### Home Classes Methods

### In Files

- lib/active_record/connection_adapters/postgresql_adapter.rb
- lib/active_record/connection_adapters/abstract/connection_specification.rb
- lib/active_record/connection_adapters/mysql_adapter.rb
- lib/active_record/connection_adapters/sqlite3_adapter.rb
- lib/active_record/connection_adapters/mysql2_adapter.rb
- lib/active_record/base.rb

### Parent

Object

### Methods

- ::===
- ::arel_engine
- ::arel_table
- ::clear_active_connections!
- ::configurations
- ::connected?
- ::connection
- ::connection_config
- ::connection_handler
- ::connection_id
- ::connection_id=
- ::connection_pool
- ::default_timezone
- ::establish_connection
- ::generated_feature_methods
- ::inspect
- ::logger
- ::mysql2_connection
- ::new
- ::remove_connection
- ::retrieve_connection
- ::schema_format
- ::timestamped_migrations
- #<=>
- #==
- #connection
- #encode_with
- #eql?
- #freeze
- #frozen?
- #hash
- #init_with
- #initialize_dup
- #inspect
- #readonly!
- #readonly?

### Included Modules

- ActiveRecord::Persistence
- ActiveRecord::ReadonlyAttributes
- ActiveRecord::ModelSchema
- ActiveRecord::Inheritance
- ActiveRecord::Scoping
- ActiveRecord::Sanitization
- ActiveRecord::AttributeAssignment
- ActiveModel::Conversion
- ActiveRecord::Integration
- ActiveRecord::Validations
- ActiveRecord::Locking::Optimistic
- ActiveRecord::Locking::Pessimistic
- ActiveRecord::AttributeMethods
- ActiveRecord::Callbacks
- ActiveModel::Observing
- ActiveRecord::Timestamp
- ActiveRecord::Associations
- ActiveRecord::IdentityMap
- ActiveModel::SecurePassword
- ActiveRecord::AutosaveAssociation
- ActiveRecord::NestedAttributes
- ActiveRecord::Aggregations
- ActiveRecord::Transactions
- ActiveRecord::Reflection
- ActiveRecord::Serialization
- ActiveRecord::Store

