Ecto.Adapters.SQL
Behaviour and implementation for SQL adapters.
The implementation for SQL adapter provides a pooled based implementation of SQL and also expose a query function to developers.
Developers that use Ecto.Adapters.SQL
should implement
the connection module with specifics on how to connect
to the database and also how to translate the queries
to SQL. See Ecto.Adapters.SQL.Connection
for more info.
Summary↑
begin_test_transaction(repo, opts \\ []) | Starts a transaction for test |
query(repo, sql, params, opts \\ []) | Runs custom SQL query on given repo |
restart_test_transaction(repo, opts \\ []) | Restarts a test transaction, see |
rollback_test_transaction(repo, opts \\ []) | Ends a test transaction, see |
Functions
Specs:
- begin_test_transaction(Ecto.Repo.t, Keyword.t) :: :ok
Starts a transaction for test.
This function work by starting a transaction and storing the connection
back in the pool with an open transaction. At the end of the test, the
transaction must be rolled back with rollback_test_transaction
,
reverting all data added during tests.
IMPORTANT: Test transactions only work if the connection pool has size of 1 and does not support any overflow.
Example
The first step is to configure your database pool to have size of
1 and no max overflow. You set those options in your config/config.exs
:
config :my_app, Repo,
size: 1,
max_overflow: 0
Since you don't want those options in your production database, we
typically recommend to create a config/test.exs
and add the
following to the bottom of your config/config.exs
file:
import_config "config/#{Mix.env}.exs"
Now with the test database properly configured, you can write transactional tests:
# At the end of your test_helper.exs
# From now, all tests happen inside a transaction
Ecto.Adapters.SQL.begin_test_transaction(TestRepo)
defmodule PostTest do
# Tests that use the shared repository cannot be async
use ExUnit.Case
setup do
# Go back to a clean slate at the beginning of every test
Ecto.Adapters.SQL.restart_test_transaction(TestRepo)
:ok
end
test "create comment" do
assert %Post{} = TestRepo.insert(%Post{})
end
end
In some cases, you may want to start the test transaction only for specific tests and then roll it back. You can do it as:
defmodule PostTest do
# Tests that use the shared repository cannot be async
use ExUnit.Case
setup_all do
# Wrap this case in a transaction
Ecto.Adapters.SQL.begin_test_transaction(TestRepo)
# Roll it back once we are done
on_exit fn ->
Ecto.Adapters.SQL.rollback_test_transaction(TestRepo)
end
:ok
end
setup do
# Go back to a clean slate at the beginning of every test
Ecto.Adapters.SQL.restart_test_transaction(TestRepo)
:ok
end
test "create comment" do
assert %Post{} = TestRepo.insert(%Post{})
end
end
Specs:
- query(Ecto.Repo.t, String.t, [term], Keyword.t) :: %{rows: nil | [tuple], num_rows: non_neg_integer} | no_return
Runs custom SQL query on given repo.
In case of success, it must return an :ok
tuple containing
a map with at least two keys:
:num_rows
- the number of rows affected:rows
- the result set as a list.nil
may be returned instead of the list if the command does not yield any row as result (but still yields the number of affected rows, like adelete
command without returning would)
Options
:timeout
- The time in milliseconds to wait for the call to finish,:infinity
will wait indefinitely (default: 5000):log
- When false, does not log the query
Examples
iex> Ecto.Adapters.SQL.query(MyRepo, "SELECT $1 + $2", [40, 2])
%{rows: [{42}], num_rows: 1}
Specs:
- restart_test_transaction(Ecto.Repo.t, Keyword.t) :: :ok
Restarts a test transaction, see begin_test_transaction/2
.
Specs:
- rollback_test_transaction(Ecto.Repo.t, Keyword.t) :: :ok
Ends a test transaction, see begin_test_transaction/2
.