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base.rb
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base.rb
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require 'yaml'
require 'set'
require 'active_support/dependencies'
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/class/inheritable_attributes'
require 'active_support/core_ext/array/extract_options'
require 'active_support/core_ext/hash/deep_merge'
require 'active_support/core_ext/hash/indifferent_access'
require 'active_support/core_ext/hash/slice'
require 'active_support/core_ext/string/behavior'
require 'active_support/core_ext/symbol'
require 'active_support/core_ext/object/metaclass'
module ActiveRecord #:nodoc:
# Generic Active Record exception class.
class ActiveRecordError < StandardError
end
# Raised when the single-table inheritance mechanism fails to locate the subclass
# (for example due to improper usage of column that +inheritance_column+ points to).
class SubclassNotFound < ActiveRecordError #:nodoc:
end
# Raised when an object assigned to an association has an incorrect type.
#
# class Ticket < ActiveRecord::Base
# has_many :patches
# end
#
# class Patch < ActiveRecord::Base
# belongs_to :ticket
# end
#
# # Comments are not patches, this assignment raises AssociationTypeMismatch.
# @ticket.patches << Comment.new(:content => "Please attach tests to your patch.")
class AssociationTypeMismatch < ActiveRecordError
end
# Raised when unserialized object's type mismatches one specified for serializable field.
class SerializationTypeMismatch < ActiveRecordError
end
# Raised when adapter not specified on connection (or configuration file <tt>config/database.yml</tt> misses adapter field).
class AdapterNotSpecified < ActiveRecordError
end
# Raised when Active Record cannot find database adapter specified in <tt>config/database.yml</tt> or programmatically.
class AdapterNotFound < ActiveRecordError
end
# Raised when connection to the database could not been established (for example when <tt>connection=</tt> is given a nil object).
class ConnectionNotEstablished < ActiveRecordError
end
# Raised when Active Record cannot find record by given id or set of ids.
class RecordNotFound < ActiveRecordError
end
# Raised by ActiveRecord::Base.save! and ActiveRecord::Base.create! methods when record cannot be
# saved because record is invalid.
class RecordNotSaved < ActiveRecordError
end
# Raised when SQL statement cannot be executed by the database (for example, it's often the case for MySQL when Ruby driver used is too old).
class StatementInvalid < ActiveRecordError
end
# Parent class for all specific exceptions which wrap database driver exceptions
# provides access to the original exception also.
class WrappedDatabaseException < StatementInvalid
attr_reader :original_exception
def initialize(message, original_exception)
super(message)
@original_exception, = original_exception
end
end
# Raised when a record cannot be inserted because it would violate a uniqueness constraint.
class RecordNotUnique < WrappedDatabaseException
end
# Raised when a record cannot be inserted or updated because it references a non-existent record.
class InvalidForeignKey < WrappedDatabaseException
end
# Raised when number of bind variables in statement given to <tt>:condition</tt> key (for example, when using +find+ method)
# does not match number of expected variables.
#
# For example, in
#
# Location.find :all, :conditions => ["lat = ? AND lng = ?", 53.7362]
#
# two placeholders are given but only one variable to fill them.
class PreparedStatementInvalid < ActiveRecordError
end
# Raised on attempt to save stale record. Record is stale when it's being saved in another query after
# instantiation, for example, when two users edit the same wiki page and one starts editing and saves
# the page before the other.
#
# Read more about optimistic locking in ActiveRecord::Locking module RDoc.
class StaleObjectError < ActiveRecordError
end
# Raised when association is being configured improperly or
# user tries to use offset and limit together with has_many or has_and_belongs_to_many associations.
class ConfigurationError < ActiveRecordError
end
# Raised on attempt to update record that is instantiated as read only.
class ReadOnlyRecord < ActiveRecordError
end
# ActiveRecord::Transactions::ClassMethods.transaction uses this exception
# to distinguish a deliberate rollback from other exceptional situations.
# Normally, raising an exception will cause the +transaction+ method to rollback
# the database transaction *and* pass on the exception. But if you raise an
# ActiveRecord::Rollback exception, then the database transaction will be rolled back,
# without passing on the exception.
#
# For example, you could do this in your controller to rollback a transaction:
#
# class BooksController < ActionController::Base
# def create
# Book.transaction do
# book = Book.new(params[:book])
# book.save!
# if today_is_friday?
# # The system must fail on Friday so that our support department
# # won't be out of job. We silently rollback this transaction
# # without telling the user.
# raise ActiveRecord::Rollback, "Call tech support!"
# end
# end
# # ActiveRecord::Rollback is the only exception that won't be passed on
# # by ActiveRecord::Base.transaction, so this line will still be reached
# # even on Friday.
# redirect_to root_url
# end
# end
class Rollback < ActiveRecordError
end
# Raised when attribute has a name reserved by Active Record (when attribute has name of one of Active Record instance methods).
