498 lines
18 KiB
Ruby
498 lines
18 KiB
Ruby
module ActiveRecord
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# = Active Record Persistence
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module Persistence
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extend ActiveSupport::Concern
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module ClassMethods
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# Creates 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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# The +attributes+ parameter can be either a Hash or an Array of Hashes. These Hashes describe the
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# attributes on the objects that are to be created.
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#
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# +create+ respects mass-assignment security and accepts either +:as+ or +:without_protection+ options
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# in the +options+ parameter.
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#
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# ==== Examples
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# # Create a single new object
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# User.create(first_name: 'Jamie')
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#
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# # Create an Array of new objects
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# User.create([{ first_name: 'Jamie' }, { first_name: 'Jeremy' }])
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#
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# # Create a single object and pass it into a block to set other attributes.
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# User.create(first_name: 'Jamie') do |u|
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# u.is_admin = false
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# end
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#
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# # Creating an Array of new objects using a block, where the block is executed for each object:
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# User.create([{ first_name: 'Jamie' }, { first_name: 'Jeremy' }]) do |u|
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# u.is_admin = false
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# end
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def create(attributes = nil, &block)
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if attributes.is_a?(Array)
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attributes.collect { |attr| create(attr, &block) }
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else
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object = new(attributes, &block)
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object.save
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object
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end
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end
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# Given an attributes hash, +instantiate+ returns a new instance of
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# the appropriate class.
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#
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# For example, +Post.all+ may return Comments, Messages, and Emails
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# by storing the record's subclass in a +type+ attribute. By calling
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# +instantiate+ instead of +new+, finder methods ensure they get new
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# instances of the appropriate class for each record.
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#
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# See +ActiveRecord::Inheritance#discriminate_class_for_record+ to see
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# how this "single-table" inheritance mapping is implemented.
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def instantiate(record, column_types = {})
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klass = discriminate_class_for_record(record)
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column_types = klass.decorate_columns(column_types.dup)
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klass.allocate.init_with('attributes' => record, 'column_types' => column_types)
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end
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private
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# Called by +instantiate+ to decide which class to use for a new
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# record instance.
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#
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# See +ActiveRecord::Inheritance#discriminate_class_for_record+ for
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# the single-table inheritance discriminator.
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def discriminate_class_for_record(record)
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self
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end
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end
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# Returns true if this object hasn't been saved yet -- that is, a record
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# for the object doesn't exist in the data store yet; otherwise, returns false.
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def new_record?
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sync_with_transaction_state
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@new_record
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end
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# Returns true if this object has been destroyed, otherwise returns false.
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def destroyed?
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sync_with_transaction_state
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@destroyed
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end
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# Returns true if the record is persisted, i.e. it's not a new record and it was
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# not destroyed, otherwise returns false.
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def persisted?
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!(new_record? || destroyed?)
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end
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# Saves the model.
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#
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# If the model is new a record gets created in the database, otherwise
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# the existing record gets updated.
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#
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# By default, save always run validations. If any of them fail the action
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# is cancelled and +save+ returns +false+. However, if you supply
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# validate: false, validations are bypassed altogether. See
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# ActiveRecord::Validations for more information.
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#
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# There's a series of callbacks associated with +save+. If any of the
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# <tt>before_*</tt> callbacks return +false+ the action is cancelled and
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# +save+ returns +false+. See ActiveRecord::Callbacks for further
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# details.
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#
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# Attributes marked as readonly are silently ignored if the record is
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# being updated.
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def save(*)
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create_or_update
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rescue ActiveRecord::RecordInvalid
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false
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end
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# Saves the model.
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#
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# If the model is new a record gets created in the database, otherwise
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# the existing record gets updated.
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#
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# With <tt>save!</tt> validations always run. If any of them fail
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# ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations
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# for more information.
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#
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# There's a series of callbacks associated with <tt>save!</tt>. If any of
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# the <tt>before_*</tt> callbacks return +false+ the action is cancelled
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# and <tt>save!</tt> raises ActiveRecord::RecordNotSaved. See
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# ActiveRecord::Callbacks for further details.
