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627 lines
21 KiB
Ruby
627 lines
21 KiB
Ruby
# -*- coding: utf-8 -*-
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module ActiveRecord
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# = Active Record Relation
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class Relation
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JoinOperation = Struct.new(:relation, :join_class, :on)
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MULTI_VALUE_METHODS = [:includes, :eager_load, :preload, :select, :group,
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:order, :joins, :where, :having, :bind, :references,
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:extending]
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SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :from, :reordering,
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:reverse_order, :distinct, :create_with, :uniq]
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VALUE_METHODS = MULTI_VALUE_METHODS + SINGLE_VALUE_METHODS
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include FinderMethods, Calculations, SpawnMethods, QueryMethods, Batches, Explain, Delegation
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attr_reader :table, :klass, :loaded
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alias :model :klass
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alias :loaded? :loaded
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def initialize(klass, table, values = {})
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@klass = klass
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@table = table
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@values = values
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@loaded = false
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end
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def initialize_copy(other)
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# This method is a hot spot, so for now, use Hash[] to dup the hash.
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# https://bugs.ruby-lang.org/issues/7166
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@values = Hash[@values]
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@values[:bind] = @values[:bind].dup if @values.key? :bind
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reset
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end
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def insert(values) # :nodoc:
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primary_key_value = nil
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if primary_key && Hash === values
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primary_key_value = values[values.keys.find { |k|
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k.name == primary_key
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}]
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if !primary_key_value && connection.prefetch_primary_key?(klass.table_name)
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primary_key_value = connection.next_sequence_value(klass.sequence_name)
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values[klass.arel_table[klass.primary_key]] = primary_key_value
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end
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end
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im = arel.create_insert
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im.into @table
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substitutes, binds = substitute_values values
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if values.empty? # empty insert
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im.values = Arel.sql(connection.empty_insert_statement_value)
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else
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im.insert substitutes
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end
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@klass.connection.insert(
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im,
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'SQL',
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primary_key,
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primary_key_value,
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nil,
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binds)
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end
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def update_record(values, id, id_was) # :nodoc:
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substitutes, binds = substitute_values values
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um = @klass.unscoped.where(@klass.arel_table[@klass.primary_key].eq(id_was || id)).arel.compile_update(substitutes)
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@klass.connection.update(
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um,
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'SQL',
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binds)
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end
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def substitute_values(values) # :nodoc:
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substitutes = values.sort_by { |arel_attr,_| arel_attr.name }
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binds = substitutes.map do |arel_attr, value|
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[@klass.columns_hash[arel_attr.name], value]
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end
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substitutes.each_with_index do |tuple, i|
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tuple[1] = @klass.connection.substitute_at(binds[i][0], i)
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end
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[substitutes, binds]
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end
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# Initializes new record from relation while maintaining the current
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# scope.
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#
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# Expects arguments in the same format as +Base.new+.
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#
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# users = User.where(name: 'DHH')
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# user = users.new # => #<User id: nil, name: "DHH", created_at: nil, updated_at: nil>
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#
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# You can also pass a block to new with the new record as argument:
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#
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# user = users.new { |user| user.name = 'Oscar' }
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# user.name # => Oscar
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def new(*args, &block)
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scoping { @klass.new(*args, &block) }
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end
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alias build new
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# Tries to create a new record with the same scoped attributes
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# defined in the relation. Returns the initialized object if validation fails.
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#
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# Expects arguments in the same format as +Base.create+.
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#
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# ==== Examples
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# users = User.where(name: 'Oscar')
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# users.create # #<User id: 3, name: "oscar", ...>
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#
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# users.create(name: 'fxn')
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# users.create # #<User id: 4, name: "fxn", ...>
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#
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# users.create { |user| user.name = 'tenderlove' }
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# # #<User id: 5, name: "tenderlove", ...>
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#
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# users.create(name: nil) # validation on name
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# # #<User id: nil, name: nil, ...>
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def create(*args, &block)
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scoping { @klass.create(*args, &block) }
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end
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# Similar to #create, but calls +create!+ on the base class. Raises
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# an exception if a validation error occurs.
