module ActiveRecord::QueryMethods

Constants

FROZEN_EMPTY_ARRAY
FROZEN_EMPTY_HASH
VALID_UNSCOPING_VALUES

Public Instance Methods

and(other) click to toggle source

Returns a new relation, which is the logical intersection of this relation and the one passed as an argument.

The two relations must be structurally compatible: they must be scoping the same model, and they must differ only by where (if no group has been defined) or having (if a group is present).

Post.where(id: [1, 2]).and(Post.where(id: [2, 3]))
# SELECT `posts`.* FROM `posts` WHERE `posts`.`id` IN (1, 2) AND `posts`.`id` IN (2, 3)
# File lib/active_record/relation/query_methods.rb, line 681
def and(other)
  if other.is_a?(Relation)
    spawn.and!(other)
  else
    raise ArgumentError, "You have passed #{other.class.name} object to #and. Pass an ActiveRecord::Relation object instead."
  end
end
annotate(*args) click to toggle source

Adds an SQL comment to queries generated from this relation. For example:

User.annotate("selecting user names").select(:name)
# SELECT "users"."name" FROM "users" /* selecting user names */

User.annotate("selecting", "user", "names").select(:name)
# SELECT "users"."name" FROM "users" /* selecting */ /* user */ /* names */

The SQL block comment delimiters, “/*” and “*/”, will be added automatically.

Some escaping is performed, however untrusted user input should not be used.

# File lib/active_record/relation/query_methods.rb, line 1040
def annotate(*args)
  check_if_method_has_arguments!(:annotate, args)
  spawn.annotate!(*args)
end
create_with(value) click to toggle source

Sets attributes to be used when creating new records from a relation object.

users = User.where(name: 'Oscar')
users.new.name # => 'Oscar'

users = users.create_with(name: 'DHH')
users.new.name # => 'DHH'

You can pass nil to create_with to reset attributes:

users = users.create_with(nil)
users.new.name # => 'Oscar'
# File lib/active_record/relation/query_methods.rb, line 874
def create_with(value)
  spawn.create_with!(value)
end
distinct(value = true) click to toggle source

Specifies whether the records should be unique or not. For example:

User.select(:name)
# Might return two records with the same name

User.select(:name).distinct
# Returns 1 record per distinct name

User.select(:name).distinct.distinct(false)
# You can also remove the uniqueness
# File lib/active_record/relation/query_methods.rb, line 921
def distinct(value = true)
  spawn.distinct!(value)
end
eager_load(*args) click to toggle source

Forces eager loading by performing a LEFT OUTER JOIN on args:

User.eager_load(:posts)
# SELECT "users"."id" AS t0_r0, "users"."name" AS t0_r1, ...
# FROM "users" LEFT OUTER JOIN "posts" ON "posts"."user_id" =
# "users"."id"
# File lib/active_record/relation/query_methods.rb, line 166
def eager_load(*args)
  check_if_method_has_arguments!(:eager_load, args)
  spawn.eager_load!(*args)
end
extending(*modules, &block) click to toggle source

Used to extend a scope with additional methods, either through a module or through a block provided.

The object returned is a relation, which can be further extended.

Using a module

module Pagination
  def page(number)
    # pagination code goes here
  end
end

scope = Model.all.extending(Pagination)
scope.page(params[:page])

You can also pass a list of modules:

scope = Model.all.extending(Pagination, SomethingElse)

Using a block

scope = Model.all.extending do
  def page(number)
    # pagination code goes here
  end
end
scope.page(params[:page])

You can also use a block and a module list:

scope = Model.all.extending(Pagination) do
  def per_page(number)
    # pagination code goes here
  end
end
# File lib/active_record/relation/query_methods.rb, line 967
def extending(*modules, &block)
  if modules.any? || block
    spawn.extending!(*modules, &block)
  else
    self
  end
end
extract_associated(association) click to toggle source

Extracts a named association from the relation. The named association is first preloaded, then the individual association records are collected from the relation. Like so:

account.memberships.extract_associated(:user)
# => Returns collection of User records

This is short-hand for:

account.memberships.preload(:user).collect(&:user)
# File lib/active_record/relation/query_methods.rb, line 199
def extract_associated(association)
  preload(association).collect(&association)
end
from(value, subquery_name = nil) click to toggle source

Specifies table from which the records will be fetched. For example:

Topic.select('title').from('posts')
# SELECT title FROM posts

Can accept other relation objects. For example:

Topic.select('title').from(Topic.approved)
# SELECT title FROM (SELECT * FROM topics WHERE approved = 't') subquery

