require 'yaml' require 'set' require 'active_support/benchmarkable' require 'active_support/dependencies' require 'active_support/descendants_tracker' require 'active_support/time' require 'active_support/core_ext/class/attribute_accessors' require 'active_support/core_ext/class/delegating_attributes' require 'active_support/core_ext/array/extract_options' require 'active_support/core_ext/hash/deep_merge' require 'active_support/core_ext/hash/slice' require 'active_support/core_ext/string/behavior' require 'active_support/core_ext/kernel/singleton_class' require 'active_support/core_ext/module/introspection' require 'active_support/core_ext/object/duplicable' require 'active_support/core_ext/class/subclasses' require 'arel' require 'active_record/errors' require 'active_record/log_subscriber' require 'active_record/explain_subscriber' module ActiveRecord #:nodoc: # = Active Record # # Active Record objects don't specify their attributes directly, but rather infer them from # the table definition with which they're linked. Adding, removing, and changing attributes # and their type is done directly in the database. Any change is instantly reflected in the # Active Record objects. The mapping that binds a given Active Record class to a certain # database table will happen automatically in most common cases, but can be overwritten for the uncommon ones. # # See the mapping rules in table_name and the full example in link:files/activerecord/README_rdoc.html for more insight. # # == Creation # # Active Records accept constructor parameters either in a hash or as a block. The hash # method is especially useful when you're receiving the data from somewhere else, like an # HTTP request. It works like this: # # user = User.new(name: "David", occupation: "Code Artist") # user.name # => "David" # # You can also use block initialization: # # user = User.new do |u| # u.name = "David" # u.occupation = "Code Artist" # end # # And of course you can just create a bare object and specify the attributes after the fact: # # user = User.new # user.name = "David" # user.occupation = "Code Artist" # # == Conditions # # Conditions can either be specified as a string, array, or hash representing the WHERE-part of an SQL statement. # The array form is to be used when the condition input is tainted and requires sanitization. The string form can # be used for statements that don't involve tainted data. The hash form works much like the array form, except # only equality and range is possible. Examples: # # class User < ActiveRecord::Base # def self.authenticate_unsafely(user_name, password) # where("user_name = '#{user_name}' AND password = '#{password}'").first # end # # def self.authenticate_safely(user_name, password) # where("user_name = ? AND password = ?", user_name, password).first # end # # def self.authenticate_safely_simply(user_name, password) # where(user_name: user_name, password: password).first # end # end # # The authenticate_unsafely method inserts the parameters directly into the query # and is thus susceptible to SQL-injection attacks if the user_name and +password+ # parameters come directly from an HTTP request. The authenticate_safely and # authenticate_safely_simply both will sanitize the user_name and +password+ # before inserting them in the query, which will ensure that an attacker can't escape the # query and fake the login (or worse). # # When using multiple parameters in the conditions, it can easily become hard to read exactly # what the fourth or fifth question mark is supposed to represent. In those cases, you can # resort to named bind variables instead. That's done by replacing the question marks with # symbols and supplying a hash with values for the matching symbol keys: # # Company.where( # "id = :id AND name = :name AND division = :division AND created_at > :accounting_date", # { id: 3, name: "37signals", division: "First", accounting_date: '2005-01-01' } # ).first # # Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND # operator. For instance: # # Student.where(first_name: "Harvey", status: 1) # Student.where(params[:student]) # # A range may be used in the hash to use the SQL BETWEEN operator: # # Student.where(grade: 9..12) # # An array may be used in the hash to use the SQL IN operator: # # Student.where(grade: [9,11,12]) # # When joining tables, nested hashes or keys written in the form 'table_name.column_name' # can be used to qualify the table name of a particular condition. For instance: # # Student.joins(:schools).where(schools: { category: 'public' }) # Student.joins(:schools).where('schools.category' => 'public' ) # # == Overwriting default accessors # # All column values are automatically available through basic accessors on the Active Record # object, but sometimes you want to specialize this behavior. This can be done by overwriting # the default accessors (using the same name as the attribute) and calling # read_attribute(attr_name) and write_attribute(attr_name, value) to actually # change things. # # class Song < ActiveRecord::Base # # Uses an integer of seconds to hold the length of the song # # def length=(minutes) # write_attribute(:length, minutes.to_i * 60) # end # # def length # read_attribute(:length) / 60 # end # end # # You can alternatively use self[:attribute]=(value) and self[:attribute] # instead of write_attribute(:attribute, value) and read_attribute(:attribute). # # == Attribute query methods # # In addition to the basic accessors, query methods are also automatically available on the Active Record object. # Query methods allow you to test whether an attribute value is present. # # For example, an Active Record User with the name attribute has a name? method that you can call # to determine whether the user has a name: # # user = User.new(name: "David") # user.name? # => true # # anonymous = User.new(name: "") # anonymous.name? # => false # # == Accessing attributes before they have been typecasted # # Sometimes you want to be able to read the raw attribute data without having the column-determined # typecast run its course first. That can be done by using the _before_type_cast # accessors that all attributes have. For example, if your Account model has a balance attribute, # you can call account.balance_before_type_cast or account.id_before_type_cast. # # This is especially useful in validation situations where the user might supply a string for an # integer field and you want to display the original string back in an error message. Accessing the # attribute normally would typecast the string to 0, which isn't what you want. # # == Dynamic attribute-based finders # # Dynamic attribute-based finders are a mildly deprecated