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

Returns whether this class is a base AR class. If A is a base class and B descends from A, then B.base_class will return B.

This is an alias for find(:all). You can pass in all the same arguments to this method as you can to find(:all)

Deprecated and no longer has any effect.

Deprecated and no longer has any effect.

Specifies a white list of model attributes that can be set via mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes)

This is the opposite of the attr_protected macro: Mass-assignment will only set attributes in this list, to assign to the rest of attributes you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms. If you‘d rather start from an all-open default and restrict attributes as needed, have a look at attr_protected.

  class Customer < ActiveRecord::Base
    attr_accessible :name, :nickname
  end

  customer = Customer.new(:name => "David", :nickname => "Dave", :credit_rating => "Excellent")
  customer.credit_rating # => nil
  customer.attributes = { :name => "Jolly fellow", :credit_rating => "Superb" }
  customer.credit_rating # => nil

  customer.credit_rating = "Average"
  customer.credit_rating # => "Average"

Attributes named in this macro are protected from mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes).

Mass-assignment to these attributes will simply be ignored, to assign to them you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms.

  class Customer < ActiveRecord::Base
    attr_protected :credit_rating
  end

  customer = Customer.new("name" => David, "credit_rating" => "Excellent")
  customer.credit_rating # => nil
  customer.attributes = { "description" => "Jolly fellow", "credit_rating" => "Superb" }
  customer.credit_rating # => nil

  customer.credit_rating = "Average"
  customer.credit_rating # => "Average"

To start from an all-closed default and enable attributes as needed, have a look at attr_accessible.

Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.

Returns the base AR subclass that this class descends from. If A extends AR::Base, A.base_class will return A. If B descends from A through some arbitrarily deep hierarchy, B.base_class will return A.

Log and benchmark multiple statements in a single block. Example:

  Project.benchmark("Creating project") do
    project = Project.create("name" => "stuff")
    project.create_manager("name" => "David")
    project.milestones << Milestone.find(:all)
  end

The benchmark is only recorded if the current level of the logger is less than or equal to the log_level, which makes it easy to include benchmarking statements in production software that will remain inexpensive because the benchmark will only be conducted if the log level is low enough.

The logging of the multiple statements is turned off unless use_silence is set to false.

Returns an array of column names as strings.

Returns an array of column objects for the table associated with this class.

Returns a hash of column objects for the table associated with this class.

Returns true if ActiveRecord is connected.

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.

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

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"

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

Decrement a number field by one, usually representing a count.

This works the same as increment_counter but reduces the column value by 1 instead of increasing it.

Parameters

• counter_name - The name of the field that should be decremented.
• id - The id of the object that should be decremented.

Examples

  # Decrement the post_count column for the record with an id of 5
  DiscussionBoard.decrement_counter(:post_count, 5)

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 :dependent association options or Observer methods.

You can delete multiple rows at once by passing an Array of ids.

Note: Although it is often much faster than the alternative, destroy, 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])

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 :dependent 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 before_* or after_destroy callbacks, use the destroy_all method instead.

True if this isn‘t a concrete subclass needing a STI type condition.

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)

Destroys the records matching conditions by instantiating each record and calling its destroy method. Each object‘s callbacks are executed (including :dependent 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")

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"
  )

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

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 ‘5‘).
• Array - Finds the record that matches these find-style conditions (such as [‘color = ?’, ‘red’]).
• Hash - Finds the record that matches these find-style conditions (such as {:color => ‘red’}).
• 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 name = ‘Jamie‘), since it would be sanitized and then queried against the primary key column, like id = ‘name = \’Jamie\’‘.

Examples

  Person.exists?(5)
  Person.exists?('5')
  Person.exists?(:name => "David")
  Person.exists?(['name LIKE ?', "%#{query}%"])
  Person.exists?

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 Model.find(:first, *args) or its shortcut Model.first(*args).
• 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 Model.find(:last, *args) or its shortcut Model.last(*args).
• Find all - This will return all the records matched by the options used. If no records are found, an empty array is returned. Use Model.find(:all, *args) or its shortcut Model.all(*args).

All approaches accept an options hash as their last parameter.