Topic.select('a.title').from(Topic.approved, :a)
# SELECT a.title FROM (SELECT * FROM topics WHERE approved = 't') a
# File lib/active_record/relation/query_methods.rb, line 902
def from(value, subquery_name = nil)
  spawn.from!(value, subquery_name)
end
group(*args) click to toggle source

Allows to specify a group attribute:

User.group(:name)
# SELECT "users".* FROM "users" GROUP BY name

Returns an array with distinct records based on the group attribute:

User.select([:id, :name])
# => [#<User id: 1, name: "Oscar">, #<User id: 2, name: "Oscar">, #<User id: 3, name: "Foo">]

User.group(:name)
# => [#<User id: 3, name: "Foo", ...>, #<User id: 2, name: "Oscar", ...>]

User.group('name AS grouped_name, age')
# => [#<User id: 3, name: "Foo", age: 21, ...>, #<User id: 2, name: "Oscar", age: 21, ...>, #<User id: 5, name: "Foo", age: 23, ...>]

Passing in an array of attributes to group by is also supported.

User.select([:id, :first_name]).group(:id, :first_name).first(3)
# => [#<User id: 1, first_name: "Bill">, #<User id: 2, first_name: "Earl">, #<User id: 3, first_name: "Beto">]
# File lib/active_record/relation/query_methods.rb, line 322
def group(*args)
  check_if_method_has_arguments!(:group, args)
  spawn.group!(*args)
end
having(opts, *rest) click to toggle source

Allows to specify a HAVING clause. Note that you can't use HAVING without also specifying a GROUP clause.

Order.having('SUM(price) > 30').group('user_id')
# File lib/active_record/relation/query_methods.rb, line 739
def having(opts, *rest)
  opts.blank? ? self : spawn.having!(opts, *rest)
end
includes(*args) click to toggle source

Specify relationships to be included in the result set. For example:

users = User.includes(:address)
users.each do |user|
  user.address.city
end

allows you to access the address attribute of the User model without firing an additional query. This will often result in a performance improvement over a simple join.

You can also specify multiple relationships, like this:

users = User.includes(:address, :friends)

Loading nested relationships is possible using a Hash:

users = User.includes(:address, friends: [:address, :followers])

conditions

If you want to add string conditions to your included models, you'll have to explicitly reference them. For example:

User.includes(:posts).where('posts.name = ?', 'example')

Will throw an error, but this will work:

User.includes(:posts).where('posts.name = ?', 'example').references(:posts)

Note that includes works with association names while references needs the actual table name.

If you pass the conditions via hash, you don't need to call references explicitly, as where references the tables for you. For example, this will work correctly:

User.includes(:posts).where(posts: { name: 'example' })
# File lib/active_record/relation/query_methods.rb, line 150
def includes(*args)
  check_if_method_has_arguments!(:includes, args)
  spawn.includes!(*args)
end
joins(*args) click to toggle source

Performs a joins on args. The given symbol(s) should match the name of the association(s).

User.joins(:posts)
# SELECT "users".*
# FROM "users"
# INNER JOIN "posts" ON "posts"."user_id" = "users"."id"

Multiple joins:

User.joins(:posts, :account)
# SELECT "users".*
# FROM "users"
# INNER JOIN "posts" ON "posts"."user_id" = "users"."id"
# INNER JOIN "accounts" ON "accounts"."id" = "users"."account_id"

Nested joins:

User.joins(posts: [:comments])
# SELECT "users".*
# FROM "users"
# INNER JOIN "posts" ON "posts"."user_id" = "users"."id"
# INNER JOIN "comments" ON "comments"."post_id" = "posts"."id"

You can use strings in order to customize your joins:

User.joins("LEFT JOIN bookmarks ON bookmarks.bookmarkable_type = 'Post' AND bookmarks.user_id = users.id")
# SELECT "users".* FROM "users" LEFT JOIN bookmarks ON bookmarks.bookmarkable_type = 'Post' AND bookmarks.user_id = users.id
# File lib/active_record/relation/query_methods.rb, line 489
def joins(*args)
  check_if_method_has_arguments!(:joins, args)
  spawn.joins!(*args)
end
left_joins(*args)
Alias for: left_outer_joins
left_outer_joins(*args) click to toggle source

Performs a left outer joins on args:

User.left_outer_joins(:posts)
=> SELECT "users".* FROM "users" LEFT OUTER JOIN "posts" ON "posts"."user_id" = "users"."id"
# File lib/active_record/relation/query_methods.rb, line 504
def left_outer_joins(*args)
  check_if_method_has_arguments!(__callee__, args)
  spawn.left_outer_joins!(*args)
end
Also aliased as: left_joins
limit(value) click to toggle source

Specifies a limit for the number of records to retrieve.

