[#63] Migrations schema creation. Migrate function.

.gitignore

@@ -6,4 +6,5 @@ examples/blog/log
 *.o
 *.beam
 *.plt
-.rebar
+.rebar
+*.dump

Makefile

@@ -7,9 +7,9 @@ HOST?=$(shell hostname)
 NODE?=${NAME}@${HOST}
 DIALYZER_OUT?=${NAME}.plt
 
-ERL_ARGS?=-pa ebin -pa deps/*/ebin -name ${NODE}
+ERL_ARGS?=-pa ebin -pa deps/*/ebin -name ${NODE} -s sync
 
-all: getdeps compile edoc
+all: getdeps compile
 	${REBAR} compile
 
 blog:

rebar.config

@@ -23,7 +23,8 @@
   {emysql,      "0.*", {git, "[email protected]:Eonblast/Emysql.git",        "master"}},
   {emongo,      ".*",  {git, "[email protected]:marcelog/emongo.git", "marcelog_login_for_2_2_and_higher"}},
   {'sqlite3',   ".*",  {git, "[email protected]:alexeyr/erlang-sqlite3.git", "HEAD"}},
-  {worker_pool, ".*",  {git, "[email protected]:inaka/worker_pool.git",      "master"}}
+  {worker_pool, ".*",  {git, "[email protected]:inaka/worker_pool.git",      "master"}},
+  {sync,        ".*",  {git, "[email protected]:rustyio/sync.git",           "master"}}
 ]}.
 {xref_warnings, true}.
 {xref_checks, [undefined_function_calls, undefined_functions, locals_not_used, deprecated_function_calls, deprecated_functions]}.

src/sumo.erl

@@ -36,6 +36,9 @@
 -export([find/2, find_all/1, find_all/4, find_by/2, find_by/4, find_one/2]).
 -export([call/2, call/3]).
 
+%%% API for migrations.
+-export([migrate/0, rollback/0]).
+
 -type schema_name() :: atom().
 
 -type field_attr()  :: id|unique|index|not_null|auto_increment|{length, integer()}.
@@ -243,3 +246,15 @@ new_field(Name, Type, Attributes) ->
 -spec new_field(field_name(), field_type()) -> field().
 new_field(Name, Type) ->
   new_field(Name, Type, []).
+
+%% @doc Runs all migrations to get the DB up to date.
+-spec migrate() -> ok | {error, term()}.
+migrate() ->
+    sumo_migration:migrate(),
+    halt(0).
+
+%% @doc Rolls back the last migration and downgrades the DB version.
+-spec rollback() -> ok | {error, term()}.
+rollback() ->
+    sumo_migration:rollback(),
+    halt(0).

src/sumo_migration.erl

@@ -0,0 +1,85 @@
+-module(sumo_migration).
+
+-behavior(sumo_doc).
+
+-export([migrate/0, rollback/0]).
+
+-export([migration_update_list/1]).
+
+%%% sumo_db callbacks
+-export([sumo_schema/0, sumo_wakeup/1, sumo_sleep/1]).
+
+-callback up() -> string().
+-callback down() -> string().
+
+-type migration() :: atom().
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Exported
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-spec migrate() -> ok.
+migrate() ->
+    ensure_sumo_migration_doc(),
+    LastMigration = last_migration_update(),
+    Migrations = migration_update_list(LastMigration),
+    lists:foreach(fun(M) -> M:up() end, Migrations).
+
+-spec rollback() -> ok.
+rollback() ->
+    ensure_sumo_migration_doc(),
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% sumo_doc callbacks
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-spec sumo_schema() -> sumo:schema().
+sumo_schema() ->
+    Fields = [sumo:new_field(version, string)],
+    sumo:new_schema(?MODULE, Fields).
+
+-spec sumo_sleep(migration()) -> sumo:doc().
+sumo_sleep(Migration) ->
+    [{version, Migration}].
+
+-spec sumo_wakeup(sumo:doc()) -> migration().
+sumo_wakeup(Migration) ->
+    VersionBin = proplists:get_value(version, Migration),
+    binary_to_atom(VersionBin, utf8).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Internal
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%% @doc Make sure the schema_version table is present in the datastore.
+-spec ensure_sumo_migration_doc() -> ok.
+ensure_sumo_migration_doc() ->
+    sumo:create_schema(?MODULE).
+
+-spec last_migration_update() -> migration().
+last_migration_update() ->
+    Migrations = sumo:find_all(?MODULE),
+    lists:max(Migrations).
+
+-spec migration_update_list(migration()) -> [migration()].
+migration_update_list(LastMigration) ->
+    MigrationsDir = migrations_dir(),
+    Files = filelib:wildcard("*.erl", MigrationsDir),
+    F = compose([fun filename:rootname/1, fun list_to_atom/1]),
+    AvailableMigrations = lists:map(F, Files),
+    lists:filter(fun(X) -> X > LastMigration end, AvailableMigrations).
+
+-spec migrations_dir() -> string().
+migrations_dir() ->
+    case application:get_env(migrations_dir, sumo_db) of
+        undefined -> "src/migrations";
+        Dir -> Dir
+    end.
+
+-spec compose([fun()]) -> fun().
+compose(Funs) ->
+    Compose = fun(F, X) -> F(X) end,
+    fun(X) ->
+            lists:foldl(Compose, X, Funs)
+    end.

test/migrations/20140901_mig1.erl

@@ -0,0 +1,13 @@
+-module('20140901_mig1').
+
+-behavior(sumo_migration).
+
+-export([up/0, down/0]).
+
+up() ->
+    io:format("=== ~p up/0~n", [?MODULE]),
+    ok.
+
+down() ->
+    io:format("=== ~p down/0~n", [?MODULE]),
+    ok.

test/migrations/20140902_mig.erl

@@ -0,0 +1,13 @@
+-module('20140902_mig').
+
+-behavior(sumo_migration).
+
+-export([up/0, down/0]).
+
+up() ->
+    io:format("=== ~p up/0~n", [?MODULE]),
+    ok.
+
+down() ->
+    io:format("=== ~p down/0~n", [?MODULE]),
+    ok.

test/migrations/20140903_mig.erl

@@ -0,0 +1,13 @@
+-module('20140903_mig').
+
+-behavior(sumo_migration).
+
+-export([up/0, down/0]).
+
+up() ->
+    io:format("=== ~p up/0~n", [?MODULE]),
+    ok.
+
+down() ->
+    io:format("=== ~p down/0~n", [?MODULE]),
+    ok.