else
    231:           {key => value}
    232:         end
    233:       end

restrict_primary_key()

Restrict the setting of the primary key(s) inside new/set/update. 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 238
    238:       def restrict_primary_key
    239:         @restrict_primary_key = true
    240:       end

restrict_primary_key?()

Whether or not setting the primary key inside new/set/update is restricted, true by default.

[Source]

         # File lib/sequel/model/base.rb, line 244
    244:       def restrict_primary_key?
    245:         @restrict_primary_key
    246:       end

set_allowed_columns(*cols)

Set the columns to allow in new/set/update. 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 in new/set/update, they need to be listed here as well (without the =).

It may be better to use (set|update)_only instead of this in places where only certain columns may be allowed.

[Source]

         # File lib/sequel/model/base.rb, line 255
    255:       def set_allowed_columns(*cols)
    256:         @allowed_columns = cols
    257:       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 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 given 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.

[Source]

         # File lib/sequel/model/base.rb, line 271
    271:       def set_dataset(ds, opts={})
    272:         inherited = opts[:inherited]
    273:         @dataset = case ds
    274:         when Symbol
    275:           @simple_table = db.literal(ds)
    276:           db[ds]
    277:         when Dataset
    278:           @simple_table = nil
    279:           @db = ds.db
    280:           ds
    281:         else
    282:           raise(Error, "Model.set_dataset takes a Symbol or a Sequel::Dataset")
    283:         end
    284:         @dataset.row_proc = Proc.new{|r| load(r)}
    285:         if inherited
    286:           @simple_table = superclass.simple_table
    287:           @columns = @dataset.columns rescue nil
    288:         else
    289:           @dataset_method_modules.each{|m| @dataset.extend(m)} if @dataset_method_modules
    290:           @dataset_methods.each{|meth, block| @dataset.meta_def(meth, &block)} if @dataset_methods
    291:         end
    292:         @dataset.model = self if @dataset.respond_to?(:model=)
    293:         begin
    294:           @db_schema = (inherited ? superclass.db_schema : get_db_schema)
    295:         rescue Sequel::DatabaseConnectionError
    296:           raise
    297:         rescue
    298:           nil
    299:         end
    300:         self
    301:       end

set_primary_key(*key)

Sets the primary key for this model. You can use either a regular or a composite primary key.

Example:

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

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

You can set it to nil to not have a primary key, but that cause certain things not to work, see no_primary_key.

[Source]

         # File lib/sequel/model/base.rb, line 320
    320:       def set_primary_key(*key)
    321:         key = key.flatten
    322:         @simple_pk = key.length == 1 ? db.literal(key.first) : nil
    323:         @primary_key = (key.length == 1) ? key[0] : key
    324:       end

set_restricted_columns(*cols)

Set the columns to restrict in new/set/update. 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 in new/set/update, they need to be listed here as well (without the =).

It may be better to use (set|update)_except instead of this in places where only certain columns may be allowed.

[Source]

         # File lib/sequel/model/base.rb, line 334
    334:       def set_restricted_columns(*cols)
    335:         @restricted_columns = cols
    336:       end

subset(name, *args, &block)

Defines a method that returns a filtered dataset. Subsets create dataset methods, so they can be chained for scoping. For example:

      Topic.subset(:joes, :username.like('%joe%'))
      Topic.subset(:popular){|o| o.num_posts > 100}
      Topic.subset(:recent){|o| o.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 355
    355:       def subset(name, *args, &block)
    356:         def_dataset_method(name){filter(*args, &block)}
    357:       end

table_name()

Returns name of primary table for the dataset.

[Source]

         # File lib/sequel/model/base.rb, line 360
    360:       def table_name
    361:         dataset.first_source_alias
    362:       end

unrestrict_primary_key()

Allow the setting of the primary key(s) inside new/set/update.

[Source]

         # File lib/sequel/model/base.rb, line 365
    365:       def unrestrict_primary_key
    366:         @restrict_primary_key = false
    367:       end

[Validate]