User.limit(10) # generated SQL has 'LIMIT 10'

User.limit(10).limit(20) # generated SQL has 'LIMIT 20'
# File lib/active_record/relation/query_methods.rb, line 753
def limit(value)
  spawn.limit!(value)
end
lock(locks = true) click to toggle source

Specifies locking settings (default to true). For more information on locking, please see ActiveRecord::Locking.

# File lib/active_record/relation/query_methods.rb, line 780
def lock(locks = true)
  spawn.lock!(locks)
end
none() click to toggle source

Returns a chainable relation with zero records.

The returned relation implements the Null Object pattern. It is an object with defined null behavior and always returns an empty array of records without querying the database.

Any subsequent condition chained to the returned relation will continue generating an empty relation and will not fire any query to the database.

Used in cases where a method or scope could return zero records but the result needs to be chainable.

For example:

@posts = current_user.visible_posts.where(name: params[:name])
# the visible_posts method is expected to return a chainable Relation

def visible_posts
  case role
  when 'Country Manager'
    Post.where(country: country)
  when 'Reviewer'
    Post.published
  when 'Bad User'
    Post.none # It can't be chained if [] is returned.
  end
end
# File lib/active_record/relation/query_methods.rb, line 823
def none
  spawn.none!
end
offset(value) click to toggle source

Specifies the number of rows to skip before returning rows.

User.offset(10) # generated SQL has "OFFSET 10"

Should be used with order.

User.offset(10).order("name ASC")
# File lib/active_record/relation/query_methods.rb, line 769
def offset(value)
  spawn.offset!(value)
end
optimizer_hints(*args) click to toggle source

Specify optimizer hints to be used in the SELECT statement.

Example (for MySQL):

Topic.optimizer_hints("MAX_EXECUTION_TIME(50000)", "NO_INDEX_MERGE(topics)")
# SELECT /*+ MAX_EXECUTION_TIME(50000) NO_INDEX_MERGE(topics) */ `topics`.* FROM `topics`

Example (for PostgreSQL with pg_hint_plan):

Topic.optimizer_hints("SeqScan(topics)", "Parallel(topics 8)")
# SELECT /*+ SeqScan(topics) Parallel(topics 8) */ "topics".* FROM "topics"
# File lib/active_record/relation/query_methods.rb, line 996
def optimizer_hints(*args)
  check_if_method_has_arguments!(:optimizer_hints, args)
  spawn.optimizer_hints!(*args)
end
or(other) click to toggle source

Returns a new relation, which is the logical union of this relation and the one passed as an argument.

The two relations must be structurally compatible: they must be scoping the same model, and they must differ only by where (if no group has been defined) or having (if a group is present).

Post.where("id = 1").or(Post.where("author_id = 3"))
# SELECT `posts`.* FROM `posts` WHERE ((id = 1) OR (author_id = 3))
# File lib/active_record/relation/query_methods.rb, line 713
def or(other)
  if other.is_a?(Relation)
    spawn.or!(other)
  else
    raise ArgumentError, "You have passed #{other.class.name} object to #or. Pass an ActiveRecord::Relation object instead."
  end
end
order(*args) click to toggle source

Allows to specify an order attribute:

User.order(:name)
# SELECT "users".* FROM "users" ORDER BY "users"."name" ASC

User.order(email: :desc)
# SELECT "users".* FROM "users" ORDER BY "users"."email" DESC

User.order(:name, email: :desc)
# SELECT "users".* FROM "users" ORDER BY "users"."name" ASC, "users"."email" DESC

User.order('name')
# SELECT "users".* FROM "users" ORDER BY name

User.order('name DESC')
# SELECT "users".* FROM "users" ORDER BY name DESC

User.order('name DESC, email')
# SELECT "users".* FROM "users" ORDER BY name DESC, email
# File lib/active_record/relation/query_methods.rb, line 351
def order(*args)
  check_if_method_has_arguments!(:order, args) do
    sanitize_order_arguments(args)
  end
  spawn.order!(*args)
end
preload(*args) click to toggle source

Allows preloading of args, in the same way that includes does:

User.preload(:posts)
# SELECT "posts".* FROM "posts" WHERE "posts"."user_id" IN (1, 2, 3)
# File lib/active_record/relation/query_methods.rb, line 180
def preload(*args)
  check_if_method_has_arguments!(:preload, args)
  spawn.preload!(*args)
end
readonly(value = true) click to toggle source

Sets readonly attributes for the returned relation. If value is true (default), attempting to update a record will result in an error.

users = User.readonly
users.first.save
=> ActiveRecord::ReadOnlyRecord: User is marked as readonly
# File lib/active_record/relation/query_methods.rb, line 837
def readonly(value = true)
  spawn.readonly!(value)
end
references(*table_names) click to toggle source

Use to indicate that the given table_names are referenced by an SQL string, and should therefore be JOINed in any query rather than loaded separately. This method only works in conjunction with includes. See includes for more details.

