feat(migrate-db): SQLite <-> .dump conversion and Download Migration in Overview

Binary: extend the migrate-db subcommand with --dump and --restore so a
SQLite database can be exported to a portable SQL text dump and rebuilt from
one, alongside the existing --dsn PostgreSQL copy. Implemented in Go via the
bundled sqlite driver (new database/dump_sqlite.go); no external sqlite3 client
is required. Add ExportPostgresToSQLite (reverse of MigrateData) to build a
SQLite .db from live PostgreSQL data, reusing the shared copyAllModels helper.

Overview: add a "Download Migration" item to Backup & Restore plus a
getMigration endpoint/service that returns a .dump on SQLite or a .db on
PostgreSQL, so the data can seed a panel on the other backend. Document the
endpoint in api-docs and translate the three new strings across all locales.

Tests: cover the destination-side copy (AutoMigrate + copyTable into SQLite)
and the dump/restore round-trip including quoted values. Ignore *.dump.

The x-ui.sh helper that drives this from the CLI is in PR #4910.

database/dump_sqlite.go

@@ -0,0 +1,218 @@
+package database
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"unicode/utf8"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+// DumpSQLite writes a portable SQL text dump of the SQLite database at srcPath
+// to outPath. The output mirrors the `sqlite3 .dump` format (schema + data +
+// indexes wrapped in a transaction), so it can be rebuilt with RestoreSQLite or
+// loaded by the sqlite3 CLI. The source database is opened read-only in effect
+// and left untouched.
+func DumpSQLite(srcPath, outPath string) error {
+	data, err := DumpSQLiteToBytes(srcPath)
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(outPath, data, 0o644)
+}
+
+// DumpSQLiteToBytes builds the same `sqlite3 .dump`-style SQL text as DumpSQLite
+// but returns it in memory, which the panel uses to stream a migration download.
+func DumpSQLiteToBytes(srcPath string) ([]byte, error) {
+	if _, err := os.Stat(srcPath); err != nil {
+		return nil, fmt.Errorf("source sqlite not found at %s: %w", srcPath, err)
+	}
+
+	gdb, err := gorm.Open(sqlite.Open(srcPath), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		return nil, err
+	}
+	sqlDB, err := gdb.DB()
+	if err != nil {
+		return nil, err
+	}
+	defer sqlDB.Close()
+
+	var b strings.Builder
+	b.WriteString("PRAGMA foreign_keys=OFF;\n")
+	b.WriteString("BEGIN TRANSACTION;\n")
+
+	// Tables in creation order, each followed by its data.
+	type object struct{ name, ddl string }
+	var tables []object
+	rows, err := sqlDB.Query(`SELECT name, sql FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%' AND sql IS NOT NULL ORDER BY rowid`)
+	if err != nil {
+		return nil, err
+	}
+	for rows.Next() {
+		var o object
+		if err := rows.Scan(&o.name, &o.ddl); err != nil {
+			rows.Close()
+			return nil, err
+		}
+		tables = append(tables, o)
+	}
+	if err := rows.Err(); err != nil {
+		rows.Close()
+		return nil, err
+	}
+	rows.Close()
+
+	for _, t := range tables {
+		b.WriteString(t.ddl)
+		b.WriteString(";\n")
+		if err := dumpTableData(sqlDB, t.name, &b); err != nil {
+			return nil, err
+		}
+	}
+
+	// AUTOINCREMENT bookkeeping, restored verbatim like the sqlite3 CLI does.
+	if sqliteTableExists(sqlDB, "sqlite_sequence") {
+		b.WriteString("DELETE FROM sqlite_sequence;\n")
