fix: enable foreign key check for sqlite (#863)

Co-authored-by: Alessandro (Ale) Segala <43508+ItalyPaleAle@users.noreply.github.com>

backend/internal/bootstrap/db_bootstrap.go

@@ -86,9 +86,6 @@ func connectDatabase() (db *gorm.DB, err error) {
 		if common.EnvConfig.DbConnectionString == "" {
 			return nil, errors.New("missing required env var 'DB_CONNECTION_STRING' for SQLite database")
 		}
-		if !strings.HasPrefix(common.EnvConfig.DbConnectionString, "file:") {
-			return nil, errors.New("invalid value for env var 'DB_CONNECTION_STRING': does not begin with 'file:'")
-		}
 		sqliteutil.RegisterSqliteFunctions()
 		connString, err := parseSqliteConnectionString(common.EnvConfig.DbConnectionString)
 		if err != nil {
@@ -123,25 +120,43 @@ func connectDatabase() (db *gorm.DB, err error) {
 	return nil, err
 }
 
-// The official C implementation of SQLite allows some additional properties in the connection string
-// that are not supported in the in the modernc.org/sqlite driver, and which must be passed as PRAGMA args instead.
-// To ensure that people can use similar args as in the C driver, which was also used by Pocket ID
-// previously (via github.com/mattn/go-sqlite3), we are converting some options.
 func parseSqliteConnectionString(connString string) (string, error) {
 	if !strings.HasPrefix(connString, "file:") {
 		connString = "file:" + connString
 	}
 
+	// Check if we're using an in-memory database
+	isMemoryDB := isSqliteInMemory(connString)
+
+	// Parse the connection string
 	connStringUrl, err := url.Parse(connString)
 	if err != nil {
 		return "", fmt.Errorf("failed to parse SQLite connection string: %w", err)
 	}
 
+	// Convert options for the old SQLite driver to the new one
+	convertSqlitePragmaArgs(connStringUrl)
+
+	// Add the default and required params
+	err = addSqliteDefaultParameters(connStringUrl, isMemoryDB)
+	if err != nil {
+		return "", fmt.Errorf("invalid SQLite connection string: %w", err)
+	}
+
+	return connStringUrl.String(), nil
+}
+
+// The official C implementation of SQLite allows some additional properties in the connection string
+// that are not supported in the in the modernc.org/sqlite driver, and which must be passed as PRAGMA args instead.
+// To ensure that people can use similar args as in the C driver, which was also used by Pocket ID
+// previously (via github.com/mattn/go-sqlite3), we are converting some options.
+// Note this function updates connStringUrl.
+func convertSqlitePragmaArgs(connStringUrl *url.URL) {
 	// Reference: https://github.com/mattn/go-sqlite3?tab=readme-ov-file#connection-string
 	// This only includes a subset of options, excluding those that are not relevant to us
 	qs := make(url.Values, len(connStringUrl.Query()))
 	for k, v := range connStringUrl.Query() {
-		switch k {
+		switch strings.ToLower(k) {
 		case "_auto_vacuum", "_vacuum":
 			qs.Add("_pragma", "auto_vacuum("+v[0]+")")
 		case "_busy_timeout", "_timeout":
@@ -162,9 +177,123 @@ func parseSqliteConnectionString(connString string) (string, error) {
 		}
 	}
 