class DangerousAttributeError < ActiveRecordError
end
# Raised when unknown attributes are supplied via mass assignment.
class UnknownAttributeError < NoMethodError
end
# Raised when an error occurred while doing a mass assignment to an attribute through the
# <tt>attributes=</tt> method. The exception has an +attribute+ property that is the name of the
# offending attribute.
class AttributeAssignmentError < ActiveRecordError
attr_reader :exception, :attribute
def initialize(message, exception, attribute)
@exception = exception
@attribute = attribute
@message = message
end
end
# Raised when there are multiple errors while doing a mass assignment through the +attributes+
# method. The exception has an +errors+ property that contains an array of AttributeAssignmentError
# objects, each corresponding to the error while assigning to an attribute.
class MultiparameterAssignmentErrors < ActiveRecordError
attr_reader :errors
def initialize(errors)
@errors = errors
end
end
# 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/README.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)
# find(:first, :conditions => "user_name = '#{user_name}' AND password = '#{password}'")
# end
#
# def self.authenticate_safely(user_name, password)
# find(:first, :conditions => [ "user_name = ? AND password = ?", user_name, password ])
# end
#
# def self.authenticate_safely_simply(user_name, password)
# find(:first, :conditions => { :user_name => user_name, :password => password })
# end
# end
#
# The <tt>authenticate_unsafely</tt> method inserts the parameters directly into the query and is thus susceptible to SQL-injection
# attacks if the <tt>user_name</tt> and +password+ parameters come directly from an HTTP request. The <tt>authenticate_safely</tt> and
# <tt>authenticate_safely_simply</tt> both will sanitize the <tt>user_name</tt> 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.find(:first, :conditions => [
# "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
# { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
# ])
#
# Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND
# operator. For instance:
#
# Student.find(:all, :conditions => { :first_name => "Harvey", :status => 1 })
# Student.find(:all, :conditions => params[:student])
#
# A range may be used in the hash to use the SQL BETWEEN operator:
#
# Student.find(:all, :conditions => { :grade => 9..12 })
#
# An array may be used in the hash to use the SQL IN operator:
#
# Student.find(:all, :conditions => { :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.find(:all, :conditions => { :schools => { :type => 'public' }}, :joins => :schools)
# Student.find(:all, :conditions => { 'schools.type' => 'public' }, :joins => :schools)
#
# == 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 <tt>read_attribute(attr_name)</tt> and <tt>write_attribute(attr_name, value)</tt> to actually change things.
# Example:
#
# 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 <tt>self[:attribute]=(value)</tt> and <tt>self[:attribute]</tt> instead of <tt>write_attribute(:attribute, value)</tt> and
# <tt>read_attribute(:attribute)</tt> as a shorter form.
#
# == 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 <tt>name</tt> attribute has a <tt>name?</tt> 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 <tt><attribute>_before_type_cast</tt> accessors that all attributes have. For example, if your Account model
# has a <tt>balance</tt> attribute, you can call <tt>account.balance_before_type_cast</tt> or <tt>account.id_before_type_cast</tt>.
#
# 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 cleaner way of getting (and/or creating) objects by simple queries without turning to SQL. They work by
# appending the name of an attribute to <tt>find_by_</tt>, <tt>find_last_by_</tt>, or <tt>find_all_by_</tt>, so you get finders like <tt>Person.find_by_user_name</tt>,
# <tt>Person.find_all_by_last_name</tt>, and <tt>Payment.find_by_transaction_id</tt>. So instead of writing
# <tt>Person.find(:first, :conditions => ["user_name = ?", user_name])</tt>, you just do <tt>Person.find_by_user_name(user_name)</tt>.