User.includes(:posts).where("posts.name = 'foo'")
# Doesn't JOIN the posts table, resulting in an error.

User.includes(:posts).where("posts.name = 'foo'").references(:posts)
# Query now knows the string references posts, so adds a JOIN
# File lib/active_record/relation/query_methods.rb, line 213
def references(*table_names)
  check_if_method_has_arguments!(:references, table_names)
  spawn.references!(*table_names)
end
reorder(*args) click to toggle source

Replaces any existing order defined on the relation with the specified order.

User.order('email DESC').reorder('id ASC') # generated SQL has 'ORDER BY id ASC'

Subsequent calls to order on the same relation will be appended. For example:

User.order('email DESC').reorder('id ASC').order('name ASC')

generates a query with 'ORDER BY id ASC, name ASC'.

# File lib/active_record/relation/query_methods.rb, line 374
def reorder(*args)
  check_if_method_has_arguments!(:reorder, args) do
    sanitize_order_arguments(args) unless args.all?(&:blank?)
  end
  spawn.reorder!(*args)
end
reselect(*args) click to toggle source

Allows you to change a previously set select statement.

Post.select(:title, :body)
# SELECT `posts`.`title`, `posts`.`body` FROM `posts`

Post.select(:title, :body).reselect(:created_at)
# SELECT `posts`.`created_at` FROM `posts`

This is short-hand for unscope(:select).select(fields). Note that we're unscoping the entire select statement.

# File lib/active_record/relation/query_methods.rb, line 291
def reselect(*args)
  check_if_method_has_arguments!(:reselect, args)
  spawn.reselect!(*args)
end
reverse_order() click to toggle source

Reverse the existing order clause on the relation.

User.order('name ASC').reverse_order # generated SQL has 'ORDER BY name DESC'
# File lib/active_record/relation/query_methods.rb, line 1009
def reverse_order
  spawn.reverse_order!
end
rewhere(conditions) click to toggle source

Allows you to change a previously set where condition for a given attribute, instead of appending to that condition.

Post.where(trashed: true).where(trashed: false)
# WHERE `trashed` = 1 AND `trashed` = 0

Post.where(trashed: true).rewhere(trashed: false)
# WHERE `trashed` = 0

Post.where(active: true).where(trashed: true).rewhere(trashed: false)
# WHERE `active` = 1 AND `trashed` = 0

This is short-hand for unscope(where: conditions.keys).where(conditions). Note that unlike reorder, we're only unscoping the named conditions – not the entire where statement.

# File lib/active_record/relation/query_methods.rb, line 662
def rewhere(conditions)
  scope = spawn
  where_clause = scope.build_where_clause(conditions)

  scope.unscope!(where: where_clause.extract_attributes)
  scope.where_clause += where_clause
  scope
end
select(*fields) click to toggle source

Works in two unique ways.

First: takes a block so it can be used just like Array#select.

Model.all.select { |m| m.field == value }

This will build an array of objects from the database for the scope, converting them into an array and iterating through them using Array#select.

Second: Modifies the SELECT statement for the query so that only certain fields are retrieved:

Model.select(:field)
# => [#<Model id: nil, field: "value">]

Although in the above example it looks as though this method returns an array, it actually returns a relation object and can have other query methods appended to it, such as the other methods in ActiveRecord::QueryMethods.

The argument to the method can also be an array of fields.

Model.select(:field, :other_field, :and_one_more)
# => [#<Model id: nil, field: "value", other_field: "value", and_one_more: "value">]

You can also use one or more strings, which will be used unchanged as SELECT fields.

Model.select('field AS field_one', 'other_field AS field_two')
# => [#<Model id: nil, field: "value", other_field: "value">]

If an alias was specified, it will be accessible from the resulting objects:

Model.select('field AS field_one').first.field_one
# => "value"

Accessing attributes of an object that do not have fields retrieved by a select except id will throw ActiveModel::MissingAttributeError:

Model.select(:field).first.other_field
# => ActiveModel::MissingAttributeError: missing attribute: other_field
Calls superclass method
# File lib/active_record/relation/query_methods.rb, line 263
def select(*fields)
  if block_given?
    if fields.any?
      raise ArgumentError, "`select' with block doesn't take arguments."
    end

    return super()
  end

  check_if_method_has_arguments!(:select, fields, "Call `select' with at least one field.")
  spawn._select!(*fields)
end
strict_loading(value = true) click to toggle source

Sets the returned relation to strict_loading mode. This will raise an error if the record tries to lazily load an association.

user = User.strict_loading.first
user.comments.to_a
=> ActiveRecord::StrictLoadingViolationError
# File lib/active_record/relation/query_methods.rb, line 852
def strict_loading(value = true)
  spawn.strict_loading!(value)
end
uniq!(name) click to toggle source

Deduplicate multiple values.