Parameters

• :conditions - An SQL fragment like "administrator = 1", [ "user_name = ?", username ], or ["user_name = :user_name", { :user_name => user_name }]. See conditions in the intro.
• :order - An SQL fragment like "created_at DESC, name".
• :group - An attribute name by which the result should be grouped. Uses the GROUP BY SQL-clause.
• :having - Combined with +:group+ this can be used to filter the records that a GROUP BY returns. Uses the HAVING SQL-clause.
• :limit - An integer determining the limit on the number of rows that should be returned.
• :offset - An integer determining the offset from where the rows should be fetched. So at 5, it would skip rows 0 through 4.
• :joins - 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 :include option, which will perform an INNER JOIN 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 :readonly => false to override.
• :include - Names associations that should be loaded alongside. The symbols named refer to already defined associations. See eager loading under Associations.
• :select - 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").
• :from - 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).
• :readonly - Mark the returned records read-only so they cannot be saved or updated.
• :lock - An SQL fragment like "FOR UPDATE" or "LOCK IN SHARE MODE". :lock => true 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 :order 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 person.visits == 2, add 1 to it, and save, resulting in two saves of person.visits = 3. By locking the row, the second transaction has to wait until the first is finished; we get the expected person.visits == 4.

  Person.transaction do
    person = Person.find(1, :lock => true)
    person.visits += 1
    person.save!
  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 Product.find_by_sql 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"}>, ...]

A convenience wrapper for find(:first, *args). You can pass in all the same arguments to this method as you can to find(:first).

Transforms attribute key names into a more humane format, such as "First name" instead of "first_name". Example:

  Person.human_attribute_name("first_name") # => "First name"

This used to be depricated in favor of humanize, but is now preferred, because it automatically uses the I18n module now. Specify options with additional translating options.

Transform the modelname into a more humane format, using I18n. Defaults to the basic humanize method. Default scope of the translation is activerecord.models Specify options with additional translating options.

Increment a number field by one, usually representing a count.

This is used for caching aggregate values, so that they don‘t need to be computed every time. For example, a DiscussionBoard may cache post_count and comment_count otherwise every time the board is shown it would have to run an SQL query to find how many posts and comments there are.

Parameters

• counter_name - The name of the field that should be incremented.
• id - The id of the object that should be incremented.

Examples

  # Increment the post_count column for the record with an id of 5
  DiscussionBoard.increment_counter(:post_count, 5)

Defines the column name for use with single table inheritance — can be set in subclasses like so: self.inheritance_column = "type_id"

Returns a string like ‘Post id:integer, title:string, body:text‘

A convenience wrapper for find(:last, *args). You can pass in all the same arguments to this method as you can to find(:last).

Merges conditions so that the result is a valid condition

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.

Defines the primary key field — can be overridden in subclasses. Overwriting will negate any effect of the primary_key_prefix_type setting, though.

Returns an array of all the attributes that have been specified as readonly.

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

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

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

       t.timestamps
     end

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

   def self.down
     drop_table :job_levels
   end
 end

If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object, then specify the name of that attribute using this method and it will be handled automatically. The serialization is done through YAML. If class_name is specified, the serialized object must be of that class on retrieval or SerializationTypeMismatch will be raised.

Parameters

• attr_name - The field name that should be serialized.
• class_name - Optional, class name that the object type should be equal to.

Example

  # Serialize a preferences attribute
  class User
    serialize :preferences
  end

Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.

Sets the name of the inheritance column to use to the given value, or (if the value # is nil or false) to the value returned by the given block.

  class Project < ActiveRecord::Base
    set_inheritance_column do
      original_inheritance_column + "_id"
    end
  end

Sets the name of the primary key column to use to the given value, or (if the value is nil or false) to the value returned by the given block.

  class Project < ActiveRecord::Base
    set_primary_key "sysid"
  end

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

If a sequence name is not explicitly set when using Oracle or Firebird, it will default to the commonly used pattern of: #{table_name}_seq

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

  class Project < ActiveRecord::Base
    set_sequence_name "projectseq"   # default would have been "project_seq"
  end

Sets the table name to use to the given value, or (if the value is nil or false) to the value returned by the given block.

  class Project < ActiveRecord::Base
    set_table_name "project"
  end

Silences the logger for the duration of the block.

Indicates whether the table associated with this class exists

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

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

Examples

  class Invoice < ActiveRecord::Base; end;
  file                  class               table_name
  invoice.rb            Invoice             invoices

  class Invoice < ActiveRecord::Base; class Lineitem < ActiveRecord::Base; end; end;
  file                  class               table_name
  invoice.rb            Invoice::Lineitem   invoice_lineitems

  module Invoice; class Lineitem < ActiveRecord::Base; end; end;
  file                  class               table_name
  invoice/lineitem.rb   Invoice::Lineitem   lineitems

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

You can also overwrite this class method to allow for unguessable links, such as a Mouse class with a link to a "mice" table. Example:

  class Mouse < ActiveRecord::Base
    set_table_name "mice"
  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)

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.

Parameters

• updates - A string of column and value pairs that will be set on any records that match conditions. This creates the SET clause of the generated SQL.
• conditions - An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. See conditions in the intro for more info.
• options - Additional options are :limit and :order, see the examples for usage.