# And instead of writing <tt>Person.find(:all, :conditions => ["last_name = ?", last_name])</tt>, you just do <tt>Person.find_all_by_last_name(last_name)</tt>.
#
# It's also possible to use multiple attributes in the same find by separating them with "_and_", so you get finders like
# <tt>Person.find_by_user_name_and_password</tt> or even <tt>Payment.find_by_purchaser_and_state_and_country</tt>. So instead of writing
# <tt>Person.find(:first, :conditions => ["user_name = ? AND password = ?", user_name, password])</tt>, you just do
# <tt>Person.find_by_user_name_and_password(user_name, password)</tt>.
#
# It's even possible to use all the additional parameters to find. For example, the full interface for <tt>Payment.find_all_by_amount</tt>
# is actually <tt>Payment.find_all_by_amount(amount, options)</tt>. And the full interface to <tt>Person.find_by_user_name</tt> is
# actually <tt>Person.find_by_user_name(user_name, options)</tt>. So you could call <tt>Payment.find_all_by_amount(50, :order => "created_on")</tt>.
# Also you may call <tt>Payment.find_last_by_amount(amount, options)</tt> returning the last record matching that amount and options.
#
# The same dynamic finder style can be used to create the object if it doesn't already exist. This dynamic finder is called with
# <tt>find_or_create_by_</tt> and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won't be set unless they are given in a block. For example:
#
# # No 'Summer' tag exists
# Tag.find_or_create_by_name("Summer") # equal to Tag.create(:name => "Summer")
#
# # Now the 'Summer' tag does exist
# Tag.find_or_create_by_name("Summer") # equal to Tag.find_by_name("Summer")
#
# # Now 'Bob' exist and is an 'admin'
# User.find_or_create_by_name('Bob', :age => 40) { |u| u.admin = true }
#
# Use the <tt>find_or_initialize_by_</tt> finder if you want to return a new record without saving it first. Protected attributes won't be set unless they are given in a block. For example:
#
# # No 'Winter' tag exists
# winter = Tag.find_or_initialize_by_name("Winter")
# winter.new_record? # true
#
# To find by a subset of the attributes to be used for instantiating a new object, pass a hash instead of
# a list of parameters. For example:
#
# Tag.find_or_create_by_name(:name => "rails", :creator => current_user)
#
# That will either find an existing tag named "rails", or create a new one while setting the user that created it.
#
# == 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. Example:
#
# 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. Example:
#
# class User < ActiveRecord::Base
# serialize :preferences, Hash
# end
#
# user = User.create(:preferences => %w( one two three ))
# User.find(user.id).preferences # raises SerializationTypeMismatch
#
# == 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 <tt>Base.inheritance_column</tt>). 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 <tt>Firm.create(:name => "37signals")</tt>, this record will be saved in the companies table with type = "Firm". You can then
# fetch this row again using <tt>Company.find(:first, "name = '37signals'")</tt> 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 <tt>Course.establish_connection</tt>
# 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 <tt>establish_connection</tt> didn't include an
# <tt>:adapter</tt> key.
# * AdapterNotFound - The <tt>:adapter</tt> key used in <tt>establish_connection</tt> 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.
# * SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.
# * ConnectionNotEstablished+ - No connection has been established. Use <tt>establish_connection</tt> before querying.
# * 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.
# * StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.
# * MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the
# <tt>attributes=</tt> method. The +errors+ property of this exception contains an array of AttributeAssignmentError
# objects that should be inspected to determine which attributes triggered the errors.
# * AttributeAssignmentError - An error occurred while doing a mass assignment through the <tt>attributes=</tt> method.
# You can inspect the +attribute+ property of the exception object to determine which attribute triggered the error.
#
# *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 <tt>Base.logger=</tt> which will then be used by all
# instances in the current object space.
class Base
##
# :singleton-method:
# Accepts a logger conforming to the interface of Log4r or the default Ruby 1.8+ Logger class, which is then passed
# on to any new database connections made and which can be retrieved on both a class and instance level by calling +logger+.
