# module ActiveRecord::QueryMethods

### Constants

FROZEN_EMPTY_ARRAY
FROZEN_EMPTY_HASH
STRUCTURAL_OR_METHODS
VALID_UNSCOPING_VALUES

### Public Instance Methods

bound_attributes() click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 77
    def bound_attributes
      if limit_value
        limit_bind = Attribute.with_cast_value(
          "LIMIT".freeze,
          connection.sanitize_limit(limit_value),
          Type.default_value,
        )
      end
      if offset_value
        offset_bind = Attribute.with_cast_value(
          "OFFSET".freeze,
          offset_value.to_i,
          Type.default_value,
        )
      end
      connection.combine_bind_parameters(
        from_clause: from_clause.binds,
        join_clause: arel.bind_values,
        where_clause: where_clause.binds,
        having_clause: having_clause.binds,
        limit: limit_bind,
        offset: offset_bind,
      )
    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 791
    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 838
    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 156
    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 884
    def extending(*modules, &block)
      if modules.any? || block
        spawn.extending!(*modules, &block)
      else
        self
      end
    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 819
    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 284
    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 668
    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 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.

    # File lib/active_record/relation/query_methods.rb, line 137
    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" "comments_posts"
    #   ON "comments_posts"."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 448
    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 465
    def left_outer_joins(*args)
      check_if_method_has_arguments!(:left_outer_joins, args)

      args.compact!
      args.flatten!

      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 685
    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 712
    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 755
    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 701
    def offset(value)
      spawn.offset!(value)
    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). Neither relation may have a limit, offset, or distinct set.

    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 643
    def or(other)
      unless other.is_a? Relation
        raise ArgumentError, "You have passed #{other.class.name} object to #or. Pass an ActiveRecord::Relation object instead."
      end

      spawn.or!(other)
    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 315
    def order(*args)
      check_if_method_has_arguments!(:order, args)
      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 170
    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 769
    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 190
    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 336
    def reorder(*args)
      check_if_method_has_arguments!(:reorder, args)
      spawn.reorder!(*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 905
    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 629
    def rewhere(conditions)
      unscope(where: conditions.keys).where(conditions)
    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 242
    def select(*fields)
      if block_given?
        if fields.any?
          raise ArgumentError, "`select' with block doesn't take arguments."
        end

        return super()
      end

      raise ArgumentError, "Call this with at least one field" if fields.empty?
      spawn._select!(*fields)
    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 386
    def unscope(*args)
      check_if_method_has_arguments!(:unscope, args)
      spawn.unscope!(*args)
    end

where(opts = :chain, *rest) 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 599
    def where(opts = :chain, *rest)
      if :chain == opts
        WhereChain.new(spawn)
      elsif opts.blank?
        self
      else
        spawn.where!(opts, *rest)
      end
    end

### Private Instance Methods

arel_columns(columns) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1049
    def arel_columns(columns)
      columns.map do |field|
        if (Symbol === field || String === field) && (klass.has_attribute?(field) || klass.attribute_alias?(field)) && !from_clause.value
          arel_attribute(field)
        elsif Symbol === field
          connection.quote_table_name(field.to_s)
        else
          field
        end
      end
    end

assert_mutability!() click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 934
    def assert_mutability!
      raise ImmutableRelation if @loaded
      raise ImmutableRelation if defined?(@arel) && @arel
    end

build_arel() click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 939
    def build_arel
      arel = Arel::SelectManager.new(table)

      build_joins(arel, joins_values.flatten) unless joins_values.empty?
      build_left_outer_joins(arel, left_outer_joins_values.flatten) unless left_outer_joins_values.empty?

      arel.where(where_clause.ast) unless where_clause.empty?
      arel.having(having_clause.ast) unless having_clause.empty?
      arel.take(Arel::Nodes::BindParam.new) if limit_value
      arel.skip(Arel::Nodes::BindParam.new) if offset_value
      arel.group(*arel_columns(group_values.uniq.reject(&:blank?))) unless group_values.empty?

      build_order(arel)

      build_select(arel)

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

      arel
    end

build_from() click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 962
    def build_from
      opts = from_clause.value
      name = from_clause.name
      case opts
      when Relation
        name ||= "subquery"
        opts.arel.as(name.to_s)
      else
        opts
      end
    end

build_join_query(manager, buckets, join_type) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1006
    def build_join_query(manager, buckets, join_type)
      buckets.default = []

      association_joins         = buckets[:association_join]
      stashed_association_joins = buckets[:stashed_join]
      join_nodes                = buckets[:join_node].uniq
      string_joins              = buckets[:string_join].map(&:strip).uniq

      join_list = join_nodes + convert_join_strings_to_ast(manager, string_joins)

      join_dependency = ActiveRecord::Associations::JoinDependency.new(
        @klass,
        association_joins,
        join_list
      )

      join_infos = join_dependency.join_constraints stashed_association_joins, join_type

      join_infos.each do |info|
        info.joins.each { |join| manager.from(join) }
        manager.bind_values.concat info.binds
      end

