dbconf: allow configuration to override a driver's import field

README.md

@@ -127,6 +127,17 @@ You may include as many environments as you like, and you can use the `-env` com
 
 goose will expand environment variables in the `open` element. For an example, see the Heroku section below.
 
+## Other Drivers
+goose knows about some common SQL drivers, but it can still be used to run Go-based migrations with any driver supported by database/sql. 
+
+To run Go-based migrations with another driver, specify its import path, as shown below.
+
+    customdriver:
+        driver: custom
+        open: custom open string
+        import: github.com/custom/driver
+
+NOTE: Because migrations written in SQL are executed directly by the goose binary, only drivers compiled into goose may be used for these migrations.
 
 ## Using goose with Heroku
 

db-sample/dbconf.yml

@@ -10,3 +10,8 @@ development:
 production:
     driver: postgres
     open: user=liam dbname=tester sslmode=verify-full
+
+customimport:
+    driver: customdriver
+    open: customdriver open
+    import: github.com/custom/driver

dbconf.go

@@ -65,7 +65,10 @@ func makeDBConfDetails(p, env string) (*DBConf, error) {
 
 	d := NewDBDriver(drv, open)
 
-	// XXX: allow an import entry to override DBDriver.Import
+	// allow the configuration to override the Import for this driver
+	if imprt, err := f.Get(fmt.Sprintf("%s.import", env)); err == nil {
+		d.Import = imprt
+	}
 
 	if !d.IsValid() {
 		return nil, errors.New(fmt.Sprintf("Invalid DBConf: %v", d))

dbconf_test.go

@@ -21,3 +21,17 @@ func TestBasics(t *testing.T) {
 		}
 	}
 }
+
+func TestImportOverride(t *testing.T) {
+
+	dbconf, err := makeDBConfDetails("db-sample", "customimport")
+	if err != nil {
+		t.Error("couldn't create DBConf")
+	}
+
+	got := dbconf.Driver.Import
+	want := "github.com/custom/driver"
+	if got != want {
+		t.Errorf("bad custom import. want %v got %v", got, want)
+	}
+}