cattr_accessor :logger, :instance_writer => false
def self.inherited(child) #:nodoc:
@@subclasses[self] ||= []
@@subclasses[self] << child
super
end
def self.reset_subclasses #:nodoc:
nonreloadables = []
subclasses.each do |klass|
unless ActiveSupport::Dependencies.autoloaded? klass
nonreloadables << klass
next
end
klass.instance_variables.each { |var| klass.send(:remove_instance_variable, var) }
klass.instance_methods(false).each { |m| klass.send :undef_method, m }
end
@@subclasses = {}
nonreloadables.each { |klass| (@@subclasses[klass.superclass] ||= []) << klass }
end
@@subclasses = {}
##
# :singleton-method:
# Contains the database configuration - as is typically stored in config/database.yml -
# as a Hash.
#
# For example, the following database.yml...
#
# development:
# adapter: sqlite3
# database: db/development.sqlite3
#
# production:
# adapter: sqlite3
# database: db/production.sqlite3
#
# ...would result in ActiveRecord::Base.configurations to look like this:
#
# {
# 'development' => {
# 'adapter' => 'sqlite3',
# 'database' => 'db/development.sqlite3'
# },
# 'production' => {
# 'adapter' => 'sqlite3',
# 'database' => 'db/production.sqlite3'
# }
# }
cattr_accessor :configurations, :instance_writer => false
@@configurations = {}
##
# :singleton-method:
# Accessor for the prefix type that will be prepended to every primary key column name. The options are :table_name and
# :table_name_with_underscore. If the first is specified, the Product class will look for "productid" instead of "id" as
# the primary column. If the latter is specified, the Product class will look for "product_id" instead of "id". Remember
# that this is a global setting for all Active Records.
cattr_accessor :primary_key_prefix_type, :instance_writer => false
@@primary_key_prefix_type = nil
##
# :singleton-method:
# Accessor for the name of the prefix string to prepend to every table name. So if set to "basecamp_", all
# table names will be named like "basecamp_projects", "basecamp_people", etc. This is a convenient way of creating a namespace
# for tables in a shared database. By default, the prefix is the empty string.
cattr_accessor :table_name_prefix, :instance_writer => false
@@table_name_prefix = ""
##
# :singleton-method:
# Works like +table_name_prefix+, but appends instead of prepends (set to "_basecamp" gives "projects_basecamp",
# "people_basecamp"). By default, the suffix is the empty string.
cattr_accessor :table_name_suffix, :instance_writer => false
@@table_name_suffix = ""
##
# :singleton-method:
# Indicates whether table names should be the pluralized versions of the corresponding class names.
# If true, the default table name for a Product class will be +products+. If false, it would just be +product+.
# See table_name for the full rules on table/class naming. This is true, by default.
cattr_accessor :pluralize_table_names, :instance_writer => false
@@pluralize_table_names = true
##
# :singleton-method:
# Determines whether to use ANSI codes to colorize the logging statements committed by the connection adapter. These colors
# make it much easier to overview things during debugging (when used through a reader like +tail+ and on a black background), but
# may complicate matters if you use software like syslog. This is true, by default.
cattr_accessor :colorize_logging, :instance_writer => false
@@colorize_logging = true
##
# :singleton-method:
# Determines whether to use Time.local (using :local) or Time.utc (using :utc) when pulling dates and times from the database.
# This is set to :local by default.
cattr_accessor :default_timezone, :instance_writer => false
@@default_timezone = :local
##
# :singleton-method:
# Specifies the format to use when dumping the database schema with Rails'
# Rakefile. If :sql, the schema is dumped as (potentially database-
# specific) SQL statements. If :ruby, the schema is dumped as an
# ActiveRecord::Schema file which can be loaded into any database that
# supports migrations. Use :ruby if you want to have different database
# adapters for, e.g., your development and test environments.
cattr_accessor :schema_format , :instance_writer => false
@@schema_format = :ruby
##
# :singleton-method:
# Specify whether or not to use timestamps for migration numbers
cattr_accessor :timestamped_migrations , :instance_writer => false
@@timestamped_migrations = true
# Determine whether to store the full constant name including namespace when using STI
superclass_delegating_accessor :store_full_sti_class
self.store_full_sti_class = false
# Stores the default scope for the class
class_inheritable_accessor :default_scoping, :instance_writer => false
self.default_scoping = []