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#
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# Expects arguments in the same format as <tt>Base.create!</tt>.
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def create!(*args, &block)
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scoping { @klass.create!(*args, &block) }
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end
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def first_or_create(attributes = nil, &block) # :nodoc:
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first || create(attributes, &block)
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end
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def first_or_create!(attributes = nil, &block) # :nodoc:
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first || create!(attributes, &block)
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end
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def first_or_initialize(attributes = nil, &block) # :nodoc:
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first || new(attributes, &block)
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end
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# Finds the first record with the given attributes, or creates a record
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# with the attributes if one is not found:
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#
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# # Find the first user named "Penélope" or create a new one.
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# User.find_or_create_by(first_name: 'Penélope')
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# # => #<User id: 1, first_name: "Penélope", last_name: nil>
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#
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# # Find the first user named "Penélope" or create a new one.
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# # We already have one so the existing record will be returned.
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# User.find_or_create_by(first_name: 'Penélope')
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# # => #<User id: 1, first_name: "Penélope", last_name: nil>
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#
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# # Find the first user named "Scarlett" or create a new one with
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# # a particular last name.
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# User.create_with(last_name: 'Johansson').find_or_create_by(first_name: 'Scarlett')
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# # => #<User id: 2, first_name: "Scarlett", last_name: "Johansson">
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#
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# This method accepts a block, which is passed down to +create+. The last example
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# above can be alternatively written this way:
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#
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# # Find the first user named "Scarlett" or create a new one with a
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# # different last name.
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# User.find_or_create_by(first_name: 'Scarlett') do |user|
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# user.last_name = 'Johansson'
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# end
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# # => #<User id: 2, first_name: "Scarlett", last_name: "Johansson">
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#
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# This method always returns a record, but if creation was attempted and
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# failed due to validation errors it won't be persisted, you get what
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# +create+ returns in such situation.
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#
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# Please note *this method is not atomic*, it runs first a SELECT, and if
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# there are no results an INSERT is attempted. If there are other threads
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# or processes there is a race condition between both calls and it could
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# be the case that you end up with two similar records.
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#
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# Whether that is a problem or not depends on the logic of the
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# application, but in the particular case in which rows have a UNIQUE
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# constraint an exception may be raised, just retry:
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#
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# begin
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# CreditAccount.find_or_create_by(user_id: user.id)
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# rescue ActiveRecord::RecordNotUnique
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# retry
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# end
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#
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def find_or_create_by(attributes, &block)
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find_by(attributes) || create(attributes, &block)
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end
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# Like <tt>find_or_create_by</tt>, but calls <tt>create!</tt> so an exception
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# is raised if the created record is invalid.
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def find_or_create_by!(attributes, &block)
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find_by(attributes) || create!(attributes, &block)
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end
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# Like <tt>find_or_create_by</tt>, but calls <tt>new</tt> instead of <tt>create</tt>.
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def find_or_initialize_by(attributes, &block)
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find_by(attributes) || new(attributes, &block)
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end
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# Runs EXPLAIN on the query or queries triggered by this relation and
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# returns the result as a string. The string is formatted imitating the
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# ones printed by the database shell.
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#
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# Note that this method actually runs the queries, since the results of some
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# are needed by the next ones when eager loading is going on.
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#
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# Please see further details in the
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# {Active Record Query Interface guide}[http://guides.rubyonrails.org/active_record_querying.html#running-explain].
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def explain
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exec_explain(collecting_queries_for_explain { exec_queries })
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end
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# Converts relation objects to Array.
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def to_a
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load
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@records
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end
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def as_json(options = nil) #:nodoc:
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to_a.as_json(options)
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end
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# Returns size of the records.
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def size
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loaded? ? @records.length : count
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end
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# Returns true if there are no records.
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def empty?
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return @records.empty? if loaded?
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c = count(:all)
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c.respond_to?(:zero?) ? c.zero? : c.empty?
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end
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# Returns true if there are any records.
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def any?
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if block_given?
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to_a.any? { |*block_args| yield(*block_args) }
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else
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!empty?
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end
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end
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# Returns true if there is more than one record.