+		if err := dumpTableData(sqlDB, "sqlite_sequence", &b); err != nil {
+			return nil, err
+		}
+	}
+
+	// Indexes, triggers and views after the data is in place.
+	rows2, err := sqlDB.Query(`SELECT sql FROM sqlite_master WHERE type IN ('index','trigger','view') AND sql IS NOT NULL ORDER BY rowid`)
+	if err != nil {
+		return nil, err
+	}
+	for rows2.Next() {
+		var ddl string
+		if err := rows2.Scan(&ddl); err != nil {
+			rows2.Close()
+			return nil, err
+		}
+		b.WriteString(ddl)
+		b.WriteString(";\n")
+	}
+	if err := rows2.Err(); err != nil {
+		rows2.Close()
+		return nil, err
+	}
+	rows2.Close()
+
+	b.WriteString("COMMIT;\n")
+
+	return []byte(b.String()), nil
+}
+
+// RestoreSQLite rebuilds a SQLite database at dstPath from a SQL text dump
+// produced by DumpSQLite (or `sqlite3 .dump`). dstPath must not already exist so
+// an existing database is never clobbered silently.
+func RestoreSQLite(dumpPath, dstPath string) error {
+	script, err := os.ReadFile(dumpPath)
+	if err != nil {
+		return err
+	}
+	if _, err := os.Stat(dstPath); err == nil {
+		return fmt.Errorf("destination already exists: %s", dstPath)
+	}
+
+	gdb, err := gorm.Open(sqlite.Open(dstPath), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		return err
+	}
+	sqlDB, err := gdb.DB()
+	if err != nil {
+		return err
+	}
+
+	// mattn/go-sqlite3 executes every statement in a multi-statement string.
+	if _, err := sqlDB.Exec(string(script)); err != nil {
+		sqlDB.Close()
+		os.Remove(dstPath)
+		return fmt.Errorf("restore failed: %w", err)
+	}
+	return sqlDB.Close()
+}
+
+// dumpTableData appends one INSERT statement per row of table to b.
+func dumpTableData(db *sql.DB, table string, b *strings.Builder) error {
+	rows, err := db.Query(`SELECT * FROM "` + table + `"`)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	cols, err := rows.Columns()
+	if err != nil {
+		return err
+	}
+	n := len(cols)
+	prefix := `INSERT INTO "` + table + `" VALUES(`
+
+	for rows.Next() {
+		vals := make([]any, n)
+		ptrs := make([]any, n)
+		for i := range vals {
+			ptrs[i] = &vals[i]
+		}
+		if err := rows.Scan(ptrs...); err != nil {
+			return err
+		}
+		b.WriteString(prefix)
+		for i, v := range vals {
+			if i > 0 {
+				b.WriteByte(',')
+			}
+			b.WriteString(sqliteLiteral(v))
+		}
+		b.WriteString(");\n")
+	}
+	return rows.Err()
+}
+
+// sqliteLiteral renders a scanned column value as a SQLite SQL literal.
+func sqliteLiteral(v any) string {
+	switch x := v.(type) {
+	case nil:
+		return "NULL"
+	case int64:
+		return strconv.FormatInt(x, 10)
+	case float64:
+		return strconv.FormatFloat(x, 'g', -1, 64)
+	case bool:
+		if x {
+			return "1"
+		}
+		return "0"
+	case string:
+		return quoteSQLiteText(x)
+	case []byte:
+		if utf8.Valid(x) {
+			return quoteSQLiteText(string(x))
+		}
+		var sb strings.Builder
+		sb.WriteString("X'")
+		for _, c := range x {
+			fmt.Fprintf(&sb, "%02x", c)
+		}
+		sb.WriteByte('\'')
+		return sb.String()
+	default:
+		return quoteSQLiteText(fmt.Sprintf("%v", x))
+	}
+}
+
+func quoteSQLiteText(s string) string {
+	return "'" + strings.ReplaceAll(s, "'", "''") + "'"
+}
+
+func sqliteTableExists(db *sql.DB, name string) bool {
+	var found string
+	err := db.QueryRow(`SELECT name FROM sqlite_master WHERE type='table' AND name=?`, name).Scan(&found)
+	return err == nil
+}