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#
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# Attributes marked as readonly are silently ignored if the record is
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# being updated.
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def save!(*)
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create_or_update || raise(RecordNotSaved)
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end
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# Deletes the record in the database and freezes this instance to
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# reflect that no changes should be made (since they can't be
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# persisted). Returns the frozen instance.
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#
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# The row is simply removed with an SQL +DELETE+ statement on the
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# record's primary key, and no callbacks are executed.
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#
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# To enforce the object's +before_destroy+ and +after_destroy+
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# callbacks or any <tt>:dependent</tt> association
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# options, use <tt>#destroy</tt>.
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def delete
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self.class.delete(id) if persisted?
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@destroyed = true
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freeze
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end
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# Deletes the record in the database and freezes this instance to reflect
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# that no changes should be made (since they can't be persisted).
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#
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# There's a series of callbacks associated with <tt>destroy</tt>. If
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# the <tt>before_destroy</tt> callback return +false+ the action is cancelled
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# and <tt>destroy</tt> returns +false+. See
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# ActiveRecord::Callbacks for further details.
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def destroy
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raise ReadOnlyRecord if readonly?
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destroy_associations
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destroy_row if persisted?
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@destroyed = true
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freeze
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end
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# Deletes the record in the database and freezes this instance to reflect
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# that no changes should be made (since they can't be persisted).
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#
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# There's a series of callbacks associated with <tt>destroy!</tt>. If
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# the <tt>before_destroy</tt> callback return +false+ the action is cancelled
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# and <tt>destroy!</tt> raises ActiveRecord::RecordNotDestroyed. See
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# ActiveRecord::Callbacks for further details.
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def destroy!
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destroy || raise(ActiveRecord::RecordNotDestroyed)
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end
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# Returns an instance of the specified +klass+ with the attributes of the
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# current record. This is mostly useful in relation to single-table
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# inheritance structures where you want a subclass to appear as the
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# superclass. This can be used along with record identification in
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# Action Pack to allow, say, <tt>Client < Company</tt> to do something
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# like render <tt>partial: @client.becomes(Company)</tt> to render that
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# instance using the companies/company partial instead of clients/client.
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#
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# Note: The new instance will share a link to the same attributes as the original class.
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# So any change to the attributes in either instance will affect the other.
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def becomes(klass)
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became = klass.new
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became.instance_variable_set("@attributes", @attributes)
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became.instance_variable_set("@attributes_cache", @attributes_cache)
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became.instance_variable_set("@new_record", new_record?)
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became.instance_variable_set("@destroyed", destroyed?)
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became.instance_variable_set("@errors", errors)
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became
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end
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# Wrapper around +becomes+ that also changes the instance's sti column value.
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# This is especially useful if you want to persist the changed class in your
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# database.
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#
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# Note: The old instance's sti column value will be changed too, as both objects
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# share the same set of attributes.
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def becomes!(klass)
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became = becomes(klass)
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became.public_send("#{klass.inheritance_column}=", klass.sti_name) unless self.class.descends_from_active_record?
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became
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end
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# Updates a single attribute and saves the record.
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# This is especially useful for boolean flags on existing records. Also note that
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#
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# * Validation is skipped.
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# * Callbacks are invoked.
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# * updated_at/updated_on column is updated if that column is available.
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# * Updates all the attributes that are dirty in this object.
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#
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# This method raises an +ActiveRecord::ActiveRecordError+ if the
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# attribute is marked as readonly.
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def update_attribute(name, value)
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name = name.to_s
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verify_readonly_attribute(name)
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send("#{name}=", value)
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save(validate: false)
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end
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# Updates the attributes of the model from the passed-in hash and saves the
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# record, all wrapped in a transaction. If the object is invalid, the saving
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# will fail and false will be returned.
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def update(attributes)
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# The following transaction covers any possible database side-effects of the
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# attributes assignment. For example, setting the IDs of a child collection.
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with_transaction_returning_status do
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assign_attributes(attributes)
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save
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end
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end
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alias update_attributes update
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# Updates its receiver just like +update+ but calls <tt>save!</tt> instead
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# of +save+, so an exception is raised if the record is invalid.