Examples

  # Update all billing objects with the 3 different attributes given
  Billing.update_all( "category = 'authorized', approved = 1, author = 'David'" )

  # Update records that match our conditions
  Billing.update_all( "author = 'David'", "title LIKE '%Rails%'" )

  # Update records that match our conditions but limit it to 5 ordered by date
  Billing.update_all( "author = 'David'", "title LIKE '%Rails%'",
                        :order => 'created_at', :limit => 5 )

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)

Deprecated and no longer has any effect.

Deprecated and no longer has any effect.

Returns the class descending directly from ActiveRecord::Base or an abstract class, if any, in the inheritance hierarchy.

Returns the class type of the record using the current module as a prefix. So descendants of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.

Sets the default options for the model. The format of the options argument is the same as in find.

  class Person < ActiveRecord::Base
    default_scope :order => 'last_name, first_name'
  end

Accepts a hash of SQL conditions and replaces those attributes that correspond to a composed_of relationship with their expanded aggregate attribute values. Given:

    class Person < ActiveRecord::Base
      composed_of :address, :class_name => "Address",
        :mapping => [%w(address_street street), %w(address_city city)]
    end

Then:

    { :address => Address.new("813 abc st.", "chicago") }
      # => { :address_street => "813 abc st.", :address_city => "chicago" }

Accepts an array of conditions. The array has each value sanitized and interpolated into the SQL statement.

  ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a SET clause.

  { :name => nil, :group_id => 4 }  returns "name = NULL , group_id='4'"

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a WHERE clause.

  ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
  { :name => "foo'bar", :group_id => 4 }  returns "name='foo''bar' and group_id='4'"
  "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"

Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.

  { :status => nil, :group_id => 1 }
    # => "status = NULL , group_id = 1"

Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.

  { :name => "foo'bar", :group_id => 4 }
    # => "name='foo''bar' and group_id= 4"
  { :status => nil, :group_id => [1,2,3] }
    # => "status IS NULL and group_id IN (1,2,3)"
  { :age => 13..18 }
    # => "age BETWEEN 13 AND 18"
  { 'other_records.id' => 7 }
    # => "`other_records`.`id` = 7"
  { :other_records => { :id => 7 } }
    # => "`other_records`.`id` = 7"

And for value objects on a composed_of relationship:

  { :address => Address.new("123 abc st.", "chicago") }
    # => "address_street='123 abc st.' and address_city='chicago'"

Works like with_scope, but discards any nested properties.

Scope parameters to method calls within the block. Takes a hash of method_name => parameters hash. method_name may be :find or :create. :find parameters may include the :conditions, :joins, :include, :offset, :limit, and :readonly options. :create parameters are an attributes hash.

  class Article < ActiveRecord::Base
    def self.create_with_scope
      with_scope(:find => { :conditions => "blog_id = 1" }, :create => { :blog_id => 1 }) do
        find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
        a = create(1)
        a.blog_id # => 1
      end
    end
  end

In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of :conditions, :include, and :joins options in :find, which are merged.

:joins options are uniqued so multiple scopes can join in the same table without table aliasing problems. If you need to join multiple tables, but still want one of the tables to be uniqued, use the array of strings format for your joins.

  class Article < ActiveRecord::Base
    def self.find_with_scope
      with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }, :create => { :blog_id => 1 }) do
        with_scope(:find => { :limit => 10 })
          find(:all) # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
        end
        with_scope(:find => { :conditions => "author_id = 3" })
          find(:all) # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1
        end
      end
    end
  end

You can ignore any previous scopings by using the with_exclusive_scope method.

  class Article < ActiveRecord::Base
    def self.find_with_exclusive_scope
      with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }) do
        with_exclusive_scope(:find => { :limit => 10 })
          find(:all) # => SELECT * from articles LIMIT 10
        end
      end
    end
  end

Note: the +:find+ scope also has effect on update and deletion methods, like update_all and delete_all.

Returns true if the comparison_object is the same object, or is of the same type and has the same id.

Returns the value of the attribute identified by attr_name after it has been typecast (for example, "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)). (Alias for the protected read_attribute method).

Updates the attribute identified by attr_name with the specified value. (Alias for the protected write_attribute method).

Returns an inspect-like string for the value of the attribute attr_name. String attributes are elided after 50 characters, and Date and Time attributes are returned in the :db format. Other attributes return the value of inspect without modification.

  person = Person.create!(:name => "David Heinemeier Hansson " * 3)

  person.attribute_for_inspect(:name)
  # => '"David Heinemeier Hansson David Heinemeier Hansson D..."'

  person.attribute_for_inspect(:created_at)
  # => '"2009-01-12 04:48:57"'

Returns an array of names for the attributes available on this object sorted alphabetically.

