Module: ActiveRecord::ModelSchema::ClassMethods

Defined in:
lib/active_record/model_schema.rb

Instance Method Summary collapse

Instance Method Details

#_default_attributes ⇒ Object

:nodoc:



383
384
385
 
# File 'lib/active_record/model_schema.rb', line 383

def _default_attributes # :nodoc:
  @default_attributes ||= AttributeSet.new({})
end

#attribute_types ⇒ Object

:nodoc:



352
353
354
355
 
# File 'lib/active_record/model_schema.rb', line 352

def attribute_types # :nodoc:
  load_schema
  @attribute_types ||= Hash.new(Type::Value.new)
end

#attributes_builder ⇒ Object

:nodoc:



334
335
336
337
338
339
340
 
# File 'lib/active_record/model_schema.rb', line 334

def attributes_builder # :nodoc:
  @attributes_builder ||= AttributeSet::Builder.new(attribute_types, primary_key) do |name|
    unless columns_hash.key?(name)
      _default_attributes[name].dup
    end
  end
end

#column_defaults ⇒ Object

Returns a hash where the keys are column names and the values are default values when instantiating the Active Record object for this table.



378
379
380
381
 
# File 'lib/active_record/model_schema.rb', line 378

def column_defaults
  load_schema
  _default_attributes.to_hash
end

#column_names ⇒ Object

Returns an array of column names as strings.



388
389
390
 
# File 'lib/active_record/model_schema.rb', line 388

def column_names
  @column_names ||= columns.map(&:name)
end

#columns ⇒ Object 



347
348
349
350
 
# File 'lib/active_record/model_schema.rb', line 347

def columns
  load_schema
  @columns ||= columns_hash.values
end

#columns_hash ⇒ Object

:nodoc:



342
343
344
345
 
# File 'lib/active_record/model_schema.rb', line 342

def columns_hash # :nodoc:
  load_schema
  @columns_hash
end

#content_columns ⇒ Object

Returns an array of column objects where the primary id, all columns ending in “_id” or “_count”, and columns used for single table inheritance have been removed.



394
395
396
 
# File 'lib/active_record/model_schema.rb', line 394

def content_columns
  @content_columns ||= columns.reject { |c| c.name == primary_key || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
end

#full_table_name_prefix ⇒ Object

:nodoc:



258
259
260
 
# File 'lib/active_record/model_schema.rb', line 258

def full_table_name_prefix #:nodoc:
  (parents.detect{ |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix
end

#full_table_name_suffix ⇒ Object

:nodoc:



262
263
264
 
# File 'lib/active_record/model_schema.rb', line 262

def full_table_name_suffix #:nodoc:
  (parents.detect {|p| p.respond_to?(:table_name_suffix) } || self).table_name_suffix
end

#inheritance_column ⇒ Object

Defines the name of the table column which will store the class name on single-table inheritance situations.

The default inheritance column name is type, which means it’s a reserved word inside Active Record. To be able to use single-table inheritance with another column name, or to use the column type in your own model for something else, you can set inheritance_column:

self.inheritance_column = 'zoink'



275
276
277
 
# File 'lib/active_record/model_schema.rb', line 275

def inheritance_column
  (@inheritance_column ||= nil) || superclass.inheritance_column
end

#inheritance_column=(value) ⇒ Object

Sets the value of inheritance_column



280
281
282
283
 
# File 'lib/active_record/model_schema.rb', line 280

def inheritance_column=(value)
  @inheritance_column = value.to_s
  @explicit_inheritance_column = true
end

#next_sequence_value ⇒ Object

Returns the next value that will be used as the primary key on an insert statement.



325
326
327
 
# File 'lib/active_record/model_schema.rb', line 325

def next_sequence_value
  connection.next_sequence_value(sequence_name)
end

#prefetch_primary_key? ⇒ Boolean

Determines if the primary key values should be selected from their corresponding sequence before the insert statement.

Returns:

  • (Boolean) 


319
320
321
 
# File 'lib/active_record/model_schema.rb', line 319

def prefetch_primary_key?
  connection.prefetch_primary_key?(table_name)
end

#quoted_table_name ⇒ Object

Returns a quoted version of the table name, used to construct SQL statements.



243
244
245
 
# File 'lib/active_record/model_schema.rb', line 243

def quoted_table_name
  @quoted_table_name ||= connection.quote_table_name(table_name)
end

#reset_column_information ⇒ Object

Resets all the cached information about columns, which will cause them to be reloaded on the next request.