database/dump_sqlite_test.go

@@ -0,0 +1,137 @@
+package database
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/mhsanaei/3x-ui/v3/database/model"
+	"github.com/mhsanaei/3x-ui/v3/xray"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+// TestCopyAllModelsIntoSQLite exercises the same AutoMigrate + copyTable
+// machinery that ExportPostgresToSQLite relies on, but with a SQLite source so
+// it needs no external database. The Postgres source path uses identical gorm
+// reads (see MigrateData), so this validates the destination-side copy.
+func TestCopyAllModelsIntoSQLite(t *testing.T) {
+	dir := t.TempDir()
+	srcPath := filepath.Join(dir, "src.db")
+	dstPath := filepath.Join(dir, "dst.db")
+
+	src, err := gorm.Open(sqlite.Open(srcPath), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		t.Fatalf("open src: %v", err)
+	}
+	defer closeGorm(src)
+	for _, m := range migrationModels() {
+		if err := src.AutoMigrate(m); err != nil {
+			t.Fatalf("automigrate src %T: %v", m, err)
+		}
+	}
+
+	// Seed a few rows across parent/child tables and a composite-PK table.
+	if err := src.Create(&model.User{Username: "admin", Password: "x"}).Error; err != nil {
+		t.Fatalf("seed user: %v", err)
+	}
+	if err := src.Create(&model.Inbound{UserId: 1, Remark: "in", Port: 443, Protocol: "vless", Tag: "inbound-443"}).Error; err != nil {
+		t.Fatalf("seed inbound: %v", err)
+	}
+	if err := src.Create(&xray.ClientTraffic{InboundId: 1, Email: "a@b.c", Enable: true, Up: 10, Down: 20}).Error; err != nil {
+		t.Fatalf("seed traffic: %v", err)
+	}
+
+	dst, err := gorm.Open(sqlite.Open(dstPath), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		t.Fatalf("open dst: %v", err)
+	}
+	defer closeGorm(dst)
+	if err := copyAllModels(src, dst); err != nil {
+		t.Fatalf("copyAllModels: %v", err)
+	}
+
+	for _, tc := range []struct {
+		model any
+		want  int64
+	}{
+		{&model.User{}, 1},
+		{&model.Inbound{}, 1},
+		{&xray.ClientTraffic{}, 1},
+	} {
+		var got int64
+		if err := dst.Model(tc.model).Count(&got).Error; err != nil {
+			t.Fatalf("count %T: %v", tc.model, err)
+		}
+		if got != tc.want {
+			t.Errorf("%T: got %d rows, want %d", tc.model, got, tc.want)
+		}
+	}
+
+	// Spot-check a copied value survived the round-trip.
+	var ct xray.ClientTraffic
+	if err := dst.Where("email = ?", "a@b.c").First(&ct).Error; err != nil {
+		t.Fatalf("read back traffic: %v", err)
+	}
+	if ct.Up != 10 || ct.Down != 20 || !ct.Enable {
+		t.Errorf("traffic mismatch: %+v", ct)
+	}
+}
+
+// TestDumpAndRestoreSQLiteRoundTrip dumps a seeded SQLite db to .dump text and
+// rebuilds it, asserting the row survives.
+func TestDumpAndRestoreSQLiteRoundTrip(t *testing.T) {
+	dir := t.TempDir()
+	srcPath := filepath.Join(dir, "src.db")
+	dumpPath := filepath.Join(dir, "out.dump")
+	dstPath := filepath.Join(dir, "rebuilt.db")
+
+	src, err := gorm.Open(sqlite.Open(srcPath), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		t.Fatalf("open src: %v", err)
+	}
+	if err := src.AutoMigrate(&model.Setting{}); err != nil {
+		t.Fatalf("automigrate: %v", err)
+	}
+	if err := src.Create(&model.Setting{Key: "secret", Value: "o'brien \"quote\""}).Error; err != nil {
+		t.Fatalf("seed: %v", err)
+	}
+	if sqlDB, _ := src.DB(); sqlDB != nil {
+		sqlDB.Close()
+	}
+
+	if err := DumpSQLite(srcPath, dumpPath); err != nil {
+		t.Fatalf("DumpSQLite: %v", err)
+	}
+	if fi, err := os.Stat(dumpPath); err != nil || fi.Size() == 0 {
+		t.Fatalf("dump missing/empty: %v", err)
+	}
+	if err := RestoreSQLite(dumpPath, dstPath); err != nil {
+		t.Fatalf("RestoreSQLite: %v", err)
+	}
+
+	dst, err := gorm.Open(sqlite.Open(dstPath), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		t.Fatalf("open dst: %v", err)
+	}
+	defer closeGorm(dst)
+	var s model.Setting
+	if err := dst.Where("key = ?", "secret").First(&s).Error; err != nil {
+		t.Fatalf("read back: %v", err)
+	}
+	if s.Value != "o'brien \"quote\"" {
+		t.Errorf("value mismatch after round-trip: %q", s.Value)
+	}
+}
+
+// closeGorm closes the underlying *sql.DB so Windows can delete the temp file.
+func closeGorm(db *gorm.DB) {
+	if db == nil {
+		return
+	}
+	if s, err := db.DB(); err == nil {
+		s.Close()
+	}
+}