Returns true if the specified attribute has been set by the user or by a database load and is neither nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings).

Returns a hash of all the attributes with their names as keys and the values of the attributes as values.

Allows you to set all the attributes at once by passing in a hash with keys matching the attribute names (which again matches the column names).

If guard_protected_attributes is true (the default), then sensitive attributes can be protected from this form of mass-assignment by using the attr_protected macro. Or you can alternatively specify which attributes can be accessed with the attr_accessible macro. Then all the attributes not included in that won‘t be allowed to be mass-assigned.

  class User < ActiveRecord::Base
    attr_protected :is_admin
  end

  user = User.new
  user.attributes = { :username => 'Phusion', :is_admin => true }
  user.username   # => "Phusion"
  user.is_admin?  # => false

  user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false)
  user.is_admin?  # => true

Returns a hash of attributes before typecasting and deserialization.

Returns an instance of the specified klass with the attributes of the current record. This is mostly useful in relation to single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record identification in Action Pack to allow, say, Client < Company to do something like render :partial => @client.becomes(Company) to render that instance using the companies/company partial instead of clients/client.

Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either instance will affect the other.

Returns a cache key that can be used to identify this record.

Examples

  Product.new.cache_key     # => "products/new"
  Product.find(5).cache_key # => "products/5" (updated_at not available)
  Person.find(5).cache_key  # => "people/5-20071224150000" (updated_at available)

Returns a clone of the record that hasn‘t been assigned an id yet and is treated as a new record. Note that this is a "shallow" clone: it copies the object‘s attributes only, not its associations. The extent of a "deep" clone is application-specific and is therefore left to the application to implement according to its need.

Returns the column object for the named attribute.

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.

Initializes attribute to zero if nil and subtracts the value passed as by (default is 1). The decrement is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.

Wrapper around decrement that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can‘t be persisted). Returns the frozen instance.

The row is simply removed with a SQL DELETE statement on the record‘s primary key, and no callbacks are executed.

To enforce the object‘s before_destroy and after_destroy callbacks, Observer methods, or any :dependent association options, use destroy.

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can‘t be persisted).

Delegates to ==

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

Returns true if the attributes hash has been frozen.

Returns true if the given attribute is in the attributes hash

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) ]

A model instance‘s primary key is always available as model.id whether you name it the default ‘id’ or set it to something else.

Sets the primary ID.

Initializes attribute to zero if nil and adds the value passed as by (default is 1). The increment is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.

Wrapper around increment that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.

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

Returns true if this object hasn‘t been saved yet — that is, a record for the object doesn‘t exist yet; otherwise, returns false.

Marks this record as read only.

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.

Reloads the attributes of this object from the database. The optional options argument is passed to find when reloading so you may do e.g. record.reload(:lock => true) to reload the same record with an exclusive row lock.

Saves the model.

If the model is new a record gets created in the database, otherwise the existing record gets updated.

If perform_validation is true validations run. If any of them fail the action is cancelled and save returns false. If the flag is false validations are bypassed altogether. See ActiveRecord::Validations for more information.

There‘s a series of callbacks associated with save. If any of the before_* callbacks return false the action is cancelled and save returns false. See ActiveRecord::Callbacks for further details.

Saves the model.

If the model is new a record gets created in the database, otherwise the existing record gets updated.

With save! validations always run. If any of them fail ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations for more information.

There‘s a series of callbacks associated with save!. If any of the before_* callbacks return false the action is cancelled and save! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.

Returns a String, which Action Pack uses for constructing an URL to this object. The default implementation returns this record‘s id as a String, or nil if this record‘s unsaved.

For example, suppose that you have a User model, and that you have a map.resources :users route. Normally, user_path will construct a path with the user object‘s ‘id’ in it:

  user = User.find_by_name('Phusion')
  user_path(user)  # => "/users/1"

You can override to_param in your model to make user_path construct a path using the user‘s name instead of the user‘s id:

  class User < ActiveRecord::Base
    def to_param  # overridden
      name
    end
  end

  user = User.find_by_name('Phusion')
  user_path(user)  # => "/users/Phusion"

Assigns to attribute the boolean opposite of attribute?. So if the predicate returns true the attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.

Wrapper around toggle that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.

Updates a single attribute and saves the record without going through the normal validation procedure. This is especially useful for boolean flags on existing records. The regular update_attribute method in Base is replaced with this when the validations module is mixed in, which it is by default.

Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will fail and false will be returned.

Updates an object just like Base.update_attributes but calls save! instead of save so an exception is raised if the record is invalid.