Allow reuse of an existing db connection when creating a MySQL Store

mysql/README.md

@@ -51,8 +51,16 @@ store := mysql.New(mysql.Config{
 })
 
 // Initialize custom config using connection string
-store := postgres.New(postgres.Config{
-	ConnectionURI:   "mysql://user:password@localhost:3306/fiber"
+store := mysql.New(mysql.Config{
+	ConnectionURI:   "<username>:<pw>@tcp(<HOST>:<port>)/<dbname>"
+	Reset:           false,
+	GCInterval:      10 * time.Second,
+})
+
+// Initialize custom config using sql db connection
+db, _ := sql.Open("mysql", "<username>:<pw>@tcp(<HOST>:<port>)/<dbname>")
+store := mysql.New(mysql.Config{
+	Db:              db,
 	Reset:           false,
 	GCInterval:      10 * time.Second,
 })
@@ -61,6 +69,11 @@ store := postgres.New(postgres.Config{
 ### Config
 ```go
 type Config struct {
+	// DB Will override ConnectionURI and all other authentication values if used
+	//
+	// Optional. Default is nil
+	Db *sql.DB
+	
 	// Connection string to use for DB. Will override all other authentication values if used
 	//
 	// Optional. Default is ""

mysql/config.go

@@ -1,12 +1,18 @@
 package mysql
 
 import (
+	"database/sql"
 	"fmt"
 	"time"
 )
 
 // Config defines the config for storage.
 type Config struct {
+	// DB Will override ConnectionURI and all other authentication values if used
+	//
+	// Optional. Default is nil
+	Db *sql.DB
+
 	// Connection string to use for DB. Will override all other authentication values if used
 	//
 	// Optional. Default is ""
@@ -63,6 +69,7 @@ type Config struct {
 
 // ConfigDefault is the default config
 var ConfigDefault = Config{
+	Db:              nil,
 	ConnectionURI:   "",
 	Host:            "127.0.0.1",
 	Port:            3306,

mysql/mysql.go

@@ -40,19 +40,27 @@ var (
 
 // New creates a new storage
 func New(config ...Config) *Storage {
+	var err error
+	var db *sql.DB
+
 	// Set default config
 	cfg := configDefault(config...)
 
-	// Create db
-	db, err := sql.Open("mysql", cfg.dsn())
-	if err != nil {
-		panic(err)
-	}
+	if cfg.Db != nil {
+		// Use passed db
+		db = cfg.Db
+	} else {
+		// Create db
+		db, err = sql.Open("mysql", cfg.dsn())
+		if err != nil {
+			panic(err)
+		}
 
-	// Set options
-	db.SetMaxOpenConns(cfg.maxOpenConns)
-	db.SetMaxIdleConns(cfg.maxIdleConns)
-	db.SetConnMaxLifetime(cfg.connMaxLifetime)
+		// Set options
+		db.SetMaxOpenConns(cfg.maxOpenConns)
+		db.SetMaxIdleConns(cfg.maxIdleConns)
+		db.SetConnMaxLifetime(cfg.connMaxLifetime)
+	}
 
 	// Ping database to ensure a connection has been made
 	if err := db.Ping(); err != nil {