The most common usage pattern for this method is probably in a migration, when just after creating a table you want to populate it with some default values, eg:

class CreateJobLevels < ActiveRecord::Migration[5.0]
  def up
    create_table :job_levels do |t|
      t.integer :id
      t.string :name

      t.timestamps
    end

    JobLevel.reset_column_information
    %w{assistant executive manager director}.each do |type|
      JobLevel.create(name: type)
    end
  end

  def down
    drop_table :job_levels
  end
end



424
425
426
427
428
429
430
431
 
# File 'lib/active_record/model_schema.rb', line 424

def reset_column_information
  connection.clear_cache!
  undefine_attribute_methods
  connection.schema_cache.clear_data_source_cache!(table_name)

  reload_schema_from_cache
  initialize_find_by_cache
end

#reset_sequence_name ⇒ Object

:nodoc:



293
294
295
296
 
# File 'lib/active_record/model_schema.rb', line 293

def reset_sequence_name #:nodoc:
  @explicit_sequence_name = false
  @sequence_name          = connection.default_sequence_name(table_name, primary_key)
end

#reset_table_name ⇒ Object

Computes the table name, (re)sets it internally, and returns it.



248
249
250
251
252
253
254
255
256
 
# File 'lib/active_record/model_schema.rb', line 248

def reset_table_name #:nodoc:
  self.table_name = if abstract_class?
    superclass == Base ? nil : superclass.table_name
  elsif superclass.abstract_class?
    superclass.table_name || compute_table_name
  else
    compute_table_name
  end
end

#sequence_name ⇒ Object 



285
286
287
288
289
290
291
 
# File 'lib/active_record/model_schema.rb', line 285

def sequence_name
  if base_class == self
    @sequence_name ||= reset_sequence_name
  else
    (@sequence_name ||= nil) || base_class.sequence_name
  end
end

#sequence_name=(value) ⇒ Object

Sets the name of the sequence to use when generating ids to the given value, or (if the value is nil or false) to the value returned by the given block. This is required for Oracle and is useful for any database which relies on sequences for primary key generation.

If a sequence name is not explicitly set when using Oracle, it will default to the commonly used pattern of: ##table_name_seq

If a sequence name is not explicitly set when using PostgreSQL, it will discover the sequence corresponding to your primary key for you.

class Project < ActiveRecord::Base
  self.sequence_name = "projectseq"   # default would have been "project_seq"
end



312
313
314
315
 
# File 'lib/active_record/model_schema.rb', line 312

def sequence_name=(value)
  @sequence_name          = value.to_s
  @explicit_sequence_name = true
end

#table_exists? ⇒ Boolean

Indicates whether the table associated with this class exists

Returns:

  • (Boolean) 


330
331
332
 
# File 'lib/active_record/model_schema.rb', line 330

def table_exists?
  connection.schema_cache.data_source_exists?(table_name)
end

#table_name ⇒ Object

Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.

Nested classes are given table names prefixed by the singular form of the parent’s table name. Enclosing modules are not considered.

Examples

class Invoice < ActiveRecord::Base
end

file                  class               table_name
invoice.rb            Invoice             invoices

class Invoice < ActiveRecord::Base
  class Lineitem < ActiveRecord::Base
  end
end

file                  class               table_name
invoice.rb            Invoice::Lineitem   invoice_lineitems

module Invoice
  class Lineitem < ActiveRecord::Base
  end
end

file                  class               table_name
invoice/lineitem.rb   Invoice::Lineitem   lineitems

Additionally, the class-level table_name_prefix is prepended and the table_name_suffix is appended. So if you have “myapp_” as a prefix, the table name guess for an Invoice class becomes “myapp_invoices”. Invoice::Lineitem becomes “myapp_invoice_lineitems”.

You can also set your own table name explicitly:

class Mouse < ActiveRecord::Base
  self.table_name = "mice"
end



217
218
219
220
 
# File 'lib/active_record/model_schema.rb', line 217

def table_name
  reset_table_name unless defined?(@table_name)
  @table_name
end

#table_name=(value) ⇒ Object

Sets the table name explicitly. Example:

class Project < ActiveRecord::Base
  self.table_name = "project"
end



227
228
229
230
231
232
233
234
235
236
237
238
239
240
 
# File 'lib/active_record/model_schema.rb', line 227

def table_name=(value)
  value = value && value.to_s

  if defined?(@table_name)
    return if value == @table_name
    reset_column_information if connected?
  end

  @table_name        = value
  @quoted_table_name = nil
  @arel_table        = nil
  @sequence_name     = nil unless defined?(@explicit_sequence_name) && @explicit_sequence_name
  @predicate_builder = nil
end

#type_for_attribute(attr_name, &block) ⇒ Object

Returns the type of the attribute with the given name, after applying all modifiers. This method is the only valid source of information for anything related to the types of a model’s attributes. This method will access the database and load the model’s schema if it is required.

The return value of this method will implement the interface described by ActiveModel::Type::Value (though the object itself may not subclass it).

attr_name The name of the attribute to retrieve the type for. Must be a string



368
369
370
371
372
373
374
 
# File 'lib/active_record/model_schema.rb', line 368

def type_for_attribute(attr_name, &block)
  if block
    attribute_types.fetch(attr_name, &block)
  else
    attribute_types[attr_name]
  end
end