# File lib/active_record/relation/query_methods.rb, line 1052
def uniq!(name)
  if values = @values[name]
    values.uniq! if values.is_a?(Array) && !values.empty?
  end
  self
end
unscope(*args) click to toggle source

Removes an unwanted relation that is already defined on a chain of relations. This is useful when passing around chains of relations and would like to modify the relations without reconstructing the entire chain.

User.order('email DESC').unscope(:order) == User.all

The method arguments are symbols which correspond to the names of the methods which should be unscoped. The valid arguments are given in VALID_UNSCOPING_VALUES. The method can also be called with multiple arguments. For example:

User.order('email DESC').select('id').where(name: "John")
    .unscope(:order, :select, :where) == User.all

One can additionally pass a hash as an argument to unscope specific :where values. This is done by passing a hash with a single key-value pair. The key should be :where and the value should be the where value to unscope. For example:

User.where(name: "John", active: true).unscope(where: :name)
    == User.where(active: true)

This method is similar to except, but unlike except, it persists across merges:

User.order('email').merge(User.except(:order))
    == User.order('email')

User.order('email').merge(User.unscope(:order))
    == User.all

This means it can be used in association definitions:

has_many :comments, -> { unscope(where: :trashed) }
# File lib/active_record/relation/query_methods.rb, line 427
def unscope(*args)
  check_if_method_has_arguments!(:unscope, args)
  spawn.unscope!(*args)
end
where(*args) click to toggle source

Returns a new relation, which is the result of filtering the current relation according to the conditions in the arguments.

where accepts conditions in one of several formats. In the examples below, the resulting SQL is given as an illustration; the actual query generated may be different depending on the database adapter.

string

A single string, without additional arguments, is passed to the query constructor as an SQL fragment, and used in the where clause of the query.

Client.where("orders_count = '2'")
# SELECT * from clients where orders_count = '2';

Note that building your own string from user input may expose your application to injection attacks if not done properly. As an alternative, it is recommended to use one of the following methods.

array

If an array is passed, then the first element of the array is treated as a template, and the remaining elements are inserted into the template to generate the condition. Active Record takes care of building the query to avoid injection attacks, and will convert from the ruby type to the database type where needed. Elements are inserted into the string in the order in which they appear.

User.where(["name = ? and email = ?", "Joe", "joe@example.com"])
# SELECT * FROM users WHERE name = 'Joe' AND email = 'joe@example.com';

Alternatively, you can use named placeholders in the template, and pass a hash as the second element of the array. The names in the template are replaced with the corresponding values from the hash.

User.where(["name = :name and email = :email", { name: "Joe", email: "joe@example.com" }])
# SELECT * FROM users WHERE name = 'Joe' AND email = 'joe@example.com';

This can make for more readable code in complex queries.

Lastly, you can use sprintf-style % escapes in the template. This works slightly differently than the previous methods; you are responsible for ensuring that the values in the template are properly quoted. The values are passed to the connector for quoting, but the caller is responsible for ensuring they are enclosed in quotes in the resulting SQL. After quoting, the values are inserted using the same escapes as the Ruby core method Kernel::sprintf.

User.where(["name = '%s' and email = '%s'", "Joe", "joe@example.com"])
# SELECT * FROM users WHERE name = 'Joe' AND email = 'joe@example.com';

If where is called with multiple arguments, these are treated as if they were passed as the elements of a single array.

User.where("name = :name and email = :email", { name: "Joe", email: "joe@example.com" })
# SELECT * FROM users WHERE name = 'Joe' AND email = 'joe@example.com';

When using strings to specify conditions, you can use any operator available from the database. While this provides the most flexibility, you can also unintentionally introduce dependencies on the underlying database. If your code is intended for general consumption, test with multiple database backends.

hash

where will also accept a hash condition, in which the keys are fields and the values are values to be searched for.

Fields can be symbols or strings. Values can be single values, arrays, or ranges.

User.where({ name: "Joe", email: "joe@example.com" })
# SELECT * FROM users WHERE name = 'Joe' AND email = 'joe@example.com'

User.where({ name: ["Alice", "Bob"]})
# SELECT * FROM users WHERE name IN ('Alice', 'Bob')

User.where({ created_at: (Time.now.midnight - 1.day)..Time.now.midnight })
# SELECT * FROM users WHERE (created_at BETWEEN '2012-06-09 07:00:00.000000' AND '2012-06-10 07:00:00.000000')

In the case of a belongs_to relationship, an association key can be used to specify the model if an ActiveRecord object is used as the value.

author = Author.find(1)

# The following queries will be equivalent:
Post.where(author: author)
Post.where(author_id: author)

This also works with polymorphic belongs_to relationships:

treasure = Treasure.create(name: 'gold coins')
treasure.price_estimates << PriceEstimate.create(price: 125)

# The following queries will be equivalent:
PriceEstimate.where(estimate_of: treasure)
PriceEstimate.where(estimate_of_type: 'Treasure', estimate_of_id: treasure)

Joins

If the relation is the result of a join, you may create a condition which uses any of the tables in the join. For string and array conditions, use the table name in the condition.

