Ector::Multi

Ector::Multi is an object for grouping multiple DB operations that should be performed in a single database transaction.

I literally copy the API and idea from Ecto::Multi, so I'm gonna copy the documentation as well.

Dependencies

At this moment, Ector::Multi requires ActiveRecord as a dependency and relies on it for CRUD operations and transactions. Eventually, I would like to be ORM-agnostic and be able to configure different ORMs and remove the hard dependency.

Getting started

Ector::Multi is an object for grouping multiple database operations.

Ector::Multi makes it possible to pack operations that should be performed in a single database transaction and gives a way to introspect the queued operations without actually performing them. Each operation is given a name that is unique and will identify its result in case of success or failure.

All operations will be executed in the order they were added.

The Ector::Multi object should be considered opaque. You can use common ruby techniques to dig into it, but accessing fields or directly modifying them is not advised.

Run

Ector::Multi allows you to run arbitrary functions as part of your transaction via run. This is especially useful when an operation depends on the value of a previous operation. For this reason, the function given as a callback to run will receive all changes performed by the multi so far.

The function given to run must return something or raise a Ector::Multi::OperationFailure. Raising an error will abort any further operations and make the whole multi fail.

Example

Let’s look at an example definition and usage. The use case we’ll be looking into is resetting a password. We need to update the account with proper information, log the request and remove all current sessions:

module PasswordManager
  def self.reset(account, params)
    Ector::Multi.new
    .update(:account, account, params)
    .create(:log, Log, account_id: account.id, changed_at: Time.now)
    .destroy_all(:clear_sessions, Session.where(account_id: account.id))
  end
end

We can later execute it in the integration layer using #commit:

  result = PasswordManager.reset(account, params).commit

The resulting object, a Ector::Multi::Result, will tell you if it succeeded or failed. Also, it is possible to dig into the results of each operation.

Functions

multi.append(second_mutli)

Appends the second multi to the first one

multi.destroy(name, instance)

Adds a destroy operation to the multi

multi.delete_all(name, queryable)

Adds a destroy_all operation to the multi

multi.error(name, value)

Causes the multi to fail with the given value

multi.create(name, model, attributes, &block = nil)

Adds a create operation to the multi

Ector::Multi.new

Returns an empty Ector::Multi object

multi.prepend(second_multi)

Prepends the second multi to the first one

multi.run(name, &run)

Adds a function to run as part of the multi

multi.to_list

Returns the list of operations stored in multi

multi.update(name, instance, updates, &block = nil)

Adds an update operation to the multi

multi.update_all(name, queryable, updates, &block = nil)

Adds an update_all operation to the multi