### Files

- README.rdoc

### Class/Module Index

Quicksearch

- ActiveRecord
- ActiveRecord::ActiveRecordError
- ActiveRecord::AdapterNotFound
- ActiveRecord::AdapterNotSpecified
- ActiveRecord::Aggregations
- ActiveRecord::Aggregations::ClassMethods
- ActiveRecord::AssociationTypeMismatch
- ActiveRecord::Associations
- ActiveRecord::Associations::ClassMethods
- ActiveRecord::AttributeAssignment
- ActiveRecord::AttributeAssignment::ClassMethods
- ActiveRecord::AttributeAssignmentError
- ActiveRecord::AttributeMethods
- ActiveRecord::AttributeMethods::BeforeTypeCast
- ActiveRecord::AttributeMethods::ClassMethods
- ActiveRecord::AttributeMethods::DeprecatedUnderscoreRead
- ActiveRecord::AttributeMethods::DeprecatedUnderscoreRead::ClassMethods
- ActiveRecord::AttributeMethods::Dirty
- ActiveRecord::AttributeMethods::PrimaryKey
- ActiveRecord::AttributeMethods::PrimaryKey::ClassMethods
- ActiveRecord::AttributeMethods::Query
- ActiveRecord::AttributeMethods::Read
- ActiveRecord::AttributeMethods::Read::ClassMethods
- ActiveRecord::AttributeMethods::Serialization
- ActiveRecord::AttributeMethods::Serialization::Attribute
- ActiveRecord::AttributeMethods::Serialization::ClassMethods
- ActiveRecord::AttributeMethods::TimeZoneConversion
- ActiveRecord::AttributeMethods::TimeZoneConversion::ClassMethods
- ActiveRecord::AttributeMethods::Write
- ActiveRecord::AttributeMethods::Write::ClassMethods
- ActiveRecord::AutosaveAssociation
- ActiveRecord::AutosaveAssociation::ClassMethods
- ActiveRecord::Base
- ActiveRecord::Batches
- ActiveRecord::Calculations
- ActiveRecord::Callbacks
- ActiveRecord::Coders
- ActiveRecord::ConfigurationError
- ActiveRecord::ConnectionAdapters
- ActiveRecord::ConnectionAdapters::AbstractAdapter
- ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter
- ActiveRecord::ConnectionAdapters::ConnectionHandler
- ActiveRecord::ConnectionAdapters::ConnectionManagement
- ActiveRecord::ConnectionAdapters::ConnectionPool
- ActiveRecord::ConnectionAdapters::DatabaseLimits
- ActiveRecord::ConnectionAdapters::DatabaseStatements
- ActiveRecord::ConnectionAdapters::Mysql2Adapter
- ActiveRecord::ConnectionAdapters::MysqlAdapter
- ActiveRecord::ConnectionAdapters::MysqlAdapter::StatementPool
- ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
- ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::StatementPool
- ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::TableDefinition
- ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::Utils
- ActiveRecord::ConnectionAdapters::PostgreSQLColumn
- ActiveRecord::ConnectionAdapters::QueryCache
- ActiveRecord::ConnectionAdapters::Quoting
- ActiveRecord::ConnectionAdapters::SQLiteAdapter
- ActiveRecord::ConnectionAdapters::SQLiteAdapter::ExplainPrettyPrinter
- ActiveRecord::ConnectionAdapters::SQLiteAdapter::StatementPool
- ActiveRecord::ConnectionAdapters::SQLiteAdapter::Version
- ActiveRecord::ConnectionAdapters::SchemaCache
- ActiveRecord::ConnectionAdapters::SchemaStatements
- ActiveRecord::ConnectionAdapters::StatementPool
- ActiveRecord::ConnectionAdapters::Table
- ActiveRecord::ConnectionAdapters::TableDefinition
- ActiveRecord::ConnectionNotEstablished
- ActiveRecord::ConnectionTimeoutError
- ActiveRecord::CounterCache
- ActiveRecord::DangerousAttributeError
- ActiveRecord::Delegation
- ActiveRecord::DynamicFinderMatch
- ActiveRecord::DynamicMatchers
- ActiveRecord::DynamicScopeMatch
- ActiveRecord::Explain
- ActiveRecord::FinderMethods
- ActiveRecord::Fixtures
- ActiveRecord::Fixtures::File
- ActiveRecord::Generators
- ActiveRecord::Generators::Migration
- ActiveRecord::Generators::MigrationGenerator
- ActiveRecord::Generators::ModelGenerator
- ActiveRecord::Generators::ObserverGenerator
- ActiveRecord::Generators::SessionMigrationGenerator
- ActiveRecord::IdentityMap
- ActiveRecord::IdentityMap::Middleware
- ActiveRecord::Inheritance
- ActiveRecord::Inheritance::ClassMethods
- ActiveRecord::Integration
- ActiveRecord::InvalidForeignKey
- ActiveRecord::IrreversibleMigration
- ActiveRecord::Locking
- ActiveRecord::Locking::Optimistic
- ActiveRecord::Locking::Optimistic::ClassMethods
- ActiveRecord::Locking::Pessimistic
- ActiveRecord::LogSubscriber
- ActiveRecord::Migration
- ActiveRecord::Migration::CommandRecorder
- ActiveRecord::MigrationProxy
- ActiveRecord::ModelSchema
- ActiveRecord::ModelSchema::ClassMethods
- ActiveRecord::MultiparameterAssignmentErrors
- ActiveRecord::NestedAttributes
- ActiveRecord::NestedAttributes::ClassMethods
- ActiveRecord::NestedAttributes::TooManyRecords
- ActiveRecord::Observer
- ActiveRecord::Persistence
- ActiveRecord::Persistence::ClassMethods
- ActiveRecord::PreparedStatementInvalid
- ActiveRecord::QueryCache
- ActiveRecord::QueryCache::ClassMethods
- ActiveRecord::QueryMethods
- ActiveRecord::Querying
- ActiveRecord::Railtie
- ActiveRecord::Railties
- ActiveRecord::Railties::ControllerRuntime
- ActiveRecord::Railties::ControllerRuntime::ClassMethods
- ActiveRecord::ReadOnlyRecord
- ActiveRecord::ReadonlyAttributes
- ActiveRecord::ReadonlyAttributes::ClassMethods
- ActiveRecord::RecordInvalid
- ActiveRecord::RecordNotFound
- ActiveRecord::RecordNotSaved
- ActiveRecord::RecordNotUnique
- ActiveRecord::Reflection
- ActiveRecord::Reflection::ClassMethods
- ActiveRecord::Reflection::MacroReflection
- ActiveRecord::Result
- ActiveRecord::Rollback
- ActiveRecord::Sanitization
- ActiveRecord::Sanitization::ClassMethods
- ActiveRecord::Schema
- ActiveRecord::Scoping
- ActiveRecord::Scoping::ClassMethods
- ActiveRecord::Scoping::Default
- ActiveRecord::Scoping::Default::ClassMethods
- ActiveRecord::Scoping::Named
- ActiveRecord::Scoping::Named::ClassMethods
- ActiveRecord::Serialization
- ActiveRecord::SerializationTypeMismatch
- ActiveRecord::SessionStore
- ActiveRecord::SessionStore::Session
- ActiveRecord::SessionStore::SqlBypass
- ActiveRecord::SpawnMethods
- ActiveRecord::StaleObjectError
- ActiveRecord::StatementInvalid
- ActiveRecord::Store
- ActiveRecord::Store::ClassMethods
- ActiveRecord::TestFixtures
- ActiveRecord::TestFixtures::ClassMethods
- ActiveRecord::ThrowResult
- ActiveRecord::Timestamp
- ActiveRecord::Transactions
- ActiveRecord::Transactions::ClassMethods
- ActiveRecord::Translation
- ActiveRecord::UnknownAttributeError
- ActiveRecord::UnknownPrimaryKey
- ActiveRecord::Validations
- ActiveRecord::Validations::AssociatedValidator
- ActiveRecord::Validations::ClassMethods
- ActiveRecord::Validations::UniquenessValidator
- ActiveRecord::WrappedDatabaseException
- Mysql
- Mysql::Result
- Mysql::Stmt
- Mysql::Time
- ArJdbcMySQL
- ArJdbcMySQL::Error