User.joins(:posts).where("posts.created_at < ?", Time.now)

For hash conditions, you can either use the table name in the key, or use a sub-hash.

User.joins(:posts).where({ "posts.published" => true })
User.joins(:posts).where({ posts: { published: true } })

no argument

If no argument is passed, where returns a new instance of WhereChain, that can be chained with not to return a new relation that negates the where clause.

User.where.not(name: "Jon")
# SELECT * FROM users WHERE name != 'Jon'

See WhereChain for more details on not.

blank condition

If the condition is any blank-ish object, then where is a no-op and returns the current relation.

# File lib/active_record/relation/query_methods.rb, line 634
def where(*args)
  if args.empty?
    WhereChain.new(spawn)
  elsif args.length == 1 && args.first.blank?
    self
  else
    spawn.where!(*args)
  end
end

Private Instance Methods

arel_column(field) { |field| ... } click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1311
def arel_column(field)
  field = klass.attribute_aliases[field] || field
  from = from_clause.name || from_clause.value

  if klass.columns_hash.key?(field) && (!from || table_name_matches?(from))
    table[field]
  elsif field.match?(/\A\w+\.\w+\z/)
    table, column = field.split(".")
    predicate_builder.resolve_arel_attribute(table, column) do
      lookup_table_klass_from_join_dependencies(table)
    end
  else
    yield field
  end
end
arel_columns(columns) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1294
def arel_columns(columns)
  columns.flat_map do |field|
    case field
    when Symbol
      arel_column(field.to_s) do |attr_name|
        connection.quote_table_name(attr_name)
      end
    when String
      arel_column(field, &:itself)
    when Proc
      field.call
    else
      field
    end
  end
end
assert_mutability!() click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1133
def assert_mutability!
  raise ImmutableRelation if @loaded
  raise ImmutableRelation if defined?(@arel) && @arel
end
build_arel(aliases = nil) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1138
      def build_arel(aliases = nil)
        arel = Arel::SelectManager.new(table)

        build_joins(arel.join_sources, aliases)

        arel.where(where_clause.ast) unless where_clause.empty?
        arel.having(having_clause.ast) unless having_clause.empty?
        arel.take(build_cast_value("LIMIT", connection.sanitize_limit(limit_value))) if limit_value
        arel.skip(build_cast_value("OFFSET", offset_value.to_i)) if offset_value
        arel.group(*arel_columns(group_values.uniq)) unless group_values.empty?

        build_order(arel)
        build_select(arel)

        arel.optimizer_hints(*optimizer_hints_values) unless optimizer_hints_values.empty?
        arel.distinct(distinct_value)
        arel.from(build_from) unless from_clause.empty?
        arel.lock(lock_value) if lock_value

        unless annotate_values.empty?
          annotates = annotate_values
          annotates = annotates.uniq if annotates.size > 1
          unless annotates == annotate_values
            ActiveSupport::Deprecation.warn(<<-MSG.squish)
              Duplicated query annotations are no longer shown in queries in Rails 7.0.
              To migrate to Rails 7.0's behavior, use `uniq!(:annotate)` to deduplicate query annotations
              (`#{klass.name&.tableize || klass.table_name}.uniq!(:annotate)`).
            MSG
            annotates = annotate_values
          end
          arel.comment(*annotates)
        end

        arel
      end
build_cast_value(name, value) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1174
def build_cast_value(name, value)
  cast_value = ActiveModel::Attribute.with_cast_value(name, value, Type.default_value)
  Arel::Nodes::BindParam.new(cast_value)
end
build_from() click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1179
def build_from
  opts = from_clause.value
  name = from_clause.name
  case opts
  when Relation
    if opts.eager_loading?
      opts = opts.send(:apply_join_dependency)
    end
    name ||= "subquery"
    opts.arel.as(name.to_s)
  else
    opts
  end
end
build_join_buckets() click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1212
def build_join_buckets
  buckets = Hash.new { |h, k| h[k] = [] }

  unless left_outer_joins_values.empty?
    stashed_left_joins = []
    left_joins = select_association_list(left_outer_joins_values, stashed_left_joins) do
      raise ArgumentError, "only Hash, Symbol and Array are allowed"
    end