      manager.join_sources.concat(join_list)

      manager
    end

build_joins(manager, joins) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 987
    def build_joins(manager, joins)
      buckets = joins.group_by do |join|
        case join
        when String
          :string_join
        when Hash, Symbol, Array
          :association_join
        when ActiveRecord::Associations::JoinDependency
          :stashed_join
        when Arel::Nodes::Join
          :join_node
        else
          raise "unknown class: %s" % join.class.name
        end
      end

      build_join_query(manager, buckets, Arel::Nodes::InnerJoin)
    end

build_left_outer_joins(manager, outer_joins) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 974
    def build_left_outer_joins(manager, outer_joins)
      buckets = outer_joins.group_by do |join|
        case join
        when Hash, Symbol, Array
          :association_join
        else
          raise ArgumentError, "only Hash, Symbol and Array are allowed"
        end
      end

      build_join_query(manager, buckets, Arel::Nodes::OuterJoin)
    end

build_order(arel) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1095
    def build_order(arel)
      orders = order_values.uniq
      orders.reject!(&:blank?)

      arel.order(*orders) unless orders.empty?
    end

build_select(arel) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1041
    def build_select(arel)
      if select_values.any?
        arel.project(*arel_columns(select_values.uniq))
      else
        arel.project(@klass.arel_table[Arel.star])
      end
    end

check_if_method_has_arguments!(method_name, 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 1162
    def check_if_method_has_arguments!(method_name, args)
      if args.blank?
        raise ArgumentError, "The method .#{method_name}() must contain arguments."
      end
    end

convert_join_strings_to_ast(table, joins) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1034
    def convert_join_strings_to_ast(table, joins)
      joins
        .flatten
        .reject(&:blank?)
        .map { |join| table.create_string_join(Arel.sql(join)) }
    end

default_value_for(name) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1180
    def default_value_for(name)
      case name
      when :create_with
        FROZEN_EMPTY_HASH
      when :readonly
        false
      when :where, :having
        Relation::WhereClause.empty
      when :from
        Relation::FromClause.empty
      when *Relation::MULTI_VALUE_METHODS
        FROZEN_EMPTY_ARRAY
      when *Relation::SINGLE_VALUE_METHODS
        nil
      else
        raise ArgumentError, "unknown relation value #{name.inspect}"
      end
    end

does_not_support_reverse?(order) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1088
    def does_not_support_reverse?(order)
      # Uses SQL function with multiple arguments.
      (order.include?(",") && order.split(",").find { |section| section.count("(") != section.count(")") }) ||
        # Uses "nulls first" like construction.
        /nulls (first|last)\Z/i.match?(order)
    end

having_clause_factory()
Alias for: where_clause_factory
preprocess_order_args(order_args) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1115
    def preprocess_order_args(order_args)
      order_args.map! do |arg|
        klass.send(:sanitize_sql_for_order, arg)
      end
      order_args.flatten!
      validate_order_args(order_args)

      references = order_args.grep(String)
      references.map! { |arg| arg =~ /^([a-zA-Z]\w*)\.(\w+)/ && $1 }.compact!
      references!(references) if references.any?

      # if a symbol is given we prepend the quoted table name
      order_args.map! do |arg|
        case arg
        when Symbol
          arel_attribute(arg).asc
        when Hash
          arg.map { |field, dir|
            case field
            when Arel::Nodes::SqlLiteral
              field.send(dir.downcase)
            else
              arel_attribute(field).send(dir.downcase)
            end
          }
        else
          arg
        end
      end.flatten!
    end

reverse_sql_order(order_query) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1061
    def reverse_sql_order(order_query)
      if order_query.empty?
        return [arel_attribute(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 String
          if does_not_support_reverse?(o)
            raise IrreversibleOrderError, "Order #{o.inspect} can not be reversed automatically"
          end
          o.split(",").map! do |s|
            s.strip!
            s.gsub!(/\sasc\Z/i, " DESC") || s.gsub!(/\sdesc\Z/i, " ASC") || s.concat(" DESC")
          end
        else
          o
        end
      end
    end

structurally_incompatible_values_for_or(other) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1169
    def structurally_incompatible_values_for_or(other)
      STRUCTURAL_OR_METHODS.reject do |method|
        get_value(method) == other.get_value(method)
      end
    end

validate_order_args(args) click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1105
    def validate_order_args(args)
      args.each do |arg|
        next unless arg.is_a?(Hash)
        arg.each do |_key, value|
          raise ArgumentError, "Direction \"#{value}\" is invalid. Valid "                                   "directions are: #{VALID_DIRECTIONS.inspect}" unless VALID_DIRECTIONS.include?(value)
        end
      end
    end

where_clause_factory() click to toggle source

    # File lib/active_record/relation/query_methods.rb, line 1175
    def where_clause_factory
      @where_clause_factory ||= Relation::WhereClauseFactory.new(klass, predicate_builder)
    end

Also aliased as: having_clause_factory