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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.

Ecto 2.0 requires Elixir 1.2+.

Highlights

Revamped changesets

Due to feedback, we have made three important changes to changesets:

  1. changeset.model has been renamed to changeset.data (we no longer have "models" in Ecto)
  2. Passing required and optional fields to cast/4 is deprecated in favor of cast/3 and validate_required/3
  3. The :empty atom in cast(source, :empty, required, optional) has been deprecated, please use an empty map or :invalid instead

To summarize those changes, instead of:

def changeset(user, params \\ :empty) do
  user
  |> cast(params, [:name], [:age])
end

One should write:

def changeset(user, params \\ %{}) do
  user
  |> cast(params, [:name, :age])
  |> validate_required([:name])
end

Subqueries

Ecto v2.0 introduces Ecto.Query.subquery/1 that will convert any query into a subquery to be used either as part of a from or a join. For example, if you want to calculate the average number of visits per posts, you can write:

query = from p in Post, select: avg(p.visits)
TestRepo.all(query) #=> [#Decimal<1743>]

However, if you want to calculate the average only across the top 10 most visited, you need subqueries:

query = from p in Post, select: [:visits], order_by: [desc: :visits], limit: 10
TestRepo.all(from p in subquery(query), select: avg(p.visits)) #=> [#Decimal<4682>]

Or alternatively, for the particular example where you are calculating aggregates, use the new Repo.aggregate function that handles those concerns automatically for you:

# Average across all
TestRepo.aggregate(Post, :avg, :visits) #=> #Decimal<1743>

# Average across top 10
query = from Post, order_by: [desc: :visits], limit: 10
TestRepo.aggregate(query, :avg, :visits) #=> #Decimal<4682>

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 in order to disable the automatic checkout of connections:

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!

Application Repo Configuration

Ecto now requires you to explicitly configure your repo's in your top level config. You can avoid this warning by passing the -r flag or by setting the repositories managed by this application in your config/config.exs:

config :my_app, ecto_repos: [...]

The configuration may be an empty list if it does not define any repo.

v2.0.2 (2016-06-27)

Bug fixes

  • [Ecto.Time] Add minute, second and microsecond handling to Ecto.Time
  • [Ecto.Adapters.SQL.Sandbox] Fix disconnections inside the sandbox

v2.0.1 (2016-06-21)

Bug fixes

  • [Postgres] Ensures the :postgrex application is restarted after running migrations

v2.0.0 (2016-06-21)

Backwards incompatible changes

  • [Changeset] changeset.model has been renamed to changeset.data
  • [Changeset] changeset.optional has been removed
  • [Changeset] changeset.errors now always returns tuple {String.t, Keyword.t} in its values
  • [DateTime] The "Z" (UTC) at the end of an ISO 8601 time has been removed as UTC should not be assumed
  • [LogEntry] Overhaul log entry and store times in :native units
  • [Repo] Ecto.StaleModelError has been renamed to Ecto.StaleEntryError
  • [Repo] Poolboy now expects :pool_overflow option instead of :max_overflow (keep in mind though using such option is discourage altogether as it establishes short-lived connections to the database, likely being worse to performance in both short- and long-term)
  • [Repo] 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)
  • [Repo] Ecto.Pools.Poolboy and Ecto.Pools.SojournBroker have been removed in favor of DBConnection.Poolboy and DBConnection.Sojourn
  • [Repo] :timeout in Repo.transaction now affects the whole transaction block and not only the particular transaction queries
  • [Repo] Overriding Repo.log/1 is no longer supported. Instead provide custom loggers configuration via :loggers. The default is: [Ecto.LogEntry]
  • [Schema] Array fields no longer default to an empty list []. Previous behaviour can be achieved by passing default: [] to the field definition
  • [Schema] __schema__(:types) now returns map
  • [SQL] 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
  • [UUID] Ecto.UUID.dump/1 now returns {:ok, binary}

Soft deprecations (no warnings emitted)

  • [Changeset] Deprecate Ecto.Changeset.cast/4 in favor of Ecto.Changeset.cast/3 + Ecto.Changeset.validate_required/3

Deprecations

  • [Changeset] Deprecate :empty in Ecto.Changeset.cast
  • [Repo] Repo.after_connect/1 is deprecated, please pass the :after_connect repository option instead

Enhancements

  • [Adapter] Ensure adapters work on native types, guaranteeing adapters compose better with custom types
  • [Adapter] Support prepared queries in adapters
  • [Adapter] Add support for loading and dumping structures
  • [Changeset] Include the type that failed to cast in changeset errors. Example: [profile: {"is invalid", [type: :map]}]
  • [DateTime] Ensure the given date and datetimes are valid
  • [Migration] Add support for partial indexes by specifying the :where option when on Ecto.Migration.index/2
  • [Migration] Allow the migration table name to be configured in the repository via :migration_source
  • [Migration] Support :on_update for Ecto.Migrate.references
  • [Migration] Use pool of 1 connection for mix ecto.migrate/rollback
  • [Mix] Automatically reenable migration and repository management tasks after execution
  • [Preloader] Support mixing preloads and assocs
  • [Postgres] Add migration and changeset support for PostgreSQL exclusion constraints. Example: create constraint(:sizes, :cannot_overlap, exclude: ~s|gist (int4range("min", "max", '[]') WITH &&)|) and exclusion_constraint(changeset, :sizes, name: :cannot_overlap, message: "must not overlap")
  • [Postgres] Support lateral joins (via fragments)
  • [Postgres] Add migration and changeset support for PostgreSQL check constraints. Example: create constraint(:products, "positive_price", check: "price > 0") and check_constraint(changeset, :price, name: :positive_price, message: "must be greater than zero")
  • [Query] Allow the :on field to be specified with association joins
  • [Query] Support expressions in map keys in select in queries. Example: from p in Post, select: %{p.title => p.visitors}
  • [Query] Support map update syntax. Example: from p in Post, select: %{p | title: "fixed"}
  • [Query] Allow struct fields to be selected with struct/2 and map fields with map/2, including support for dynamic fields
  • [Query] Add first/2 and last/2
  • [Repo] Add Repo.aggregate/4 for easy aggregations
  • [Repo] Allow custom select field in preload queries
  • [Repo] Support the :force option in preloads
  • [Repo] Perform preloads in parallel by default
  • [Repo] Add Repo.in_transaction? to know if the current process is in a transaction
  • [Repo] Support :returning option in insert_all, update_all and delete_all
  • [Schema] Allow @schema_prefix to be configured per schema. It is used for new structs as well as queries where the given schema is used as from
  • [Schema] Support MFA on autogenerate
  • [Schema] Support composite primary keys
  • [Type] Add type {:map, inner_type}

Bug fixes

  • [Changeset] The :required option on cast_assoc and cast_embed will now tag has_many and embeds_many relationships as missing if they contain an empty list
  • [DateTime] Fix Date/DateTime serialization for years above 9999
  • [Postgres] Switch pg storage management away from psql and use direct database connections, solving many issues like locale and database connection
  • [Repo] Ensure nested preload works even if intermediate associations were already loaded
  • [Repo] Do not attempt to execute insert/update/delete statement for associations if a previous operation failed due to a constraint error
  • [Schema] Ensure inserted_at autogeneration runs before updated_at autogeneration

Previous versions

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