DB Migrations

Replacing modl’s built-in table creation and removal
with manual migrations. Thanks to @DavidHuie for
gomigrate!

cmd/bactdb/bactdb.go

@@ -117,8 +117,10 @@ The options are:
 	}
 
 	datastore.Connect()
+	migrationsPath := "./datastore/migrations"
+
 	if *drop {
-		datastore.Drop()
+		datastore.Drop(migrationsPath)
 	}
-	datastore.Create()
+	datastore.Create(migrationsPath)
 }

datastore/db.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"sync"
 
+	"github.com/DavidHuie/gomigrate"
 	"github.com/jmoiron/modl"
 	"github.com/jmoiron/sqlx"
 	_ "github.com/lib/pq"
@@ -37,21 +38,32 @@ func Connect() {
 var createSQL []string
 
 // Create the database schema. It calls log.Fatal if it encounters an error.
-func Create() {
-	if err := DB.CreateTablesIfNotExists(); err != nil {
-		log.Fatal("Error creating tables: ", err)
+func Create(path string) {
+	migrator, err := gomigrate.NewMigrator(DB.Dbx.DB, gomigrate.Postgres{}, path)
+	if err != nil {
+		log.Fatal("Error initializing migrations: ", err)
 	}
-	for _, query := range createSQL {
-		if _, err := DB.Exec(query); err != nil {
-			log.Fatalf("Error running query %q: %s", query, err)
-		}
+
+	pwd, err := os.Getwd()
+	log.Print("current path: ", pwd)
+
+	err = migrator.Migrate()
+	if err != nil {
+		log.Fatal("Error applying migrations: ", err)
 	}
 }
 
 // Drop the database schema
-func Drop() {
-	// TODO(mrd): raise errors.
-	DB.DropTables()
+func Drop(path string) {
+	migrator, err := gomigrate.NewMigrator(DB.Dbx.DB, gomigrate.Postgres{}, path)
+	if err != nil {
+		log.Fatal("Error initializing migrations: ", err)
+	}
+
+	err = migrator.RollbackAll()
+	if err != nil {
+		log.Fatal("Error rolling back migrations: ", err)
+	}
 }
 
 // transact calls fn in a DB transaction. If dbh is a transaction, then it just calls

datastore/db_test.go

@@ -21,6 +21,7 @@ func init() {
 
 	// Reset DB
 	Connect()
-	Drop()
-	Create()
+	migrationsPath := "./migrations"
+	Drop(migrationsPath)
+	Create(migrationsPath)
 }

datastore/migrations/00001_AddUsers_down.sql

@@ -0,0 +1,5 @@
+-- bactdb
+-- Matthew R Dillon
+
+DROP TABLE users;
+

datastore/migrations/00001_AddUsers_up.sql

@@ -0,0 +1,19 @@
+-- bactdb
+-- Matthew R Dillon
+
+CREATE TABLE users (
+    id BIGSERIAL NOT NULL,
+    username CHARACTER VARYING(100),
+
+    createdat TIMESTAMP WITH TIME ZONE,
+    updatedat TIMESTAMP WITH TIME ZONE,
+    deletedat TIMESTAMP WITH TIME ZONE,
+
+    CONSTRAINT users_pkey PRIMARY KEY (id)
+);
+
+CREATE UNIQUE INDEX username_idx
+    ON users
+    USING btree
+    (username COLLATE pg_catalog."default");
+

datastore/users.go

@@ -12,9 +12,6 @@ import (
 
 func init() {
 	DB.AddTableWithName(models.User{}, "users").SetKeys(true, "Id")
-	createSQL = append(createSQL,
-		`CREATE UNIQUE INDEX username_idx ON users (username);`,
-	)
 }
 
 type usersStore struct {