way of getting (and/or creating) objects # by simple queries without turning to SQL. They work by appending the name of an attribute # to find_by_ like Person.find_by_user_name. # Instead of writing Person.find_by(user_name: user_name), you can use # Person.find_by_user_name(user_name). # # It's possible to add an exclamation point (!) on the end of the dynamic finders to get them to raise an # ActiveRecord::RecordNotFound error if they do not return any records, # like Person.find_by_last_name!. # # It's also possible to use multiple attributes in the same find by separating them with "_and_". # # Person.find_by(user_name: user_name, password: password) # Person.find_by_user_name_and_password(user_name, password) # with dynamic finder # # It's even possible to call these dynamic finder methods on relations and named scopes. # # Payment.order("created_on").find_by_amount(50) # # == Saving arrays, hashes, and other non-mappable objects in text columns # # Active Record can serialize any object in text columns using YAML. To do so, you must # specify this with a call to the class method +serialize+. # This makes it possible to store arrays, hashes, and other non-mappable objects without doing # any additional work. # # class User < ActiveRecord::Base # serialize :preferences # end # # user = User.create(preferences: { "background" => "black", "display" => large }) # User.find(user.id).preferences # => { "background" => "black", "display" => large } # # You can also specify a class option as the second parameter that'll raise an exception # if a serialized object is retrieved as a descendant of a class not in the hierarchy. # # class User < ActiveRecord::Base # serialize :preferences, Hash # end # # user = User.create(preferences: %w( one two three )) # User.find(user.id).preferences # raises SerializationTypeMismatch # # When you specify a class option, the default value for that attribute will be a new # instance of that class. # # class User < ActiveRecord::Base # serialize :preferences, OpenStruct # end # # user = User.new # user.preferences.theme_color = "red" # # # == Single table inheritance # # Active Record allows inheritance by storing the name of the class in a column that by # default is named "type" (can be changed by overwriting Base.inheritance_column). # This means that an inheritance looking like this: # # class Company < ActiveRecord::Base; end # class Firm < Company; end # class Client < Company; end # class PriorityClient < Client; end # # When you do Firm.create(name: "37signals"), this record will be saved in # the companies table with type = "Firm". You can then fetch this row again using # Company.where(name: '37signals').first and it will return a Firm object. # # If you don't have a type column defined in your table, single-table inheritance won't # be triggered. In that case, it'll work just like normal subclasses with no special magic # for differentiating between them or reloading the right type with find. # # Note, all the attributes for all the cases are kept in the same table. Read more: # http://www.martinfowler.com/eaaCatalog/singleTableInheritance.html # # == Connection to multiple databases in different models # # Connections are usually created through ActiveRecord::Base.establish_connection and retrieved # by ActiveRecord::Base.connection. All classes inheriting from ActiveRecord::Base will use this # connection. But you can also set a class-specific connection. For example, if Course is an # ActiveRecord::Base, but resides in a different database, you can just say Course.establish_connection # and Course and all of its subclasses will use this connection instead. # # This feature is implemented by keeping a connection pool in ActiveRecord::Base that is # a Hash indexed by the class. If a connection is requested, the retrieve_connection method # will go up the class-hierarchy until a connection is found in the connection pool. # # == Exceptions # # * ActiveRecordError - Generic error class and superclass of all other errors raised by Active Record. # * AdapterNotSpecified - The configuration hash used in establish_connection didn't include an # :adapter key. # * AdapterNotFound - The :adapter key used in establish_connection specified a # non-existent adapter # (or a bad spelling of an existing one). # * AssociationTypeMismatch - The object assigned to the association wasn't of the type # specified in the association definition. # * AttributeAssignmentError - An error occurred while doing a mass assignment through the # attributes= method. # You can inspect the +attribute+ property of the exception object to determine which attribute # triggered the error. # * ConnectionNotEstablished - No connection has been established. Use establish_connection # before querying. # * MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the # attributes= method. The +errors+ property of this exception contains an array of # AttributeAssignmentError # objects that should be inspected to determine which attributes triggered the errors. # * RecordInvalid - raised by save! and create! when the record is invalid. # * RecordNotFound - No record responded to the +find+ method. Either the row with the given ID doesn't exist # or the row didn't meet the additional restrictions. Some +find+ calls do not raise this exception to signal # nothing was found, please check its documentation for further details. # * SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter. # * StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message. # # *Note*: The attributes listed are class-level attributes (accessible from both the class and instance level). # So it's possible to assign a logger to the class through Base.logger= which will then be used by all # instances in the current object space. class Base extend ActiveModel::Naming extend ActiveSupport::Benchmarkable extend ActiveSupport::DescendantsTracker extend ConnectionHandling extend QueryCache::ClassMethods extend Querying extend Translation extend DynamicMatchers extend Explain include Persistence include ReadonlyAttributes include ModelSchema include Inheritance include Scoping include Sanitization include AttributeAssignment include ActiveModel::Conversion include Integration include Validations include CounterCache include Locking::Optimistic include Locking::Pessimistic include AttributeMethods include Timestamp include Callbacks include Associations include ActiveModel::SecurePassword include AutosaveAssociation include NestedAttributes include Aggregations include Transactions include Reflection include Serialization include Store include Core end ActiveSupport.run_load_hooks(:active_record, Base) end