No matching classes.

# ActiveRecord::Base

# 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 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 `<attribute>_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 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 `find_by_`, `find_last_by_`, or `find_all_by_` and thus produces finders like `Person.find_by_user_name`, `Person.find_all_by_last_name`, and `Payment.find_by_transaction_id`. Instead of writing `Person.where(:user_name => user_name).first`, you just do `Person.find_by_user_name(user_name)`. And instead of writing `Person.where(:last_name => last_name).all`, you just do `Person.find_all_by_last_name(last_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.where(:user_name => user_name, :password => password).first
    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_all_by_amount(50)
    Payment.pending.find_last_by_amount(100)

The same dynamic finder style can be used to create the object if it doesn't already exist. This dynamic finder is called with `find_or_create_by_` 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.

    # 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 }

Adding an exclamation point (!) on to the end of `find_or_create_by_` will raise an `ActiveRecord::RecordInvalid` error if the new record is invalid.

Use the `find_or_initialize_by_` 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.

    # No 'Winter' tag exists
    winter = Tag.find_or_initialize_by_name("Winter")
    winter.persisted? # false

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.

    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.

Just like `find_by_*`, you can also use `scoped_by_*` to retrieve data. The good thing about using this feature is that the very first time result is returned using `method_missing` technique but after that the method is declared on the class. Henceforth `method_missing` will not be hit.

    User.scoped_by_user_name('David')

## 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: 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.

- SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.

- ConnectionNotEstablished+ - No connection has been established. Use `establish_connection` 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 `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.

