{"id":"7a9c339884dcdd58","repo":"gofiber/fiber","slug":"len-constraint-requires-an-argument","errorCode":null,"errorMessage":"len constraint requires an argument","messagePattern":"len constraint requires an argument","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"constraint.go","lineNumber":389,"sourceCode":"\nfunc (maxLenConstraintType) Execute(param string, data []any) bool {\n\tif len(data) == 0 {\n\t\treturn false\n\t}\n\tlimit, ok := data[0].(int)\n\tif !ok {\n\t\treturn false\n\t}\n\treturn len(param) <= limit\n}\n\ntype lenConstraintType struct{}\n\nfunc (lenConstraintType) Name() string { return ConstraintLen }\nfunc (lenConstraintType) Analyze(args []string) ([]any, error) {\n\targs = parseConstraintArgs(args)\n\tif len(args) == 0 {\n\t\treturn nil, errors.New(\"len constraint requires an argument\")\n\t}\n\tn, err := strconv.Atoi(args[0])\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"parse constraint arg: %w\", err)\n\t}\n\treturn []any{n}, nil\n}\n\nfunc (lenConstraintType) Execute(param string, data []any) bool {\n\tif len(data) == 0 {\n\t\treturn false\n\t}\n\tlimit, ok := data[0].(int)\n\tif !ok {\n\t\treturn false\n\t}\n\treturn len(param) == limit\n}","sourceCodeStart":371,"sourceCodeEnd":407,"githubUrl":"https://github.com/gofiber/fiber/blob/9a4c7e57fe0b080a04235d28a4b0d2b4b353d58c/constraint.go#L371-L407","documentation":"Error \"len constraint requires an argument\" thrown in gofiber/fiber.","triggerScenarios":"Thrown at constraint.go:389 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"analyzedSha":"9a4c7e57fe0b080a04235d28a4b0d2b4b353d58c","analyzedAt":"2026-08-04T21:44:03.395Z","schemaVersion":2}