class << self # Class methods
# Find operates with four different retrieval approaches:
#
# * Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]).
# If no record can be found for all of the listed ids, then RecordNotFound will be raised.
# * Find first - This will return the first record matched by the options used. These options can either be specific
# conditions or merely an order. If no record can be matched, +nil+ is returned. Use
# <tt>Model.find(:first, *args)</tt> or its shortcut <tt>Model.first(*args)</tt>.
# * Find last - This will return the last record matched by the options used. These options can either be specific
# conditions or merely an order. If no record can be matched, +nil+ is returned. Use
# <tt>Model.find(:last, *args)</tt> or its shortcut <tt>Model.last(*args)</tt>.
# * Find all - This will return all the records matched by the options used.
# If no records are found, an empty array is returned. Use
# <tt>Model.find(:all, *args)</tt> or its shortcut <tt>Model.all(*args)</tt>.
#
# All approaches accept an options hash as their last parameter.
#
# ==== Parameters
#
# * <tt>:conditions</tt> - An SQL fragment like "administrator = 1", <tt>[ "user_name = ?", username ]</tt>, or <tt>["user_name = :user_name", { :user_name => user_name }]</tt>. See conditions in the intro.
# * <tt>:order</tt> - An SQL fragment like "created_at DESC, name".
# * <tt>:group</tt> - An attribute name by which the result should be grouped. Uses the <tt>GROUP BY</tt> SQL-clause.
# * <tt>:having</tt> - Combined with +:group+ this can be used to filter the records that a <tt>GROUP BY</tt> returns. Uses the <tt>HAVING</tt> SQL-clause.
# * <tt>:limit</tt> - An integer determining the limit on the number of rows that should be returned.
# * <tt>:offset</tt> - An integer determining the offset from where the rows should be fetched. So at 5, it would skip rows 0 through 4.
# * <tt>:joins</tt> - Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id" (rarely needed),
# named associations in the same form used for the <tt>:include</tt> option, which will perform an <tt>INNER JOIN</tt> on the associated table(s),
# or an array containing a mixture of both strings and named associations.
# If the value is a string, then the records will be returned read-only since they will have attributes that do not correspond to the table's columns.
# Pass <tt>:readonly => false</tt> to override.
# * <tt>:include</tt> - Names associations that should be loaded alongside. The symbols named refer
# to already defined associations. See eager loading under Associations.
# * <tt>:select</tt> - By default, this is "*" as in "SELECT * FROM", but can be changed if you, for example, want to do a join but not
# include the joined columns. Takes a string with the SELECT SQL fragment (e.g. "id, name").
# * <tt>:from</tt> - By default, this is the table name of the class, but can be changed to an alternate table name (or even the name
# of a database view).
# * <tt>:readonly</tt> - Mark the returned records read-only so they cannot be saved or updated.
# * <tt>:lock</tt> - An SQL fragment like "FOR UPDATE" or "LOCK IN SHARE MODE".
# <tt>:lock => true</tt> gives connection's default exclusive lock, usually "FOR UPDATE".
#
# ==== Examples
#
# # find by id
# Person.find(1) # returns the object for ID = 1
# Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6)
# Person.find([7, 17]) # returns an array for objects with IDs in (7, 17)
# Person.find([1]) # returns an array for the object with ID = 1
# Person.find(1, :conditions => "administrator = 1", :order => "created_on DESC")
#
# Note that returned records may not be in the same order as the ids you
# provide since database rows are unordered. Give an explicit <tt>:order</tt>
# to ensure the results are sorted.
#
# ==== Examples
#
# # find first
# Person.find(:first) # returns the first object fetched by SELECT * FROM people
# Person.find(:first, :conditions => [ "user_name = ?", user_name])
# Person.find(:first, :conditions => [ "user_name = :u", { :u => user_name }])
# Person.find(:first, :order => "created_on DESC", :offset => 5)
#
# # find last
# Person.find(:last) # returns the last object fetched by SELECT * FROM people
# Person.find(:last, :conditions => [ "user_name = ?", user_name])
# Person.find(:last, :order => "created_on DESC", :offset => 5)
#
# # find all
# Person.find(:all) # returns an array of objects for all the rows fetched by SELECT * FROM people
# Person.find(:all, :conditions => [ "category IN (?)", categories], :limit => 50)
# Person.find(:all, :conditions => { :friends => ["Bob", "Steve", "Fred"] }
# Person.find(:all, :offset => 10, :limit => 10)
# Person.find(:all, :include => [ :account, :friends ])
# Person.find(:all, :group => "category")
#
# Example for find with a lock: Imagine two concurrent transactions:
# each will read <tt>person.visits == 2</tt>, add 1 to it, and save, resulting
# in two saves of <tt>person.visits = 3</tt>. By locking the row, the second
# transaction has to wait until the first is finished; we get the
# expected <tt>person.visits == 4</tt>.
#
# Person.transaction do
# person = Person.find(1, :lock => true)
# person.visits += 1
# person.save!
# end
def find(*args)
options = args.extract_options!
