init - add project files

tools/jet-2.12.0/generator/mysql/mysql_generator.go

@@ -0,0 +1,118 @@
+package mysql
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/go-jet/jet/v2/generator/metadata"
+	"github.com/go-jet/jet/v2/generator/template"
+	"github.com/go-jet/jet/v2/mysql"
+	mysqldr "github.com/go-sql-driver/mysql"
+)
+
+const mysqlMaxConns = 10
+
+// DBConnection contains MySQL connection details
+type DBConnection struct {
+	Host     string
+	Port     int
+	User     string
+	Password string
+	Params   string
+
+	DBName string
+}
+
+// Generate generates jet files at destination dir from database connection details
+func Generate(destDir string, dbConn DBConnection, generatorTemplate ...template.Template) error {
+	connectionString := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s", dbConn.User, dbConn.Password, dbConn.Host, dbConn.Port, dbConn.DBName)
+	if dbConn.Params != "" {
+		connectionString += "?" + dbConn.Params
+	}
+
+	db, err := openConnection(connectionString)
+	if err != nil {
+		return fmt.Errorf("failed to open db connection: %w", err)
+	}
+	defer db.Close()
+
+	err = generate(db, dbConn.DBName, destDir, generatorTemplate...)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// GenerateDSN opens connection via DSN string and does everything what Generate does.
+func GenerateDSN(dsn, destDir string, templates ...template.Template) error {
+	// Special case for go mysql driver. It does not understand schema,
+	// so we need to trim it before passing to generator
+	// https://github.com/go-sql-driver/mysql#dsn-data-source-name
+	idx := strings.Index(dsn, "://")
+	if idx != -1 {
+		dsn = dsn[idx+len("://"):]
+	}
+
+	cfg, err := mysqldr.ParseDSN(dsn)
+	if err != nil {
+		return fmt.Errorf("failed to parse DSN: %w", err)
+	}
+	if cfg.DBName == "" {
+		return errors.New("database name is required")
+	}
+
+	db, err := openConnection(dsn)
+	if err != nil {
+		return fmt.Errorf("failed to open db connection: %w", err)
+	}
+	defer db.Close()
+
+	err = generate(db, cfg.DBName, destDir, templates...)
+	if err != nil {
+		return fmt.Errorf("failed to generate: %w", err)
+	}
+
+	return nil
+}
+
+func openConnection(connectionString string) (*sql.DB, error) {
+	fmt.Println("Connecting to MySQL database...")
+	db, err := sql.Open("mysql", connectionString)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open mysql connection: %w", err)
+	}
+
+	db.SetMaxOpenConns(mysqlMaxConns)
+	db.SetMaxIdleConns(mysqlMaxConns)
+
+	err = db.Ping()
+	if err != nil {
+		return nil, fmt.Errorf("failed to ping database: %w", err)
+	}
+
+	return db, nil
+}
+
+func generate(db *sql.DB, dbName, destDir string, templates ...template.Template) error {
+	fmt.Println("Retrieving database information...")
+	// No schemas in MySQL
+	schemaMetaData, err := metadata.GetSchema(db, &mySqlQuerySet{}, dbName)
+	if err != nil {
+		return fmt.Errorf("failed to get '%s' database metadata: %w", dbName, err)
+	}
+
+	genTemplate := template.Default(mysql.Dialect)
+	if len(templates) > 0 {
+		genTemplate = templates[0]
+	}
+
+	err = template.ProcessSchema(destDir, schemaMetaData, genTemplate)
+	if err != nil {
+		return fmt.Errorf("failed to process '%s' database: %w", schemaMetaData.Name, err)
+	}
+
+	return nil
+}