    if joins_values.empty?
      buckets[:association_join] = left_joins
      buckets[:stashed_join] = stashed_left_joins
      return buckets, Arel::Nodes::OuterJoin
    else
      stashed_left_joins.unshift construct_join_dependency(left_joins, Arel::Nodes::OuterJoin)
    end
  end

  joins = joins_values.dup
  if joins.last.is_a?(ActiveRecord::Associations::JoinDependency)
    stashed_eager_load = joins.pop if joins.last.base_klass == klass
  end

  joins.each_with_index do |join, i|
    joins[i] = Arel::Nodes::StringJoin.new(Arel.sql(join.strip)) if join.is_a?(String)
  end

  while joins.first.is_a?(Arel::Nodes::Join)
    join_node = joins.shift
    if !join_node.is_a?(Arel::Nodes::LeadingJoin) && (stashed_eager_load || stashed_left_joins)
      buckets[:join_node] << join_node
    else
      buckets[:leading_join] << join_node
    end
  end

  buckets[:association_join] = select_association_list(joins, buckets[:stashed_join]) do |join|
    if join.is_a?(Arel::Nodes::Join)
      buckets[:join_node] << join
    else
      raise "unknown class: %s" % join.class.name
    end
  end

  buckets[:stashed_join].concat stashed_left_joins if stashed_left_joins
  buckets[:stashed_join] << stashed_eager_load if stashed_eager_load

  return buckets, Arel::Nodes::InnerJoin
end
build_join_dependencies() click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1122
def build_join_dependencies
  associations = joins_values | left_outer_joins_values
  associations |= eager_load_values unless eager_load_values.empty?
  associations |= includes_values unless includes_values.empty?

  join_dependencies = []
  join_dependencies.unshift construct_join_dependency(
    select_association_list(associations, join_dependencies), nil
  )
end
build_joins(join_sources, aliases = nil) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1262
def build_joins(join_sources, aliases = nil)
  return join_sources if joins_values.empty? && left_outer_joins_values.empty?

  buckets, join_type = build_join_buckets

  association_joins = buckets[:association_join]
  stashed_joins     = buckets[:stashed_join]
  leading_joins     = buckets[:leading_join]
  join_nodes        = buckets[:join_node]

  join_sources.concat(leading_joins) unless leading_joins.empty?

  unless association_joins.empty? && stashed_joins.empty?
    alias_tracker = alias_tracker(leading_joins + join_nodes, aliases)
    join_dependency = construct_join_dependency(association_joins, join_type)
    join_sources.concat(join_dependency.join_constraints(stashed_joins, alias_tracker, references_values))
  end

  join_sources.concat(join_nodes) unless join_nodes.empty?
  join_sources
end
build_order(arel) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1373
def build_order(arel)
  orders = order_values.compact_blank
  arel.order(*orders) unless orders.empty?
end
build_select(arel) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1284
def build_select(arel)
  if select_values.any?
    arel.project(*arel_columns(select_values))
  elsif klass.ignored_columns.any?
    arel.project(*klass.column_names.map { |field| table[field] })
  else
    arel.project(table[Arel.star])
  end
end
check_if_method_has_arguments!(method_name, args, message = nil) { |args| ... } click to toggle source

Checks to make sure that the arguments are not blank. Note that if some blank-like object were initially passed into the query method, then this method will not raise an error.

Example:

Post.references()   # raises an error
Post.references([]) # does not raise an error

This particular method should be called with a method_name and the args passed into that method as an input. For example:

def references(*args)

check_if_method_has_arguments!("references", args)
...

end

# File lib/active_record/relation/query_methods.rb, line 1488
def check_if_method_has_arguments!(method_name, args, message = nil)
  if args.blank?
    raise ArgumentError, message || "The method .#{method_name}() must contain arguments."
  elsif block_given?
    yield args
  else
    args.flatten!
    args.compact_blank!
  end
end
column_references(order_args) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1432
def column_references(order_args)
  references = order_args.grep(String)
  references.map! { |arg| arg =~ /^\W?(\w+)\W?\./ && $1 }.compact!
  references
end
does_not_support_reverse?(order) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1362
def does_not_support_reverse?(order)
  # Account for String subclasses like Arel::Nodes::SqlLiteral that
  # override methods like #count.
  order = String.new(order) unless order.instance_of?(String)