validate_find_options(options)
set_readonly_option!(options)
case args.first
when :first then find_initial(options)
when :last then find_last(options)
when :all then find_every(options)
else find_from_ids(args, options)
end
end
# A convenience wrapper for <tt>find(:first, *args)</tt>. You can pass in all the
# same arguments to this method as you can to <tt>find(:first)</tt>.
def first(*args)
find(:first, *args)
end
# A convenience wrapper for <tt>find(:last, *args)</tt>. You can pass in all the
# same arguments to this method as you can to <tt>find(:last)</tt>.
def last(*args)
find(:last, *args)
end
# This is an alias for find(:all). You can pass in all the same arguments to this method as you can
# to find(:all)
def all(*args)
if args.empty? && !scoped?(:find)
arel_table
else
construct_finder_arel(*args)
end
end
# Executes a custom SQL query against your database and returns all the results. The results will
# be returned as an array with columns requested encapsulated as attributes of the model you call
# this method from. If you call <tt>Product.find_by_sql</tt> then the results will be returned in
# a Product object with the attributes you specified in the SQL query.
#
# If you call a complicated SQL query which spans multiple tables the columns specified by the
# SELECT will be attributes of the model, whether or not they are columns of the corresponding
# table.
#
# The +sql+ parameter is a full SQL query as a string. It will be called as is, there will be
# no database agnostic conversions performed. This should be a last resort because using, for example,
# MySQL specific terms will lock you to using that particular database engine or require you to
# change your call if you switch engines.
#
# ==== Examples
# # A simple SQL query spanning multiple tables
# Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id"
# > [#<Post:0x36bff9c @attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...]
#
# # You can use the same string replacement techniques as you can with ActiveRecord#find
# Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date]
# > [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]
def find_by_sql(sql)
connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
end
# Returns true if a record exists in the table that matches the +id+ or
# conditions given, or false otherwise. The argument can take five forms:
#
# * Integer - Finds the record with this primary key.
# * String - Finds the record with a primary key corresponding to this
# string (such as <tt>'5'</tt>).
# * Array - Finds the record that matches these +find+-style conditions
# (such as <tt>['color = ?', 'red']</tt>).
# * Hash - Finds the record that matches these +find+-style conditions
# (such as <tt>{:color => 'red'}</tt>).
# * No args - Returns false if the table is empty, true otherwise.
#
# For more information about specifying conditions as a Hash or Array,
# see the Conditions section in the introduction to ActiveRecord::Base.
#
# Note: You can't pass in a condition as a string (like <tt>name =
# 'Jamie'</tt>), since it would be sanitized and then queried against
# the primary key column, like <tt>id = 'name = \'Jamie\''</tt>.
#
# ==== Examples
# Person.exists?(5)
# Person.exists?('5')
# Person.exists?(:name => "David")
# Person.exists?(['name LIKE ?', "%#{query}%"])
# Person.exists?
def exists?(id_or_conditions = {})
find_initial(
:select => "#{quoted_table_name}.#{primary_key}",
:conditions => expand_id_conditions(id_or_conditions)) ? true : false
end
# Creates an object (or multiple objects) and saves it to the database, if validations pass.
# The resulting object is returned whether the object was saved successfully to the database or not.
#
# The +attributes+ parameter can be either be a Hash or an Array of Hashes. These Hashes describe the
# attributes on the objects that are to be created.
#
# ==== Examples
# # Create a single new object
# User.create(:first_name => 'Jamie')
#
# # Create an Array of new objects
# User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }])
#
# # Create a single object and pass it into a block to set other attributes.
# User.create(:first_name => 'Jamie') do |u|
# u.is_admin = false
# end
#
# # Creating an Array of new objects using a block, where the block is executed for each object:
# User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u|
# u.is_admin = false
# end
def create(attributes = nil, &block)
if attributes.is_a?(Array)
attributes.collect { |attr| create(attr, &block) }
else
object = new(attributes)
yield(object) if block_given?