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def many?
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if block_given?
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to_a.many? { |*block_args| yield(*block_args) }
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else
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limit_value ? to_a.many? : size > 1
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end
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end
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# Scope all queries to the current scope.
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#
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# Comment.where(post_id: 1).scoping do
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# Comment.first
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# end
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# # => SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = 1 ORDER BY "comments"."id" ASC LIMIT 1
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#
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# Please check unscoped if you want to remove all previous scopes (including
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# the default_scope) during the execution of a block.
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def scoping
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previous, klass.current_scope = klass.current_scope, self
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yield
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ensure
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klass.current_scope = previous
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end
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# Updates all records with details given if they match a set of conditions supplied, limits and order can
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# also be supplied. This method constructs a single SQL UPDATE statement and sends it straight to the
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# database. It does not instantiate the involved models and it does not trigger Active Record callbacks
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# or validations.
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#
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# ==== Parameters
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#
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# * +updates+ - A string, array, or hash representing the SET part of an SQL statement.
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#
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# ==== Examples
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#
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# # Update all customers with the given attributes
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# Customer.update_all wants_email: true
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#
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# # Update all books with 'Rails' in their title
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# Book.where('title LIKE ?', '%Rails%').update_all(author: 'David')
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#
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# # Update all books that match conditions, but limit it to 5 ordered by date
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# Book.where('title LIKE ?', '%Rails%').order(:created_at).limit(5).update_all(author: 'David')
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def update_all(updates)
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raise ArgumentError, "Empty list of attributes to change" if updates.blank?
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stmt = Arel::UpdateManager.new(arel.engine)
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stmt.set Arel.sql(@klass.send(:sanitize_sql_for_assignment, updates))
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stmt.table(table)
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stmt.key = table[primary_key]
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if joins_values.any?
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@klass.connection.join_to_update(stmt, arel)
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else
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stmt.take(arel.limit)
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stmt.order(*arel.orders)
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stmt.wheres = arel.constraints
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end
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@klass.connection.update stmt, 'SQL', bind_values
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end
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# Updates an object (or multiple objects) and saves it to the database, if validations pass.
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# The resulting object is returned whether the object was saved successfully to the database or not.
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#
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# ==== Parameters
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#
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# * +id+ - This should be the id or an array of ids to be updated.
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# * +attributes+ - This should be a hash of attributes or an array of hashes.
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#
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# ==== Examples
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#
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# # Updates one record
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# Person.update(15, user_name: 'Samuel', group: 'expert')
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#
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# # Updates multiple records
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# people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
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# Person.update(people.keys, people.values)
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def update(id, attributes)
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if id.is_a?(Array)
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id.map.with_index { |one_id, idx| update(one_id, attributes[idx]) }
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else
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object = find(id)
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object.update(attributes)
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object
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end
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end
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# Destroys the records matching +conditions+ by instantiating each
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# record and calling its +destroy+ method. Each object's callbacks are
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# executed (including <tt>:dependent</tt> association options). Returns the
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# collection of objects that were destroyed; each will be frozen, to
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# reflect that no changes should be made (since they can't be persisted).
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#
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# Note: Instantiation, callback execution, and deletion of each
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# record can be time consuming when you're removing many records at
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# once. It generates at least one SQL +DELETE+ query per record (or
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# possibly more, to enforce your callbacks). If you want to delete many
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# rows quickly, without concern for their associations or callbacks, use
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# +delete_all+ instead.
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#
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# ==== Parameters
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#
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# * +conditions+ - A string, array, or hash that specifies which records
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# to destroy. If omitted, all records are destroyed. See the
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# Conditions section in the introduction to ActiveRecord::Base for
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# more information.
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#
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# ==== Examples
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#
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# Person.destroy_all("last_login < '2004-04-04'")
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# Person.destroy_all(status: "inactive")
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# Person.where(age: 0..18).destroy_all
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def destroy_all(conditions = nil)
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if conditions
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where(conditions).destroy_all
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else
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to_a.each {|object| object.destroy }.tap { reset }
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end
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end
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# Destroy an object (or multiple objects) that has the given id. The object is instantiated first,
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# therefore all callbacks and filters are fired off before the object is deleted. This method is
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# less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.
