{"record":{"id":"0b3cdf3ee748ba53","repo":"derailed/k9s","slug":"expected-unstructured-but-got-t-0b3cdf","errorCode":null,"errorMessage":"expected Unstructured, but got %T","messagePattern":"expected Unstructured, but got %T","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"internal/render/sts.go","lineNumber":45,"sourceCode":"\tmodel1.HeaderColumn{Name: \"VALID\", Attrs: model1.Attrs{Wide: true}},\n\tmodel1.HeaderColumn{Name: \"AGE\", Attrs: model1.Attrs{Time: true}},\n}\n\n// StatefulSet renders a K8s StatefulSet to screen.\ntype StatefulSet struct {\n\tBase\n}\n\n// Header returns a header row.\nfunc (s StatefulSet) Header(_ string) model1.Header {\n\treturn s.doHeader(defaultSTSHeader)\n}\n\n// Render renders a K8s resource to screen.\nfunc (s StatefulSet) Render(o any, _ string, row *model1.Row) error {\n\traw, ok := o.(*unstructured.Unstructured)\n\tif !ok {\n\t\treturn fmt.Errorf(\"expected Unstructured, but got %T\", o)\n\t}\n\tif err := s.defaultRow(raw, row); err != nil {\n\t\treturn err\n\t}\n\tif s.specs.isEmpty() {\n\t\treturn nil\n\t}\n\tcols, err := s.specs.realize(raw, defaultSTSHeader, row)\n\tcols.hydrateRow(row)\n\n\treturn err\n}\n\nfunc (s StatefulSet) defaultRow(raw *unstructured.Unstructured, r *model1.Row) error {\n\tvar sts appsv1.StatefulSet\n\terr := runtime.DefaultUnstructuredConverter.FromUnstructured(raw.Object, &sts)\n\tif err != nil {\n\t\treturn err","sourceCodeStart":27,"sourceCodeEnd":63,"githubUrl":"https://github.com/derailed/k9s/blob/2d3ccc6ba2ce98c3781bfc441bb3e884f072774f/internal/render/sts.go#L27-L63","documentation":"StatefulSet.Render implements the k9s renderer contract for statefulset rows: the object must be *unstructured.Unstructured so defaultRow can fill base columns and the custom-column engine (s.specs.realize against defaultSTSHeader) can walk the raw JSON. The comma-ok assertion fails and returns this error, printing the concrete %T, when any other Go type reaches the renderer — a wiring bug in the caller.","triggerScenarios":"Calling StatefulSet{}.Render with a typed *appsv1.StatefulSet, a map[string]any, a value unstructured.Unstructured, or a synthetic row type; binding the sts renderer to a different GVR in a custom view factory.","commonSituations":"Writing k9s plugins or custom views that register renderers per GVR; refactoring a workload view to feed typed client-go objects; unit tests with typed fixtures.","solutions":["Pass the informer-cached object untouched as *unstructured.Unstructured","Convert typed objects with runtime.DefaultUnstructuredConverter.ToUnstructured and wrap in &unstructured.Unstructured{Object: m}","Verify the view factory binds StatefulSet only to the STS GVR","Guard custom call sites with a comma-ok check and skip the row on mismatch"],"exampleFix":"// before\ntyped := &appsv1.StatefulSet{}\nerr := stsRenderer.Render(typed, ns, row)\n// after\nm, _ := runtime.DefaultUnstructuredConverter.ToUnstructured(typed)\nerr := stsRenderer.Render(&unstructured.Unstructured{Object: m}, ns, row)","handlingStrategy":"type-guard","validationCode":"// gate before invoking the StatefulSet renderer\nif _, ok := o.(*unstructured.Unstructured); !ok {\n\treturn fmt.Errorf(\"sts view requires *unstructured.Unstructured, got %T\", o)\n}\nerr := stsRenderer.Render(o, ns, row)","typeGuard":"func isUnstructured(o any) bool {\n\t_, ok := o.(*unstructured.Unstructured)\n\treturn ok\n}","tryCatchPattern":"if err := stsRenderer.Render(o, ns, row); err != nil {\n\tslog.Warn(\"sts row skipped\", \"type\", fmt.Sprintf(\"%T\", o), slogs.Error, err)\n\treturn nil // drop the row, keep the view alive\n}","preventionTips":["Register each renderer with exactly one GVR in the view factory","Deliver informer-cache objects to Render untouched as *unstructured.Unstructured","Convert typed objects with runtime.DefaultUnstructuredConverter before rendering","Unit-test Render with the exact asserted type (pointer, not value)"],"tags":["kubernetes","go","type-assertion","workloads","statefulset","renderer","k9s"],"backgroundTag":null,"analyzedSha":"2d3ccc6ba2ce98c3781bfc441bb3e884f072774f","analyzedAt":"2026-08-15T16:09:14.432Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}