What causes "endpoint[%d]: invalid mux pattern: %w" in gofr-dev/gofr?

Balance all braces and give every variable a name: /api/{id}.

endpoint[%d]: invalid mux pattern: %w

Error message

endpoint[%d]: invalid mux pattern: %w

What it means

validateEndpointPath detected the path uses gorilla/mux variable syntax ({var}) and validateMuxPattern found the pattern syntactically invalid. RBAC paths must be valid mux patterns so routing and permission matching agree.

Source

Thrown at pkg/gofr/rbac/config.go:222

	// Reject wildcard patterns
	if err := c.checkWildcardPattern(path, index); err != nil {
		return err
	}

	// Reject old regex patterns
	if err := c.checkRegexPattern(path, index); err != nil {
		return err
	}

	// Reject regex indicators outside of variable constraints
	if err := c.checkRegexIndicators(path, index); err != nil {
		return err
	}

	// Validate mux pattern syntax if it contains variables
	if isMuxPattern(path) {
		if err := validateMuxPattern(path); err != nil {
			return fmt.Errorf("endpoint[%d]: invalid mux pattern: %w", index, err)
		}
	}

	return nil
}

// checkWildcardPattern checks if path contains wildcard pattern.
func (*Config) checkWildcardPattern(path string, index int) error {
	if strings.Contains(path, "/*") {
		return fmt.Errorf("endpoint[%d]: %w: %s. Examples: /api/{resource} for single-level or /api/{path:.*} for multi-level",
			index, errWildcardPatternNotSupported, path)
	}

	return nil
}

// checkRegexPattern checks if path contains old regex pattern.
func (*Config) checkRegexPattern(path string, index int) error {

View on GitHub (pinned to 187eb24962)

Solutions

Balance all braces and give every variable a name: /api/{id}.
If using a constraint, keep the colon and a valid regex: /api/users/{id:[0-9]+}.
Replace multi-level needs with /api/{path:.*} instead of several broken variables.
Test the pattern against your mux router to confirm it compiles/matches.

Example fix

// before
path: "/api/users/{id"
// after
path: "/api/users/{id:[0-9]+}"

Defensive patterns

Strategy: validation

Validate before calling

func validMuxPath(p string) bool {
    depth := 0
    for _, r := range p {
        switch r {
        case '{':
            depth++
        case '}':
            depth--
            if depth < 0 { return false }
        }
    }
    if depth != 0 { return false }
    for _, m := range muxVarRe.FindAllStringSubmatch(p, -1) {
        if m[1] == "" { return false } // empty variable name
    }
    return true
}
var muxVarRe = regexp.MustCompile(`\{([^:}]*)(:[^}]*)?\}`)

Try / catch

for i, ep := range endpoints {
    if !validMuxPath(ep.Path) { return fmt.Errorf("endpoint[%d]: bad mux pattern %q", i, ep.Path) }
}

Prevention

Test each pattern against the real mux router in unit tests.
Keep brace count balanced; never leave an unclosed {var.
Always name variables; provide valid regex constraints after ':'.
Only copy patterns from mux documentation, not regex routers.

When it happens

Trigger: An endpoint path like /api/{id or /api/{id:} or /api/users[0]} — malformed braces, empty variable names, or invalid constraint expressions — passed to EnableRBAC/LoadPermissions.

Common situations: Hand-writing mux patterns with unbalanced braces; copying patterns from regex-style routers; typos in variable constraints like {id:[a-z instead of {id:[a-z]+}.

Related errors

AI-assisted analysis of gofr-dev/gofr@187eb24962 (2026-09-01). Data as JSON: /api/errors/0fac0f06da77da14. Report an issue: GitHub.