- 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.

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.

### Public Class Methods

===(object) click to toggle source

Overwrite the default class equality method to provide support for association proxies.

    # File lib/active_record/base.rb, line 432
    def ===(object)
      object.is_a?(self)
    end

arel_engine() click to toggle source

    # File lib/active_record/base.rb, line 440
    def arel_engine
      @arel_engine ||= begin
        if self == ActiveRecord::Base
          ActiveRecord::Base
        else
          connection_handler.retrieve_connection_pool(self) ? self : superclass.arel_engine
        end
      end
    end

arel_table() click to toggle source

    # File lib/active_record/base.rb, line 436
    def arel_table
      @arel_table ||= Arel::Table.new(table_name, arel_engine)
    end

clear_active_connections!() click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 183
    def clear_active_connections!
      connection_handler.clear_active_connections!
    end

configurations click to toggle source

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'
       }
    }

    # File lib/active_record/base.rb, line 368
    cattr_accessor :configurations, :instance_writer => false

connected?() click to toggle source

Returns true if Active Record is connected.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 175
    def connected?
      connection_handler.connected?(self)
    end

connection() click to toggle source

Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work unrelated to any of the specific Active Records.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 144
    def connection
      retrieve_connection
    end

connection_config() click to toggle source

Returns the configuration of the associated connection as a hash:

    ActiveRecord::Base.connection_config
    # => {:pool=>5, :timeout=>5000, :database=>"db/development.sqlite3", :adapter=>"sqlite3"}

Please use only for reading.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 162
    def connection_config
      connection_pool.spec.config
    end

connection_handler click to toggle source

The connection handler

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 84
    class_attribute :connection_handler, :instance_writer => false

connection_id() click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 148
    def connection_id
      Thread.current['ActiveRecord::Base.connection_id']
    end

connection_id=(connection_id) click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 152
    def connection_id=(connection_id)
      Thread.current['ActiveRecord::Base.connection_id'] = connection_id
    end

connection_pool() click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 166
    def connection_pool
      connection_handler.retrieve_connection_pool(self) or raise ConnectionNotEstablished
    end

default_timezone click to toggle source

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.

    # File lib/active_record/base.rb, line 375
    cattr_accessor :default_timezone, :instance_writer => false

establish_connection(spec = ENV["DATABASE_URL"]) click to toggle source

Establishes the connection to the database. Accepts a hash as input where the `:adapter` key must be specified with the name of a database adapter (in lower-case) example for regular databases (MySQL, Postgresql, etc):

    ActiveRecord::Base.establish_connection(
      :adapter  => "mysql",
      :host     => "localhost",
      :username => "myuser",
      :password => "mypass",
      :database => "somedatabase"
    )

Example for SQLite database:

    ActiveRecord::Base.establish_connection(
      :adapter => "sqlite",
      :database  => "path/to/dbfile"
    )

Also accepts keys as strings (for parsing from YAML for example):

    ActiveRecord::Base.establish_connection(
      "adapter" => "sqlite",
      "database"  => "path/to/dbfile"
    )

Or a URL:

    ActiveRecord::Base.establish_connection(
      "postgres://myuser:mypass@localhost/somedatabase"
    )

The exceptions AdapterNotSpecified, AdapterNotFound and ArgumentError may be returned on an error.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 128
    def self.establish_connection(spec = ENV["DATABASE_URL"])
      resolver = ConnectionSpecification::Resolver.new spec, configurations
      spec = resolver.spec

      unless respond_to?(spec.adapter_method)
        raise AdapterNotFound, "database configuration specifies nonexistent #{spec.config[:adapter]} adapter"
      end

      remove_connection
      connection_handler.establish_connection name, spec
    end

generated_feature_methods() click to toggle source

    # File lib/active_record/base.rb, line 409
    def generated_feature_methods
      @generated_feature_methods ||= begin
        mod = const_set(:GeneratedFeatureMethods, Module.new)
        include mod
        mod
      end
    end

inspect() click to toggle source

Returns a string like 'Post(id:integer, title:string, body:text)'

    # File lib/active_record/base.rb, line 418
    def inspect
      if self == Base
        super
      elsif abstract_class?
        "#{super}(abstract)"
      elsif table_exists?
        attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', '
        "#{super}(#{attr_list})"
      else
        "#{super}(Table doesn't exist)"
      end
    end

logger click to toggle source

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`.