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#
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# This essentially finds the object (or multiple objects) with the given id, creates a new object
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# from the attributes, and then calls destroy on it.
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#
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# ==== Parameters
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#
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# * +id+ - Can be either an Integer or an Array of Integers.
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#
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# ==== Examples
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#
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# # Destroy a single object
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# Todo.destroy(1)
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#
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# # Destroy multiple objects
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# todos = [1,2,3]
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# Todo.destroy(todos)
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def destroy(id)
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if id.is_a?(Array)
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id.map { |one_id| destroy(one_id) }
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else
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find(id).destroy
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end
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end
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# Deletes the records matching +conditions+ without instantiating the records
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# first, and hence not calling the +destroy+ method nor invoking callbacks. This
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# is a single SQL DELETE statement that goes straight to the database, much more
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# efficient than +destroy_all+. Be careful with relations though, in particular
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# <tt>:dependent</tt> rules defined on associations are not honored. Returns the
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# number of rows affected.
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#
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# Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')")
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# Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])
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# Post.where(person_id: 5).where(category: ['Something', 'Else']).delete_all
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#
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# Both calls delete the affected posts all at once with a single DELETE statement.
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# If you need to destroy dependent associations or call your <tt>before_*</tt> or
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# +after_destroy+ callbacks, use the +destroy_all+ method instead.
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#
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# If a limit scope is supplied, +delete_all+ raises an ActiveRecord error:
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#
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# Post.limit(100).delete_all
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# # => ActiveRecord::ActiveRecordError: delete_all doesn't support limit scope
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def delete_all(conditions = nil)
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raise ActiveRecordError.new("delete_all doesn't support limit scope") if self.limit_value
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if conditions
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where(conditions).delete_all
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else
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stmt = Arel::DeleteManager.new(arel.engine)
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stmt.from(table)
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if joins_values.any?
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@klass.connection.join_to_delete(stmt, arel, table[primary_key])
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else
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stmt.wheres = arel.constraints
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end
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affected = @klass.connection.delete(stmt, 'SQL', bind_values)
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reset
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affected
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end
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end
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# Deletes the row with a primary key matching the +id+ argument, using a
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# SQL +DELETE+ statement, and returns the number of rows deleted. Active
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# Record objects are not instantiated, so the object's callbacks are not
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# executed, including any <tt>:dependent</tt> association options.
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#
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# You can delete multiple rows at once by passing an Array of <tt>id</tt>s.
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#
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# Note: Although it is often much faster than the alternative,
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# <tt>#destroy</tt>, skipping callbacks might bypass business logic in
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# your application that ensures referential integrity or performs other
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# essential jobs.
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#
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# ==== Examples
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#
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# # Delete a single row
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# Todo.delete(1)
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#
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# # Delete multiple rows
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# Todo.delete([2,3,4])
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def delete(id_or_array)
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where(primary_key => id_or_array).delete_all
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end
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# Causes the records to be loaded from the database if they have not
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# been loaded already. You can use this if for some reason you need
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# to explicitly load some records before actually using them. The
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# return value is the relation itself, not the records.
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#
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# Post.where(published: true).load # => #<ActiveRecord::Relation>
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def load
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exec_queries unless loaded?
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self
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end
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# Forces reloading of relation.
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def reload
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reset
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load
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end
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def reset
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@first = @last = @to_sql = @order_clause = @scope_for_create = @arel = @loaded = nil
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@should_eager_load = @join_dependency = nil
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@records = []
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self
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end
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# Returns sql statement for the relation.
|
|
#
|
|
# User.where(name: 'Oscar').to_sql
|
|
# # => SELECT "users".* FROM "users" WHERE "users"."name" = 'Oscar'
|
|
def to_sql
|
|
@to_sql ||= begin
|
|
relation = self
|
|
connection = klass.connection
|
|
visitor = connection.visitor
|
|
|
|
if eager_loading?
