Add --exit-code and --quiet flags to status command (#124)

Extending the `dbmate status` command with the ability to set an exit code or quiet output, for use in scripts.

Flag names were copied from `git diff` command.

README.md

@@ -93,7 +93,7 @@ dbmate drop      # drop the database
 dbmate migrate   # run any pending migrations
 dbmate rollback  # roll back the most recent migration
 dbmate down      # alias for rollback
-dbmate status    # show the status of all migrations
+dbmate status    # show the status of all migrations (supports --exit-code and --quiet)
 dbmate dump      # write the database schema.sql file
 dbmate wait      # wait for the database server to become available
 ```

main.go

@@ -17,9 +17,10 @@ func main() {
 
 	app := NewApp()
 	err := app.Run(os.Args)
+
 	if err != nil {
 		_, _ = fmt.Fprintf(os.Stderr, "Error: %s\n", err)
-		os.Exit(1)
+		os.Exit(2)
 	}
 }
 
@@ -105,8 +106,33 @@ func NewApp() *cli.App {
 		{
 			Name:  "status",
 			Usage: "List applied and pending migrations",
+			Flags: []cli.Flag{
+				cli.BoolFlag{
+					Name:  "exit-code",
+					Usage: "return 1 if there are pending migrations",
+				},
+				cli.BoolFlag{
+					Name:  "quiet",
+					Usage: "don't output any text (implies --exit-code)",
+				},
+			},
 			Action: action(func(db *dbmate.DB, c *cli.Context) error {
-				return db.Status()
+				setExitCode := c.Bool("exit-code")
+				quiet := c.Bool("quiet")
+				if quiet {
+					setExitCode = true
+				}
+
+				pending, err := db.Status(quiet)
+				if err != nil {
+					return err
+				}
+
+				if pending > 0 && setExitCode {
+					return cli.NewExitError("", 1)
+				}
+
+				return nil
 			}),
 		},
 		{

pkg/dbmate/db.go

@@ -492,26 +492,33 @@ func checkMigrationsStatus(db *DB) ([]statusResult, error) {
 }
 
 // Status shows the status of all migrations
-func (db *DB) Status() error {
+func (db *DB) Status(quiet bool) (int, error) {
 	results, err := checkMigrationsStatus(db)
 	if err != nil {
-		return err
+		return -1, err
 	}
 
 	var totalApplied int
+	var line string
 
 	for _, res := range results {
 		if res.applied {
-			fmt.Println("[X]", res.filename)
+			line = fmt.Sprintf("[X] %s", res.filename)
 			totalApplied++
 		} else {
-			fmt.Println("[ ]", res.filename)
+			line = fmt.Sprintf("[ ] %s", res.filename)
+		}
+		if !quiet {
+			fmt.Println(line)
 		}
 	}
 
+	totalPending := len(results) - totalApplied
+	if !quiet {
 		fmt.Println()
 		fmt.Printf("Applied: %d\n", totalApplied)
-	fmt.Printf("Pending: %d\n", len(results)-totalApplied)
+		fmt.Printf("Pending: %d\n", totalPending)
-
+	}
-	return nil
+
+	return totalPending, nil
 }