  # Uses SQL function with multiple arguments.
  (order.include?(",") && order.split(",").find { |section| section.count("(") != section.count(")") }) ||
    # Uses "nulls first" like construction.
    /\bnulls\s+(?:first|last)\b/i.match?(order)
end
each_join_dependencies(join_dependencies = build_join_dependencies) { |join| ... } click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1114
def each_join_dependencies(join_dependencies = build_join_dependencies)
  join_dependencies.each do |join_dependency|
    join_dependency.each do |join|
      yield join
    end
  end
end
lookup_table_klass_from_join_dependencies(table_name) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1107
def lookup_table_klass_from_join_dependencies(table_name)
  each_join_dependencies do |join|
    return join.base_klass if table_name == join.table_name
  end
  nil
end
order_column(field) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1438
def order_column(field)
  arel_column(field) do |attr_name|
    if attr_name == "count" && !group_values.empty?
      table[attr_name]
    else
      Arel.sql(connection.quote_table_name(attr_name))
    end
  end
end
preprocess_order_args(order_args) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1393
def preprocess_order_args(order_args)
  @klass.disallow_raw_sql!(
    order_args.flat_map { |a| a.is_a?(Hash) ? a.keys : a },
    permit: connection.column_name_with_order_matcher
  )

  validate_order_args(order_args)

  references = column_references(order_args)
  self.references_values |= references unless references.empty?

  # if a symbol is given we prepend the quoted table name
  order_args.map! do |arg|
    case arg
    when Symbol
      order_column(arg.to_s).asc
    when Hash
      arg.map { |field, dir|
        case field
        when Arel::Nodes::SqlLiteral
          field.public_send(dir.downcase)
        else
          order_column(field.to_s).public_send(dir.downcase)
        end
      }
    else
      arg
    end
  end.flatten!
end
resolve_arel_attributes(attrs) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1448
def resolve_arel_attributes(attrs)
  attrs.flat_map do |attr|
    case attr
    when Arel::Predications
      attr
    when Hash
      attr.flat_map do |table, columns|
        table = table.to_s
        Array(columns).map do |column|
          predicate_builder.resolve_arel_attribute(table, column)
        end
      end
    else
      attr = attr.to_s
      if attr.include?(".")
        table, column = attr.split(".", 2)
        predicate_builder.resolve_arel_attribute(table, column)
      else
        attr
      end
    end
  end
end
reverse_sql_order(order_query) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1333
def reverse_sql_order(order_query)
  if order_query.empty?
    return [table[primary_key].desc] if primary_key
    raise IrreversibleOrderError,
      "Relation has no current order and table has no primary key to be used as default order"
  end

  order_query.flat_map do |o|
    case o
    when Arel::Attribute
      o.desc
    when Arel::Nodes::Ordering
      o.reverse
    when Arel::Nodes::NodeExpression
      o.desc
    when String
      if does_not_support_reverse?(o)
        raise IrreversibleOrderError, "Order #{o.inspect} cannot be reversed automatically"
      end
      o.split(",").map! do |s|
        s.strip!
        s.gsub!(/\sasc\Z/i, " DESC") || s.gsub!(/\sdesc\Z/i, " ASC") || (s << " DESC")
      end
    else
      o
    end
  end
end
sanitize_order_arguments(order_args) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1424
def sanitize_order_arguments(order_args)
  order_args.map! do |arg|
    klass.sanitize_sql_for_order(arg)
  end
  order_args.flatten!
  order_args.compact_blank!
end
select_association_list(associations, stashed_joins = nil) { |association| ... } click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1194
def select_association_list(associations, stashed_joins = nil)
  result = []
  associations.each do |association|
    case association
    when Hash, Symbol, Array
      result << association
    when ActiveRecord::Associations::JoinDependency
      stashed_joins&.<< association
    else
      yield association if block_given?
    end
  end
  result
end
structurally_incompatible_values_for(other) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1504
def structurally_incompatible_values_for(other)
  values = other.values
  STRUCTURAL_VALUE_METHODS.reject do |method|
    v1, v2 = @values[method], values[method]
    if v1.is_a?(Array)
      next true unless v2.is_a?(Array)
      v1 = v1.uniq
      v2 = v2.uniq
    end
    v1 == v2
  end
end
table_name_matches?(from) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1327
def table_name_matches?(from)
  table_name = Regexp.escape(table.name)
  quoted_table_name = Regexp.escape(connection.quote_table_name(table.name))
  /(?:\A|(?<!FROM)\s)(?:\b#{table_name}\b|#{quoted_table_name})(?!\.)/i.match?(from.to_s)
end
validate_order_args(args) click to toggle source
# File lib/active_record/relation/query_methods.rb, line 1381
def validate_order_args(args)
  args.each do |arg|
    next unless arg.is_a?(Hash)
    arg.each do |_key, value|
      unless VALID_DIRECTIONS.include?(value)
        raise ArgumentError,
          "Direction \"#{value}\" is invalid. Valid directions are: #{VALID_DIRECTIONS.to_a.inspect}"
      end
    end
  end
end