dbconf: split out separate DBDriver struct to encapsulate the info required for a given driver. as a bonus, we now import the correct package for Go migrations based on the driver - previously, we imported postgres only.

cmd_status.go

@@ -35,7 +35,7 @@ func statusRun(cmd *Command, args ...string) {
 		log.Fatal(e)
 	}
 
-	db, e := sql.Open(conf.Driver, conf.OpenStr)
+	db, e := sql.Open(conf.Driver.Name, conf.Driver.OpenStr)
 	if e != nil {
 		log.Fatal("couldn't open DB:", e)
 	}

dbconf.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"flag"
 	"fmt"
 	"github.com/kylelemons/go-gypsy/yaml"
@@ -13,11 +14,18 @@ import (
 var dbPath = flag.String("path", "db", "folder containing db info")
 var dbEnv = flag.String("env", "development", "which DB environment to use")
 
+// DBDriver encapsulates the info needed to work with
+// a specific database driver
+type DBDriver struct {
+	Name    string
+	OpenStr string
+	Import  string
+}
+
 type DBConf struct {
 	MigrationsDir string
 	Env           string
-	Driver        string
+	Driver        DBDriver
-	OpenStr       string
 }
 
 // default helper - makes a DBConf from the dbPath and dbEnv flags
@@ -55,10 +63,47 @@ func makeDBConfDetails(p, env string) (*DBConf, error) {
 		}
 	}
 
+	d := NewDBDriver(drv, open)
+
+	// XXX: allow an import entry to override DBDriver.Import
+
+	if !d.IsValid() {
+		return nil, errors.New(fmt.Sprintf("Invalid DBConf: %v", d))
+	}
+
 	return &DBConf{
 		MigrationsDir: filepath.Join(p, "migrations"),
 		Env:           env,
-		Driver:        drv,
+		Driver:        d,
-		OpenStr:       open,
 	}, nil
 }
+
+// Create a new DBDriver and populate driver specific
+// fields for drivers that we know about.
+// Further customization may be done in NewDBConf
+func NewDBDriver(name, open string) DBDriver {
+
+	d := DBDriver{
+		Name:    name,
+		OpenStr: open,
+	}
+
+	switch name {
+	case "postgres":
+		d.Import = "github.com/lib/pq"
+
+	case "mymysql":
+		d.Import = "github.com/ziutek/mymysql/godrv"
+	}
+
+	return d
+}
+
+// ensure we have enough info about this driver
+func (drv *DBDriver) IsValid() bool {
+	if len(drv.Import) == 0 {
+		return false
+	}
+
+	return true
+}

dbconf_test.go

@@ -12,7 +12,7 @@ func TestBasics(t *testing.T) {
 		t.Error("couldn't create DBConf")
 	}
 
-	got := []string{dbconf.MigrationsDir, dbconf.Env, dbconf.Driver, dbconf.OpenStr}
+	got := []string{dbconf.MigrationsDir, dbconf.Env, dbconf.Driver.Name, dbconf.Driver.OpenStr}
 	want := []string{"db-sample/migrations", "test", "postgres", "user=liam dbname=tester sslmode=disable"}
 
 	for i, s := range got {

migrate.go

@@ -42,7 +42,7 @@ type MigrationMap struct {
 
 func runMigrations(conf *DBConf, migrationsDir string, target int64) {
 
-	db, err := sql.Open(conf.Driver, conf.OpenStr)
+	db, err := sql.Open(conf.Driver.Name, conf.Driver.OpenStr)
 	if err != nil {
 		log.Fatal("couldn't open DB:", err)
 	}
@@ -267,7 +267,7 @@ func createVersionTable(conf *DBConf, db *sql.DB) error {
 // their own DB instance
 func getDBVersion(conf *DBConf) int64 {
 
-	db, err := sql.Open(conf.Driver, conf.OpenStr)
+	db, err := sql.Open(conf.Driver.Name, conf.Driver.OpenStr)
 	if err != nil {
 		log.Fatal("couldn't open DB:", err)
 	}

migration_go.go

@@ -12,8 +12,7 @@ import (
 
 type TemplateData struct {
 	Version   int64
-	DBDriver  string
+	Driver    DBDriver
-	DBOpen    string
 	Direction bool
 	Func      string
 }
@@ -41,8 +40,7 @@ func runGoMigration(conf *DBConf, path string, version int64, direction bool) er
 
 	td := &TemplateData{
 		Version:   version,
-		DBDriver:  conf.Driver,
+		Driver:    conf.Driver,
-		DBOpen:    conf.OpenStr,
 		Direction: direction,
 		Func:      fmt.Sprintf("%v_%v", directionStr, version),
 	}
@@ -76,13 +74,13 @@ package main
 
 import (
 	"database/sql"
-	_ "github.com/lib/pq"
+	_ "{{.Driver.Import}}"
 	"log"
 	"fmt"
 )
 
 func main() {
-	db, err := sql.Open("{{.DBDriver}}", "{{.DBOpen}}")
+	db, err := sql.Open("{{.Driver.Name}}", "{{.Driver.OpenStr}}")
 	if err != nil {
 		log.Fatal("failed to open DB:", err)
 	}