    # File lib/active_record/base.rb, line 339
    cattr_accessor :logger, :instance_writer => false

mysql2_connection(config) click to toggle source

Establishes a connection to the database that's used by all Active Record objects.

    # File lib/active_record/connection_adapters/mysql2_adapter.rb, line 9
    def self.mysql2_connection(config)
      config[:username] = 'root' if config[:username].nil?

      if Mysql2::Client.const_defined? :FOUND_ROWS
        config[:flags] = Mysql2::Client::FOUND_ROWS
      end

      client = Mysql2::Client.new(config.symbolize_keys)
      options = [config[:host], config[:username], config[:password], config[:database], config[:port], config[:socket], 0]
      ConnectionAdapters::Mysql2Adapter.new(client, logger, options, config)
    end

new(attributes = nil, options = {}) click to toggle source

New objects can be instantiated as either empty (pass no construction parameter) or pre-set with attributes but not yet saved (pass a hash with key names matching the associated table column names). In both instances, valid attribute keys are determined by the column names of the associated table -- hence you can't have attributes that aren't part of the table columns.

`initialize` respects mass-assignment security and accepts either `:as` or `:without_protection` options in the `options` parameter.

#### Examples

    # Instantiates a single new object
    User.new(:first_name => 'Jamie')

    # Instantiates a single new object using the :admin mass-assignment security role
    User.new({ :first_name => 'Jamie', :is_admin => true }, :as => :admin)

    # Instantiates a single new object bypassing mass-assignment security
    User.new({ :first_name => 'Jamie', :is_admin => true }, :without_protection => true)

    # File lib/active_record/base.rb, line 481
    def initialize(attributes = nil, options = {})
      defaults = Hash[self.class.column_defaults.map { |k, v| [k, v.duplicable? ? v.dup : v] }]
      @attributes = self.class.initialize_attributes(defaults)
      @association_cache = {}
      @aggregation_cache = {}
      @attributes_cache = {}
      @new_record = true
      @readonly = false
      @destroyed = false
      @marked_for_destruction = false
      @previously_changed = {}
      @changed_attributes = {}

      ensure_proper_type

      populate_with_current_scope_attributes

      assign_attributes(attributes, options) if attributes

      yield self if block_given?
      run_callbacks :initialize
    end

remove_connection(klass = self) click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 179
    def remove_connection(klass = self)
      connection_handler.remove_connection(klass)
    end

retrieve_connection() click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 170
    def retrieve_connection
      connection_handler.retrieve_connection(self)
    end

schema_format click to toggle source

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.

    # File lib/active_record/base.rb, line 386
    cattr_accessor :schema_format , :instance_writer => false

timestamped_migrations click to toggle source

Specify whether or not to use timestamps for migration versions

    # File lib/active_record/base.rb, line 392
    cattr_accessor :timestamped_migrations , :instance_writer => false

### Public Instance Methods

<=>(other_object) click to toggle source

Allows sort on objects

    # File lib/active_record/base.rb, line 618
    def <=>(other_object)
      if other_object.is_a?(self.class)
        self.to_key <=> other_object.to_key
      else
        nil
      end
    end

==(comparison_object) click to toggle source

Returns true if `comparison_object` is the same exact object, or `comparison_object` is of the same type and `self` has an ID and it is equal to `comparison_object.id`.

Note that new records are different from any other record by definition, unless the other record is the receiver itself. Besides, if you fetch existing records with `select` and leave the ID out, you're on your own, this predicate will return false.

Note also that destroying a record preserves its ID in the model instance, so deleted models are still comparable.