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def update!(attributes)
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# The following transaction covers any possible database side-effects of the
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# attributes assignment. For example, setting the IDs of a child collection.
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with_transaction_returning_status do
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assign_attributes(attributes)
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save!
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end
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end
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alias update_attributes! update!
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# Equivalent to <code>update_columns(name => value)</code>.
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def update_column(name, value)
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update_columns(name => value)
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end
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# Updates the attributes directly in the database issuing an UPDATE SQL
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# statement and sets them in the receiver:
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#
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# user.update_columns(last_request_at: Time.current)
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#
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# This is the fastest way to update attributes because it goes straight to
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# the database, but take into account that in consequence the regular update
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# procedures are totally bypassed. In particular:
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#
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# * Validations are skipped.
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# * Callbacks are skipped.
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# * +updated_at+/+updated_on+ are not updated.
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#
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# This method raises an +ActiveRecord::ActiveRecordError+ when called on new
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# objects, or when at least one of the attributes is marked as readonly.
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def update_columns(attributes)
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raise ActiveRecordError, "can not update on a new record object" unless persisted?
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attributes.each_key do |key|
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verify_readonly_attribute(key.to_s)
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end
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updated_count = self.class.unscoped.where(self.class.primary_key => id).update_all(attributes)
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attributes.each do |k, v|
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raw_write_attribute(k, v)
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end
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updated_count == 1
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end
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# Initializes +attribute+ to zero if +nil+ and adds the value passed as +by+ (default is 1).
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# The increment is performed directly on the underlying attribute, no setter is invoked.
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# Only makes sense for number-based attributes. Returns +self+.
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def increment(attribute, by = 1)
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self[attribute] ||= 0
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self[attribute] += by
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self
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end
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# Wrapper around +increment+ that saves the record. This method differs from
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# its non-bang version in that it passes through the attribute setter.
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# Saving is not subjected to validation checks. Returns +true+ if the
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# record could be saved.
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def increment!(attribute, by = 1)
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increment(attribute, by).update_attribute(attribute, self[attribute])
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end
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# Initializes +attribute+ to zero if +nil+ and subtracts the value passed as +by+ (default is 1).
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# The decrement is performed directly on the underlying attribute, no setter is invoked.
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# Only makes sense for number-based attributes. Returns +self+.
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def decrement(attribute, by = 1)
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self[attribute] ||= 0
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self[attribute] -= by
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self
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end
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# Wrapper around +decrement+ that saves the record. This method differs from
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# its non-bang version in that it passes through the attribute setter.
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# Saving is not subjected to validation checks. Returns +true+ if the
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# record could be saved.
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def decrement!(attribute, by = 1)
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decrement(attribute, by).update_attribute(attribute, self[attribute])
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end
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# Assigns to +attribute+ the boolean opposite of <tt>attribute?</tt>. So
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# if the predicate returns +true+ the attribute will become +false+. This
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# method toggles directly the underlying value without calling any setter.
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# Returns +self+.
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def toggle(attribute)
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self[attribute] = !send("#{attribute}?")
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self
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end
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# Wrapper around +toggle+ that saves the record. This method differs from
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# its non-bang version in that it passes through the attribute setter.
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# Saving is not subjected to validation checks. Returns +true+ if the
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# record could be saved.
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def toggle!(attribute)
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toggle(attribute).update_attribute(attribute, self[attribute])
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end
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# Reloads the record from the database.
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#
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# This method modifies the receiver in-place. Attributes are updated, and
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# caches busted, in particular the associations cache.
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#
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# If the record no longer exists in the database <tt>ActiveRecord::RecordNotFound</tt>
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# is raised. Otherwise, in addition to the in-place modification the method
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# returns +self+ for convenience.