object.save
object
end
end
# Updates an object (or multiple objects) and saves it to the database, if validations pass.
# The resulting object is returned whether the object was saved successfully to the database or not.
#
# ==== Parameters
#
# * +id+ - This should be the id or an array of ids to be updated.
# * +attributes+ - This should be a hash of attributes to be set on the object, or an array of hashes.
#
# ==== Examples
#
# # Updating one record:
# Person.update(15, :user_name => 'Samuel', :group => 'expert')
#
# # Updating multiple records:
# people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
# Person.update(people.keys, people.values)
def update(id, attributes)
if id.is_a?(Array)
idx = -1
id.collect { |one_id| idx += 1; update(one_id, attributes[idx]) }
else
object = find(id)
object.update_attributes(attributes)
object
end
end
# Deletes the row with a primary key matching the +id+ argument, using a
# SQL +DELETE+ statement, and returns the number of rows deleted. Active
# Record objects are not instantiated, so the object's callbacks are not
# executed, including any <tt>:dependent</tt> association options or
# Observer methods.
#
# You can delete multiple rows at once by passing an Array of <tt>id</tt>s.
#
# Note: Although it is often much faster than the alternative,
# <tt>#destroy</tt>, skipping callbacks might bypass business logic in
# your application that ensures referential integrity or performs other
# essential jobs.
#
# ==== Examples
#
# # Delete a single row
# Todo.delete(1)
#
# # Delete multiple rows
# Todo.delete([2,3,4])
def delete(id)
delete_all([ "#{connection.quote_column_name(primary_key)} IN (?)", id ])
end
# Destroy an object (or multiple objects) that has the given id, the object is instantiated first,
# therefore all callbacks and filters are fired off before the object is deleted. This method is
# less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.
#
# This essentially finds the object (or multiple objects) with the given id, creates a new object
# from the attributes, and then calls destroy on it.
#
# ==== Parameters
#
# * +id+ - Can be either an Integer or an Array of Integers.
#
# ==== Examples
#
# # Destroy a single object
# Todo.destroy(1)
#
# # Destroy multiple objects
# todos = [1,2,3]
# Todo.destroy(todos)
def destroy(id)
if id.is_a?(Array)
id.map { |one_id| destroy(one_id) }
else
find(id).destroy
end
end
# Updates all records with details given if they match a set of conditions supplied, limits and order can
# also be supplied. This method constructs a single SQL UPDATE statement and sends it straight to the
# database. It does not instantiate the involved models and it does not trigger Active Record callbacks
# or validations.
#
# ==== Parameters
#
# * +updates+ - A string, array, or hash representing the SET part of an SQL statement.
# * +conditions+ - A string, array, or hash representing the WHERE part of an SQL statement. See conditions in the intro.
# * +options+ - Additional options are <tt>:limit</tt> and <tt>:order</tt>, see the examples for usage.
#
# ==== Examples
#
# # Update all customers with the given attributes
# Customer.update_all :wants_email => true
#
# # Update all books with 'Rails' in their title
# Book.update_all "author = 'David'", "title LIKE '%Rails%'"
#
# # Update all avatars migrated more than a week ago
# Avatar.update_all ['migrated_at = ?', Time.now.utc], ['migrated_at > ?', 1.week.ago]
#
# # Update all books that match our conditions, but limit it to 5 ordered by date
# Book.update_all "author = 'David'", "title LIKE '%Rails%'", :order => 'created_at', :limit => 5
def update_all(updates, conditions = nil, options = {})
scope = scope(:find)
relation = arel_table.relation
if conditions = construct_conditions(conditions, scope)
relation = relation.where(Arel::SqlLiteral.new(conditions))
end
if options.has_key?(:limit) || (scope && scope[:limit])
# Only take order from scope if limit is also provided by scope, this
# is useful for updating a has_many association with a limit.
relation = relation.order(construct_order(options[:order], scope)).take(construct_limit(options[:limit], scope))
else
relation = relation.order(construct_order(options[:order], nil))
end
relation.update(sanitize_sql_for_assignment(updates))