|
|
join_dependency = construct_join_dependency
|
|
relation = construct_relation_for_association_find(join_dependency)
|
|
end
|
|
|
|
ast = relation.arel.ast
|
|
binds = relation.bind_values.dup
|
|
visitor.accept(ast) do
|
|
connection.quote(*binds.shift.reverse)
|
|
end
|
|
end
|
|
end
|
|
|
|
# Returns a hash of where conditions.
|
|
#
|
|
# User.where(name: 'Oscar').where_values_hash
|
|
# # => {name: "Oscar"}
|
|
def where_values_hash
|
|
equalities = where_values.grep(Arel::Nodes::Equality).find_all { |node|
|
|
node.left.relation.name == table_name
|
|
}
|
|
|
|
binds = Hash[bind_values.find_all(&:first).map { |column, v| [column.name, v] }]
|
|
binds.merge!(Hash[bind_values.find_all(&:first).map { |column, v| [column.name, v] }])
|
|
|
|
Hash[equalities.map { |where|
|
|
name = where.left.name
|
|
[name, binds.fetch(name.to_s) { where.right }]
|
|
}]
|
|
end
|
|
|
|
def scope_for_create
|
|
@scope_for_create ||= where_values_hash.merge(create_with_value)
|
|
end
|
|
|
|
# Returns true if relation needs eager loading.
|
|
def eager_loading?
|
|
@should_eager_load ||=
|
|
eager_load_values.any? ||
|
|
includes_values.any? && (joined_includes_values.any? || references_eager_loaded_tables?)
|
|
end
|
|
|
|
# Joins that are also marked for preloading. In which case we should just eager load them.
|
|
# Note that this is a naive implementation because we could have strings and symbols which
|
|
# represent the same association, but that aren't matched by this. Also, we could have
|
|
# nested hashes which partially match, e.g. { a: :b } & { a: [:b, :c] }
|
|
def joined_includes_values
|
|
includes_values & joins_values
|
|
end
|
|
|
|
# +uniq+ and +uniq!+ are silently deprecated. +uniq_value+ delegates to +distinct_value+
|
|
# to maintain backwards compatibility. Use +distinct_value+ instead.
|
|
def uniq_value
|
|
distinct_value
|
|
end
|
|
|
|
# Compares two relations for equality.
|
|
def ==(other)
|
|
case other
|
|
when Relation
|
|
other.to_sql == to_sql
|
|
when Array
|
|
to_a == other
|
|
end
|
|
end
|
|
|
|
def pretty_print(q)
|
|
q.pp(self.to_a)
|
|
end
|
|
|
|
# Returns true if relation is blank.
|
|
def blank?
|
|
to_a.blank?
|
|
end
|
|
|
|
def values
|
|
Hash[@values]
|
|
end
|
|
|
|
def inspect
|
|
entries = to_a.take([limit_value, 11].compact.min).map!(&:inspect)
|
|
entries[10] = '...' if entries.size == 11
|
|
|
|
"#<#{self.class.name} [#{entries.join(', ')}]>"
|
|
end
|
|
|
|
private
|
|
|
|
def exec_queries
|
|
@records = eager_loading? ? find_with_associations : @klass.find_by_sql(arel, bind_values)
|
|
|
|
preload = preload_values
|
|
preload += includes_values unless eager_loading?
|
|
preload.each do |associations|
|
|
ActiveRecord::Associations::Preloader.new(@records, associations).run
|
|
end
|
|
|
|
@records.each { |record| record.readonly! } if readonly_value
|
|
|
|
@loaded = true
|
|
@records
|
|
end
|
|
|
|
def references_eager_loaded_tables?
|
|
joined_tables = arel.join_sources.map do |join|
|
|
unless join.is_a?(Arel::Nodes::StringJoin)
|
|
[join.left.table_name, join.left.table_alias]
|
|
end
|
|
end
|
|
|
|
joined_tables += [table.name, table.table_alias]
|
|
|
|
# always convert table names to downcase as in Oracle quoted table names are in uppercase
|
|
joined_tables = joined_tables.flatten.compact.map { |t| t.downcase }.uniq
|
|
|
|
(references_values - joined_tables).any?
|
|
end
|
|
end
|
|
end
|