database/migrate_data.go

@@ -86,6 +86,15 @@ func MigrateData(srcPath, dstDSN string) error {
 		}
 	}
 
+	// Empty the destination tables so the migration is idempotent: a fresh
+	// PostgreSQL DB already holds an auto-seeded admin (id=1) from any prior
+	// panel start, and a partially-failed earlier run leaves rows behind. Either
+	// way a plain INSERT with explicit ids would collide on users_pkey, so clear
+	// our tables (only) before copying.
+	if err := truncatePostgresTables(dst, migrationModels()); err != nil {
+		return fmt.Errorf("clear destination tables: %w", err)
+	}
+
 	totalRows := 0
 	for _, m := range migrationModels() {
 		n, err := copyTable(src, dst, m)
@@ -105,6 +114,62 @@ func MigrateData(srcPath, dstDSN string) error {
 	return nil
 }
 
+// ExportPostgresToSQLite copies every row from the PostgreSQL database described
+// by srcDSN into a fresh SQLite file at dstPath. It is the reverse of
+// MigrateData and is used to hand a PostgreSQL-backed panel a portable .db file.
+// dstPath is created/overwritten; the PostgreSQL source is left untouched.
+func ExportPostgresToSQLite(srcDSN, dstPath string) error {
+	if srcDSN == "" {
+		return errors.New("source DSN is required")
+	}
+	if err := os.MkdirAll(path.Dir(dstPath), 0755); err != nil {
+		return err
+	}
+	// Start from an empty file so AutoMigrate creates the canonical schema.
+	if err := os.Remove(dstPath); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	src, err := gorm.Open(postgres.Open(srcDSN), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		return fmt.Errorf("open postgres source: %w", err)
+	}
+	srcSQL, err := src.DB()
+	if err != nil {
+		return err
+	}
+	defer srcSQL.Close()
+
+	// No WAL: keep all data in the main file so it is complete once closed.
+	dst, err := gorm.Open(sqlite.Open(dstPath+"?_busy_timeout=10000"), &gorm.Config{Logger: logger.Discard})
+	if err != nil {
+		return fmt.Errorf("open sqlite destination: %w", err)
+	}
+	dstSQL, err := dst.DB()
+	if err != nil {
+		return err
+	}
+	defer dstSQL.Close()
+
+	return copyAllModels(src, dst)
+}
+
+// copyAllModels (re)creates the schema on dst and copies every migrated table
+// from src to dst in FK-safe order. src/dst may be any gorm backend.
+func copyAllModels(src, dst *gorm.DB) error {
+	for _, m := range migrationModels() {
+		if err := dst.AutoMigrate(m); err != nil {
+			return fmt.Errorf("AutoMigrate %T: %w", m, err)
+		}
+	}
+	for _, m := range migrationModels() {
+		if _, err := copyTable(src, dst, m); err != nil {
+			return fmt.Errorf("copy %T: %w", m, err)
+		}
+	}
+	return nil
+}
+
 func copyTable(src, dst *gorm.DB, mdl any) (int, error) {
 	const batchSize = 500
 
@@ -157,6 +222,26 @@ func copyTable(src, dst *gorm.DB, mdl any) (int, error) {
 	return total, nil
 }
 
+// truncatePostgresTables empties every migrated table on dst in a single
+// statement, resetting identity sequences. CASCADE covers the inbound/client
+// foreign keys regardless of insertion order. Only the panel's own tables are
+// touched, never the rest of the schema.
+func truncatePostgresTables(dst *gorm.DB, models []any) error {
+	tables := make([]string, 0, len(models))
+	for _, m := range models {
+		stmt := &gorm.Statement{DB: dst}
+		if err := stmt.Parse(m); err != nil {
+			return err
+		}
+		tables = append(tables, `"`+stmt.Schema.Table+`"`)
+	}
+	if len(tables) == 0 {
+		return nil
+	}
+	log.Println("Clearing destination tables...")
+	return dst.Exec("TRUNCATE TABLE " + strings.Join(tables, ", ") + " RESTART IDENTITY CASCADE").Error
+}
+
 // resetPostgresSequences advances each migrated table's id sequence past MAX(id),
 // otherwise the next INSERT-without-id would clash with copied rows.
 func resetPostgresSequences(dst *gorm.DB) error {