end
# Destroys the records matching +conditions+ by instantiating each
# record and calling its +destroy+ method. Each object's callbacks are
# executed (including <tt>:dependent</tt> association options and
# +before_destroy+/+after_destroy+ Observer methods). Returns the
# collection of objects that were destroyed; each will be frozen, to
# reflect that no changes should be made (since they can't be
# persisted).
#
# Note: Instantiation, callback execution, and deletion of each
# record can be time consuming when you're removing many records at
# once. It generates at least one SQL +DELETE+ query per record (or
# possibly more, to enforce your callbacks). If you want to delete many
# rows quickly, without concern for their associations or callbacks, use
# +delete_all+ instead.
#
# ==== Parameters
#
# * +conditions+ - A string, array, or hash that specifies which records
# to destroy. If omitted, all records are destroyed. See the
# Conditions section in the introduction to ActiveRecord::Base for
# more information.
#
# ==== Examples
#
# Person.destroy_all("last_login < '2004-04-04'")
# Person.destroy_all(:status => "inactive")
def destroy_all(conditions = nil)
find(:all, :conditions => conditions).each { |object| object.destroy }
end
# Deletes the records matching +conditions+ without instantiating the records first, and hence not
# calling the +destroy+ method nor invoking callbacks. This is a single SQL DELETE statement that
# goes straight to the database, much more efficient than +destroy_all+. Be careful with relations
# though, in particular <tt>:dependent</tt> rules defined on associations are not honored. Returns
# the number of rows affected.
#
# ==== Parameters
#
# * +conditions+ - Conditions are specified the same way as with +find+ method.
#
# ==== Example
#
# Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')")
# Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])
#
# Both calls delete the affected posts all at once with a single DELETE statement. If you need to destroy dependent
# associations or call your <tt>before_*</tt> or +after_destroy+ callbacks, use the +destroy_all+ method instead.
def delete_all(conditions = nil)
if conditions
arel_table.where(Arel::SqlLiteral.new(construct_conditions(conditions, scope(:find)))).delete
else
arel_table.delete
end
end
# Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part.
# The use of this method should be restricted to complicated SQL queries that can't be executed
# using the ActiveRecord::Calculations class methods. Look into those before using this.
#
# ==== Parameters
#
# * +sql+ - An SQL statement which should return a count query from the database, see the example below.
#
# ==== Examples
#
# Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
def count_by_sql(sql)
sql = sanitize_conditions(sql)
connection.select_value(sql, "#{name} Count").to_i
end
# A generic "counter updater" implementation, intended primarily to be
# used by increment_counter and decrement_counter, but which may also
# be useful on its own. It simply does a direct SQL update for the record
# with the given ID, altering the given hash of counters by the amount
# given by the corresponding value:
#
# ==== Parameters
#
# * +id+ - The id of the object you wish to update a counter on or an Array of ids.
# * +counters+ - An Array of Hashes containing the names of the fields
# to update as keys and the amount to update the field by as values.
#
# ==== Examples
#
# # For the Post with id of 5, decrement the comment_count by 1, and
# # increment the action_count by 1
# Post.update_counters 5, :comment_count => -1, :action_count => 1
# # Executes the following SQL:
# # UPDATE posts
# # SET comment_count = comment_count - 1,
# # action_count = action_count + 1
# # WHERE id = 5
#
# # For the Posts with id of 10 and 15, increment the comment_count by 1
# Post.update_counters [10, 15], :comment_count => 1
# # Executes the following SQL:
# # UPDATE posts
# # SET comment_count = comment_count + 1,
# # WHERE id IN (10, 15)
def update_counters(id, counters)
updates = counters.inject([]) { |list, (counter_name, increment)|
sign = increment < 0 ? "-" : "+"
list << "#{connection.quote_column_name(counter_name)} = COALESCE(#{connection.quote_column_name(counter_name)}, 0) #{sign} #{increment.abs}"
}.join(", ")
if id.is_a?(Array)
ids_list = id.map {|i| quote_value(i)}.join(', ')
condition = "IN (#{ids_list})"
else
condition = "= #{quote_value(id)}"
end
update_all(updates, "#{connection.quote_column_name(primary_key)} #{condition}")
end