{"record":{"id":"4f5ebb0e9f6e8140","repo":"kubernetes/kops","slug":"cannot-parse-field-path-q-w","errorCode":null,"errorMessage":"cannot parse field path %q: %w","messagePattern":"cannot parse field path %q: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"util/pkg/reflectutils/access.go","lineNumber":36,"sourceCode":"\nimport (\n\t\"fmt\"\n\t\"reflect\"\n\t\"strconv\"\n\t\"strings\"\n\t\"time\"\n\n\t\"k8s.io/apimachinery/pkg/api/resource\"\n\tmetav1 \"k8s.io/apimachinery/pkg/apis/meta/v1\"\n\t\"k8s.io/apimachinery/pkg/util/intstr\"\n)\n\nfunc SetString(target interface{}, targetPath string, newValue string) error {\n\ttargetValue := reflect.ValueOf(target)\n\n\ttargetFieldPath, err := ParseFieldPath(targetPath)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"cannot parse field path %q: %w\", targetPath, err)\n\t}\n\n\tfieldSet := false\n\n\tvisitor := func(path *FieldPath, field *reflect.StructField, v reflect.Value) error {\n\t\tif !targetFieldPath.HasPrefixMatch(path) {\n\t\t\treturn nil\n\t\t}\n\n\t\tif targetFieldPath.Matches(path) {\n\t\t\tif !v.CanSet() {\n\t\t\t\treturn fmt.Errorf(\"cannot set field %q (marked immutable)\", path)\n\t\t\t}\n\n\t\t\tif err := setType(v, newValue); err != nil {\n\t\t\t\treturn fmt.Errorf(\"cannot set field %q: %v\", path, err)\n\t\t\t}\n","sourceCodeStart":18,"sourceCodeEnd":54,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/util/pkg/reflectutils/access.go#L18-L54","documentation":"SetString parses the targetPath using ParseFieldPath before applying a value via reflection; this error wraps any parse failure, such as unbalanced brackets, malformed array indices, or invalid path syntax. The underlying parse error is preserved via %w so callers can errors.As/Is it.","triggerScenarios":"Calling reflectutils.SetString(obj, \"spec.metadata.labels[\", \"v\") or otherwise malformed paths — unclosed '[', non-numeric index like spec.subnets[a], or empty path segments.","commonSituations":"kops edit/set-style field overrides (kops set / cluster templates) where a user typos the field path; templating variables that expand to empty or malformed paths; programmatic cluster-field patching with wrong key names.","solutions":["Validate the field path syntax: dot-separated names with bracketed integer indices like spec.kubernetesApiAccess[0]","Print the wrapped cause (`%v` of the error) — it names the exact parse failure position","Test the path against a known-good example, e.g. SetString(&k, \"spec.channel\", \"stable\")"],"exampleFix":"// before\nerr := reflectutils.SetString(cluster, \"spec.subnets[name=us-east]\", \"x\") // unsupported syntax\n// after\nerr := reflectutils.SetString(cluster, \"spec.subnets[0]\", \"x\")","handlingStrategy":"validation","validationCode":"func validFieldPath(p string) bool {\n\tif p == \"\" { return false }\n\t_, err := reflectutils.ParseFieldPath(p)\n\treturn err == nil\n}\n// call: if !validFieldPath(targetPath) { return fmt.Errorf(\"bad field path %q\", targetPath) }","typeGuard":"null","tryCatchPattern":"err := reflectutils.SetString(target, targetPath, val)\nif err != nil {\n\tif strings.Contains(err.Error(), \"cannot parse field path\") {\n\t\treturn fmt.Errorf(\"field path %q is malformed; expected e.g. spec.subnets[0]\", targetPath)\n\t}\n\treturn err\n}","preventionTips":["Pre-validate with ParseFieldPath before SetString","Use canonical examples (spec.channel, spec.subnets[0]) as path templates","Guard template variables so they never expand to empty paths","Reject paths with unbalanced brackets or non-numeric indices early"],"tags":["reflection","path-parsing","validation"],"backgroundTag":"invalid-field-path","analyzedSha":"4c8573c808a73d578c5eadc86d410646ea0b0d73","analyzedAt":"2026-09-05T04:13:19.212Z","contentChangedAt":"2026-09-05T04:13:19.212Z","schemaVersion":2},"datasetVersion":"2026-09-12T07:17:12.445Z"}