model: Detect if database is empty

An empty database requires to add the metadata table with the version
entry to make migrations possible. Thus this detection will be required.

1 files changed, 25 insertions, 0 deletions

diff --git a/model/database.go b/model/database.go
index 3953c92..16a6cea 100644
--- a/model/database.go
+++ b/model/database.go
@@ -57,8 +57,33 @@ func Transaction(f func(*sql.Tx) error) error {
 	return tx.Commit()
 }
 
+func isDatabaseEmpty(tx *sql.Tx) bool {
+	cmd := `SELECT COUNT(*) FROM sqlite_master WHERE type='table'`
+	rows, err := tx.Query(cmd)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer rows.Close()
+
+	if !rows.Next() {
+		log.Fatalf("No rows on request of database table number")
+	}
+
+	var number int
+	err = rows.Scan(&number)
+	if err != nil {
+		log.Fatalf("Failed to scan number of database tables to integer")
+	}
+
+	return number == 0
+}
+
 func MigrateDatabase() {
 	err := Transaction(func(tx *sql.Tx) error {
+		if isDatabaseEmpty(tx) {
+			log.Println("Starting with empty database")
+		}
+
 		query, err := GetSql(`migrate`)
 		if err != nil {
 			log.Fatal(err)