    # File lib/active_record/base.rb, line 593
    def ==(comparison_object)
      super ||
        comparison_object.instance_of?(self.class) &&
        id.present? &&
        comparison_object.id == id
    end

Also aliased as: eql?
connection() click to toggle source

Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work that isn't easily done without going straight to SQL.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 90
    def connection
      self.class.connection
    end

encode_with(coder) click to toggle source

Populate `coder` with attributes about this record that should be serialized. The structure of `coder` defined in this method is guaranteed to match the structure of `coder` passed to the `init_with` method.

Example:

    class Post < ActiveRecord::Base
    end
    coder = {}
    Post.new.encode_with(coder)
    coder # => { 'id' => nil, ... }

    # File lib/active_record/base.rb, line 580
    def encode_with(coder)
      coder['attributes'] = attributes
    end

eql?(comparison_object) click to toggle source
Alias for: ==
freeze() click to toggle source

Freeze the attributes hash such that associations are still accessible, even on destroyed records.

    # File lib/active_record/base.rb, line 608
    def freeze
      @attributes.freeze; self
    end

frozen?() click to toggle source

Returns `true` if the attributes hash has been frozen.

    # File lib/active_record/base.rb, line 613
    def frozen?
      @attributes.frozen?
    end

hash() click to toggle source

Delegates to id in order to allow two records of the same type and id to work with something like:

    [ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]

    # File lib/active_record/base.rb, line 603
    def hash
      id.hash
    end

init_with(coder) click to toggle source

Initialize an empty model object from `coder`. `coder` must contain the attributes necessary for initializing an empty model object. For example:

    class Post < ActiveRecord::Base
    end

    post = Post.allocate
    post.init_with('attributes' => { 'title' => 'hello world' })
    post.title # => 'hello world'

    # File lib/active_record/base.rb, line 514
    def init_with(coder)
      @attributes = self.class.initialize_attributes(coder['attributes'])
      @relation = nil

      @attributes_cache, @previously_changed, @changed_attributes = {}, {}, {}
      @association_cache = {}
      @aggregation_cache = {}
      @readonly = @destroyed = @marked_for_destruction = false
      @new_record = false
      run_callbacks :find
      run_callbacks :initialize

      self
    end

initialize_dup(other) click to toggle source

Duped objects have no id assigned and are treated as new records. Note that this is a "shallow" copy as it copies the object's attributes only, not its associations. The extent of a "deep" copy is application specific and is therefore left to the application to implement according to its need. The dup method does not preserve the timestamps (created|updated)_(at|on).

    # File lib/active_record/base.rb, line 535
    def initialize_dup(other)
      cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
      self.class.initialize_attributes(cloned_attributes, :serialized => false)

      cloned_attributes.delete(self.class.primary_key)

      @attributes = cloned_attributes

      _run_after_initialize_callbacks if respond_to?(:_run_after_initialize_callbacks)

      @changed_attributes = {}
      self.class.column_defaults.each do |attr, orig_value|
        @changed_attributes[attr] = orig_value if _field_changed?(attr, orig_value, @attributes[attr])
      end

      @aggregation_cache = {}
      @association_cache = {}
      @attributes_cache = {}
      @new_record  = true

      ensure_proper_type
      super
    end

inspect() click to toggle source

Returns the contents of the record as a nicely formatted string.

    # File lib/active_record/base.rb, line 638
    def inspect
      inspection = if @attributes
                     self.class.column_names.collect { |name|
                       if has_attribute?(name)
                         "#{name}: #{attribute_for_inspect(name)}"
                       end
                     }.compact.join(", ")
                   else
                     "not initialized"
                   end
      "#<#{self.class} #{inspection}>"
    end

readonly!() click to toggle source

Marks this record as read only.

    # File lib/active_record/base.rb, line 633
    def readonly!
      @readonly = true
    end

readonly?() click to toggle source

Returns `true` if the record is read only. Records loaded through joins with piggy-back attributes will be marked as read only since they cannot be saved.

    # File lib/active_record/base.rb, line 628
    def readonly?
      @readonly
    end

[Validate]

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