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CHANGELOG.md

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Changelog for v2.0

This is a new major release of Ecto that removes previously deprecated features and introduces a series of improvements and features based on db_connection.

Highlights

Concurrent transactional tests

Ecto has reimplemented the Ecto.Adapters.SQL.Sandbox pool used for testing to use an ownership mechanism. This allows tests to safely run concurrently even when depending on the database. To use, declare sandbox as your pool in your repository configuration, as before:

pool: Ecto.Adapters.SQL.Sandbox

Now at the end of your test_helper.exs, set the sandbox mode to :manual, forcing connections to be automatically checked out:

Ecto.Adapters.SQL.Sandbox.mode(TestRepo, :manual)

And now checkout the connection in the setup block of every test case that needs the database:

setup do
  :ok = Ecto.Adapters.SQL.Sandbox.checkout(TestRepo)
end

The previous sandbox API, which used begin_test_transaction and restart_test_transaction, is no longer supported.

Insert all

Ecto now allows developers to insert multiple entries at once via Ecto.Repo.insert_all/3:

Ecto.Repo.insert_all Post, [%{title: "foo"}, %{title: "bar"}]

Similar to update_all/3, insert_all/3 is meant to be closer to the datastore and it won't automatically handle autogenerated fields like inserted_at or updated_at timestamps. insert_all/3 also adds to Ecto the ability to introduce entries to the database without an underlying Ecto.Schema by simply giving a table name:

Ecto.Repo.insert_all "some_table", [%{hello: "foo"}, %{hello: "bar"}]

Many to many

Ecto 2.0 supports many_to_many associations:

defmodule Post do
  use Ecto.Schema
  schema "posts" do
    many_to_many :tags, Tag, join_through: "posts_tags"
  end
end

The join_through option can be a string, representing a table that will have both post_id and tag_id columns, or a regular schema, like PostTag, which would also handle primary keys and autogenerate fields. This is an improvement over has_many :through as has_many :through relationships are read-only, while many_to_many supports also inserting, updating and deleting associated entries through changeset, as we will see next.

Improved association support

Ecto now supports belongs_to and many_to_many associations to be cast or changed via changesets, beyond has_one, has_many and embeds. Not only that, Ecto supports associations and embeds to be defined directly from the struct on insertion. For example, one can call:

Repo.insert! %Permalink{
  url: "//root",
  post: %Post{
    title: "A permalink belongs to a post which we are inserting",
    comments: [
      %Comment{text: "child 1"},
      %Comment{text: "child 2"},
    ]
  }
}

This allows developers to easily insert a tree of structs into the database, be it when seeding data for production or during tests.

Finally, Ecto now allows putting existing records in changesets, and the proper changes will be reflected in both structs and the database. For example, you may retrieve the permalink above and associate it to another existing post:

permalink
|> Ecto.Changeset.change
|> Ecto.Changeset.put_assoc(:post, existing_post)
|> Repo.update!

Backwards incompatible changes

  • Ecto.StaleModelError has been renamed to Ecto.StaleEntryError
  • Array fields no longer default to an empty list []. Previous behaviour can be achieved by passing default: [] to the field definition
  • Poolboy now expects :pool_overflow option instead of :max_overflow
  • Repo.insert/2 will now send only non-nil fields from the struct to the storage (in previous versions, all fields from the struct were sent to the database)
  • Ecto.Pools.Poolboy and Ecto.Pools.SojournBroker have been removed in favor of DBConnection.Poolboy and DBConnection.Sojourn
  • :timeout in Repo.transaction now affects the whole transaction block and not only the particular transaction queries
  • Ecto.Adapters.SQL.begin_test_transaction, Ecto.Adapters.SQL.restart_test_transaction and Ecto.Adapters.SQL.rollback_test_transaction have been removed in favor of the new ownership based Ecto.Adapters.SQL.Sandbox

Enhancements

  • Support expressions in map keys in select in queries. Example: from p in Post, select: %{p.title => p.visitors}
  • Add support for partial indexes by specifying the :where option when on Ecto.Migration.index/2
  • Allow dynamic and atom fields to be specified on group_by and distinct
  • Ensure adapters work on native types, guaranteeing adapters compose better with custom types
  • Allow the migration table name to be configured
  • Add migration support for PostgreSQL exclusion constraints. Example: create constraint(:sizes, :cannot_overlap, exclude: ~s|gist (int4range("min", "max", '[]') WITH &&)|)
  • Add migration and changeset support for PostgreSQL check constraints. Example: create constraint(@table.name, "positive_price", check: "price > 0") and check_constraint(changeset, :description, name: :positive_price, message: "must be greater than zero")

Bug fixes

  • The :required option on cast_assocand cast_embed will now tag has_many and embeds_many relationships as missing if they contain an empty list

Previous versions

  • See the CHANGELOG.md in the v1.1 branch