create db

README.md

@@ -40,7 +40,7 @@ In your app supervisor, start `Postgrex` and then the `ExqlMigration.Task`.
 
   children = [
     {Postgrex, postgres_conf},
-    {ExqlMigration.Supervisor, [
+    {ExqlMigration.Migration, [
         db_conn: postgres_conn,
         migrations_dir: migrations_dir,
         timeout: 5_000,      # default :infinity
@@ -57,13 +57,14 @@ if you have multiple DBs to setup:
 ```elixir
     children = [
       Supervisor.child_spec({Postgrex, db_A_conf}, id: :postgrex_A),
-      Supervisor.child_spec({ExqlMigration.Supervisor, [db_conn: db_A_conn, migrations_dir: db_A_migrations_dir]}, id: :exql_db_A),
+      Supervisor.child_spec({ExqlMigration.Migration, [db_conn: db_A_conn, migrations_dir: db_A_migrations_dir]}, id: :exql_db_A),
       Supervisor.child_spec({Postgrex, db_B_conf}, id: :postgrex_B),
-      Supervisor.child_spec({ExqlMigration.Supervisor, [db_conn: db_B_conn, migrations_dir: db_B_migrations_dir]}, id: :exql_db_B)
+      Supervisor.child_spec({ExqlMigration.Migration, [db_conn: db_B_conn, migrations_dir: db_B_migrations_dir]}, id: :exql_db_B)
     ]
 ```
 
-Check the sample app under `./sample_app`.
+`ExqlMigration.CreateDB` can be included in the supervision tree to create (if not exists) a database.
+Check the sample app under `./sample_app` for more details.
 
 # Development
 

lib/exql_migration.ex

@@ -4,6 +4,23 @@ defmodule ExqlMigration do
   require Logger
   alias ExqlMigration.{Log, Schema}
 
+  @spec create_db(Postgrex.conn(), String.t()) :: :ok
+  def create_db(conn, name) do
+    case Postgrex.query(conn, "create database #{name}", []) do
+      {:ok, _} ->
+        Logger.info("Create DB #{inspect(name)}")
+        :ok
+
+      {:error, %Postgrex.Error{postgres: %{code: :duplicate_database}}} ->
+        :ok
+
+      error ->
+        # coveralls-ignore-start
+        raise "#{inspect(error)}"
+        # coveralls-ignore-end
+    end
+  end
+
   @spec migrate(Postgrex.conn(), Path.t(), timeout(), boolean()) :: :ok
   def migrate(conn, migrations_dir, timeout, transactional) do
     Schema.setup(conn)

lib/exql_migration/create_db.ex

@@ -0,0 +1,36 @@
+# coveralls-ignore-start
+
+defmodule ExqlMigration.CreateDB do
+  @moduledoc "Migration runner Supervisor"
+
+  use Supervisor
+
+  require Logger
+
+  @type opts :: [{:db_conn, Postgrex.conn()} | {:db_name, String.t()}]
+
+  @spec start_link(opts()) :: Supervisor.on_start()
+  def start_link(opts) do
+    db_conn = Keyword.fetch!(opts, :db_conn)
+    db_name = Keyword.fetch!(opts, :db_name)
+
+    Supervisor.start_link(__MODULE__, {db_conn, db_name})
+  end
+
+  @impl Supervisor
+  @spec init({Postgrex.conn(), String.t()}) :: :ignore
+  def init({db_conn, db_name}) do
+    ExqlMigration.create_db(db_conn, db_name)
+
+    :ignore
+  rescue
+    exc ->
+      Logger.emergency("Create DB failed")
+      Logger.emergency(Exception.message(exc))
+      Logger.emergency("#{inspect(exc)}")
+
+      :init.stop()
+  end
+end
+
+# coveralls-ignore-stop