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#
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# The optional <tt>:lock</tt> flag option allows you to lock the reloaded record:
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#
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# reload(lock: true) # reload with pessimistic locking
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#
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# Reloading is commonly used in test suites to test something is actually
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# written to the database, or when some action modifies the corresponding
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# row in the database but not the object in memory:
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#
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# assert account.deposit!(25)
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# assert_equal 25, account.credit # check it is updated in memory
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# assert_equal 25, account.reload.credit # check it is also persisted
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#
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# Another commom use case is optimistic locking handling:
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#
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# def with_optimistic_retry
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# begin
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# yield
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# rescue ActiveRecord::StaleObjectError
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# begin
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# # Reload lock_version in particular.
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# reload
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# rescue ActiveRecord::RecordNotFound
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# # If the record is gone there is nothing to do.
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# else
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# retry
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# end
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# end
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# end
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#
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def reload(options = nil)
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clear_aggregation_cache
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clear_association_cache
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fresh_object =
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if options && options[:lock]
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self.class.unscoped { self.class.lock.find(id) }
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else
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self.class.unscoped { self.class.find(id) }
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end
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@attributes.update(fresh_object.instance_variable_get('@attributes'))
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@columns_hash = fresh_object.instance_variable_get('@columns_hash')
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@attributes_cache = {}
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self
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end
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# Saves the record with the updated_at/on attributes set to the current time.
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# Please note that no validation is performed and no callbacks are executed.
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# If an attribute name is passed, that attribute is updated along with
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# updated_at/on attributes.
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#
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# product.touch # updates updated_at/on
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# product.touch(:designed_at) # updates the designed_at attribute and updated_at/on
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#
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# If used along with +belongs_to+ then +touch+ will invoke +touch+ method on associated object.
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#
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# class Brake < ActiveRecord::Base
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# belongs_to :car, touch: true
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# end
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#
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# class Car < ActiveRecord::Base
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# belongs_to :corporation, touch: true
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# end
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#
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# # triggers @brake.car.touch and @brake.car.corporation.touch
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# @brake.touch
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#
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# Note that +touch+ must be used on a persisted object, or else an
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# ActiveRecordError will be thrown. For example:
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#
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# ball = Ball.new
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# ball.touch(:updated_at) # => raises ActiveRecordError
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#
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def touch(name = nil)
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raise ActiveRecordError, "can not touch on a new record object" unless persisted?
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attributes = timestamp_attributes_for_update_in_model
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attributes << name if name
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unless attributes.empty?
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current_time = current_time_from_proper_timezone
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changes = {}
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attributes.each do |column|
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column = column.to_s
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changes[column] = write_attribute(column, current_time)
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end
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changes[self.class.locking_column] = increment_lock if locking_enabled?
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@changed_attributes.except!(*changes.keys)
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primary_key = self.class.primary_key
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self.class.unscoped.where(primary_key => self[primary_key]).update_all(changes) == 1
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end
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end
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private
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# A hook to be overridden by association modules.
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def destroy_associations
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end
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def destroy_row
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relation_for_destroy.delete_all
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end
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def relation_for_destroy
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pk = self.class.primary_key
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column = self.class.columns_hash[pk]
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substitute = self.class.connection.substitute_at(column, 0)
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relation = self.class.unscoped.where(
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self.class.arel_table[pk].eq(substitute))
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relation.bind_values = [[column, id]]
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relation
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end
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def create_or_update
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raise ReadOnlyRecord if readonly?
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result = new_record? ? create_record : update_record
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result != false
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end
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# Updates the associated record with values matching those of the instance attributes.
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# Returns the number of affected rows.
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def update_record(attribute_names = @attributes.keys)
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attributes_values = arel_attributes_with_values_for_update(attribute_names)
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if attributes_values.empty?
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0
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else
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self.class.unscoped.update_record attributes_values, id, id_was
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end
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end
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# Creates a record with values matching those of the instance attributes
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# and returns its id.
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def create_record(attribute_names = @attributes.keys)
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attributes_values = arel_attributes_with_values_for_create(attribute_names)
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new_id = self.class.unscoped.insert attributes_values
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self.id ||= new_id if self.class.primary_key
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@new_record = false
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id
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end
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def verify_readonly_attribute(name)
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raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
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end
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end
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end
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