+	// Update the connStringUrl object
+	connStringUrl.RawQuery = qs.Encode()
+}
+
+// Adds the default (and some required) parameters to the SQLite connection string.
+// Note this function updates connStringUrl.
+func addSqliteDefaultParameters(connStringUrl *url.URL, isMemoryDB bool) error {
+	// This function include code adapted from https://github.com/dapr/components-contrib/blob/v1.14.6/
+	// Copyright (C) 2023 The Dapr Authors
+	// License: Apache2
+	const defaultBusyTimeout = 2500 * time.Millisecond
+
+	// Get the "query string" from the connection string if present
+	qs := connStringUrl.Query()
+	if len(qs) == 0 {
+		qs = make(url.Values, 2)
+	}
+
+	// If the database is in-memory, we must ensure that cache=shared is set
+	if isMemoryDB {
+		qs["cache"] = []string{"shared"}
+	}
+
+	// Check if the database is read-only or immutable
+	isReadOnly := false
+	if len(qs["mode"]) > 0 {
+		// Keep the first value only
+		qs["mode"] = []string{
+			strings.ToLower(qs["mode"][0]),
+		}
+		if qs["mode"][0] == "ro" {
+			isReadOnly = true
+		}
+	}
+	if len(qs["immutable"]) > 0 {
+		// Keep the first value only
+		qs["immutable"] = []string{
+			strings.ToLower(qs["immutable"][0]),
+		}
+		if qs["immutable"][0] == "1" {
+			isReadOnly = true
+		}
+	}
+
+	// We do not want to override a _txlock if set, but we'll show a warning if it's not "immediate"
+	if len(qs["_txlock"]) > 0 {
+		// Keep the first value only
+		qs["_txlock"] = []string{
+			strings.ToLower(qs["_txlock"][0]),
+		}
+		if qs["_txlock"][0] != "immediate" {
+			slog.Warn("SQLite connection is being created with a _txlock different from the recommended value 'immediate'")
+		}
+	} else {
+		qs["_txlock"] = []string{"immediate"}
+	}
+
+	// Add pragma values
+	var hasBusyTimeout, hasJournalMode bool
+	if len(qs["_pragma"]) == 0 {
+		qs["_pragma"] = make([]string, 0, 3)
+	} else {
+		for _, p := range qs["_pragma"] {
+			p = strings.ToLower(p)
+			switch {
+			case strings.HasPrefix(p, "busy_timeout"):
+				hasBusyTimeout = true
+			case strings.HasPrefix(p, "journal_mode"):
+				hasJournalMode = true
+			case strings.HasPrefix(p, "foreign_keys"):
+				return errors.New("found forbidden option '_pragma=foreign_keys' in the connection string")
+			}
+		}
+	}
+	if !hasBusyTimeout {
+		qs["_pragma"] = append(qs["_pragma"], fmt.Sprintf("busy_timeout(%d)", defaultBusyTimeout.Milliseconds()))
+	}
+	if !hasJournalMode {
+		switch {
+		case isMemoryDB:
+			// For in-memory databases, set the journal to MEMORY, the only allowed option besides OFF (which would make transactions ineffective)
+			qs["_pragma"] = append(qs["_pragma"], "journal_mode(MEMORY)")
+		case isReadOnly:
+			// Set the journaling mode to "DELETE" (the default) if the database is read-only
+			qs["_pragma"] = append(qs["_pragma"], "journal_mode(DELETE)")
+		default:
+			// Enable WAL
+			qs["_pragma"] = append(qs["_pragma"], "journal_mode(WAL)")
+		}
+	}
+
+	// Forcefully enable foreign keys
+	qs["_pragma"] = append(qs["_pragma"], "foreign_keys(1)")
+
+	// Update the connStringUrl object
 	connStringUrl.RawQuery = qs.Encode()
 
-	return connStringUrl.String(), nil
+	return nil
+}
+
+// isSqliteInMemory returns true if the connection string is for an in-memory database.
+func isSqliteInMemory(connString string) bool {
+	lc := strings.ToLower(connString)
+
+	// First way to define an in-memory database is to use ":memory:" or "file::memory:" as connection string
+	if strings.HasPrefix(lc, ":memory:") || strings.HasPrefix(lc, "file::memory:") {
+		return true
+	}
+
+	// Another way is to pass "mode=memory" in the "query string"
+	idx := strings.IndexRune(lc, '?')
+	if idx < 0 {
+		return false
+	}
+	qs, _ := url.ParseQuery(lc[(idx + 1):])
+
+	return len(qs["mode"]) > 0 && qs["mode"][0] == "memory"
 }
 
 func getGormLogger() gormLogger.Interface {