lib/exql_migration/task.ex → lib/exql_migration/migration.ex

@@ -1,6 +1,6 @@
 # coveralls-ignore-start
 
-defmodule ExqlMigration.Supervisor do
+defmodule ExqlMigration.Migration do
   @moduledoc "Migration runner Supervisor"
 
   use Supervisor

sample_app/config/config.exs

@@ -0,0 +1,7 @@
+import Config
+
+config :example, :db_postgres, name: :db_postgres
+
+config :example, :db_mydb,
+  name: :db_mydb,
+  migration_dir: "priv/migrations/mydb"

sample_app/config/runtime.exs

@@ -1,12 +1,15 @@
 import Config
 
-config :postgrex,
-  name: :db,
+config :example, :db_postgres,
   hostname: "localhost",
   username: "postgres",
   password: "postgres",
   database: "postgres",
-  pool_size: 5
+  pool_size: 1
 
-config :exql_migration,
-  migration_dir: "priv/migrations"
+config :example, :db_mydb,
+  hostname: "localhost",
+  username: "postgres",
+  password: "postgres",
+  database: "mydb",
+  pool_size: 5

sample_app/lib/example.ex

@@ -2,13 +2,18 @@ defmodule Example do
   use Application
 
   def start(_type, _args) do
-    postgrex_conf = Application.get_all_env(:postgrex)
-    db_conn = Application.fetch_env!(:postgrex, :name)
-    migrations_dir = Application.fetch_env!(:exql_migration, :migration_dir)
+    db_postgres_conf = Application.fetch_env!(:example, :db_postgres)
+    db_mydb_conf = Application.fetch_env!(:example, :db_mydb)
 
     children = [
-      {Postgrex, postgrex_conf},
-      {ExqlMigration.Supervisor, [db_conn: db_conn, migrations_dir: migrations_dir]}
+      # database "postgres" connection
+      Supervisor.child_spec({Postgrex, db_postgres_conf}, id: :db_postgres),
+      # create "mydb", connecting to "postgres" database
+      {ExqlMigration.CreateDB, [db_conn: db_postgres_conf[:name], db_name: db_mydb_conf[:database]]},
+      # database "mydb" connection
+      Supervisor.child_spec({Postgrex, db_mydb_conf}, id: :db_mydb),
+      # database "mydb" schema migrations
+      {ExqlMigration.Migration, [db_conn: db_mydb_conf[:name], migrations_dir: db_mydb_conf[:migration_dir]]}
     ]
 
     opts = [strategy: :one_for_one]

sample_app/priv/migrations/mydb/001.sql

@@ -0,0 +1 @@
+perform 1;

test/exql_migration_test.exs

@@ -19,8 +19,8 @@ defmodule ExqlMigrationTest do
 
   setup do
     on_exit(fn ->
-      Postgrex.query!(@postgrex_conn, "DROP SCHEMA IF EXISTS exql_migration CASCADE", [])
-      Postgrex.query!(@postgrex_conn, "DROP SCHEMA IF EXISTS test CASCADE", [])
+      Postgrex.query!(@postgrex_conn, "drop schema if exists exql_migration cascade", [])
+      Postgrex.query!(@postgrex_conn, "drop schema if exists test cascade", [])
     end)
 
     :ok
@@ -54,4 +54,16 @@ defmodule ExqlMigrationTest do
     ExqlMigration.migrate(@postgrex_conn, "test/all_migrations", @timeout, true)
     assert ^all = ExqlMigration.Log.migrations(@postgrex_conn)
   end
+
+  test "create DB" do
+    on_exit(fn ->
+      Postgrex.query!(@postgrex_conn, "drop database test_db", [])
+    end)
+
+    ExqlMigration.create_db(@postgrex_conn, "test_db")
+    ExqlMigration.create_db(@postgrex_conn, "test_db")
+
+    res = Postgrex.query!(@postgrex_conn, "select true from pg_database where datname = $1", ["test_db"])
+    assert %Postgrex.Result{num_rows: 1} = res
+  end
 end