{"record":{"id":"ac152b235b23a961","repo":"BoundaryML/baml","slug":"failed-to-call-object-constructor","errorCode":null,"errorMessage":"failed to call object constructor","messagePattern":"failed to call object constructor","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"engine/language_client_go/baml_go/raw_objects/utils.go","lineNumber":124,"sourceCode":"func NewRawObject(rt unsafe.Pointer, objectType cffi.BamlObjectType, kwargs []*cffi.HostMapEntry) (any, error) {\n\targs := cffi.BamlObjectConstructorInvocation{\n\t\tType:   objectType,\n\t\tKwargs: kwargs,\n\t}\n\n\tencodedArgs, err := proto.Marshal(&args)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to marshal object constructor arguments: %w\", err)\n\t}\n\tcEncodedArgs := (*C.char)(unsafe.Pointer(&encodedArgs[0]))\n\n\tcBuf := C.WrapCallObjectConstructor(cEncodedArgs, C.uintptr_t(len(encodedArgs)))\n\n\tcontent_bytes := C.GoBytes(unsafe.Pointer(cBuf.ptr), C.int32_t(cBuf.len))\n\tC.WrapFreeBuffer(cBuf) // Free the buffer after use\n\n\tif cBuf.len == 0 {\n\t\treturn nil, fmt.Errorf(\"failed to call object constructor\")\n\t}\n\tif cBuf.ptr == nil {\n\t\treturn nil, fmt.Errorf(\"object constructor returned nil pointer\")\n\t}\n\n\tvar content_holder cffi.InvocationResponse\n\terr = proto.Unmarshal(content_bytes, &content_holder)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to unmarshal content bytes: %w\", err)\n\t}\n\tparsed, err := decodeObjectResponse(rt, &content_holder)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to decode object response: %w\", err)\n\t}\n\n\treturn parsed, nil\n}\n","sourceCodeStart":106,"sourceCodeEnd":142,"githubUrl":"https://github.com/BoundaryML/baml/blob/bd85ce9dee1463ff04d27efd20531013a4ff46c1/engine/language_client_go/baml_go/raw_objects/utils.go#L106-L142","documentation":"After marshaling, NewRawObject invokes WrapCallObjectConstructor in the native runtime, which returns a buffer; this error is raised when that buffer has zero length, meaning the native object-constructor call produced no response. It signals the CFFI call itself failed or returned an empty result rather than a structured error.","triggerScenarios":"WrapCallObjectConstructor returning an empty buffer during NewRawObject (or NewCollector / newMediaFromUrl / newMediaFromBase64 / NewTypeBuilder). This happens when the native runtime rejects or aborts the constructor call without producing a response payload — e.g. an unknown object type or a runtime not properly initialized.","commonSituations":"Mismatch between the Go bindings' object type names and the native runtime's supported types after partial upgrades; calling BAML object APIs before runtime initialization completed; native runtime crash/abort producing an empty buffer.","solutions":["Verify the BAML runtime is fully initialized before constructing raw objects (check init/order of runtime setup).","Confirm the object type string and kwargs match the current BAML API for your version — upgrade Go bindings and native library together.","Check stderr/logs from the native runtime for an abort or panic during the constructor call.","Reduce the call to a minimal reproduction (simple object type, empty kwargs) to isolate whether the runtime itself is broken."],"exampleFix":"// before\nobj, err := NewRawObject(ctx, unknownType, kwargs) // empty response buffer\n\n// after\nif err := bamlRuntime.WaitReady(ctx); err != nil {\n    return fmt.Errorf(\"runtime init: %w\", err)\n}\nobj, err := NewRawObject(ctx, knownSupportedType, kwargs)\nif err != nil {\n    return fmt.Errorf(\"raw object: %w\", err)\n}","handlingStrategy":"try-catch","validationCode":"if err := bamlRuntime.WaitReady(ctx); err != nil {\n    return fmt.Errorf(\"runtime not ready: %w\", err)\n}","typeGuard":"func runtimeReady() bool {\n    return bamlRuntime.State() == ready\n}","tryCatchPattern":"obj, err := NewRawObject(ctx, objectType, kwargs)\nif err != nil && strings.Contains(err.Error(), \"failed to call object constructor\") {\n    return fmt.Errorf(\"native constructor returned no response for %s — verify runtime init and object type: %w\", objectType, err)\n}","preventionTips":["Initialize the BAML runtime fully before any object construction.","Use object type names valid for your installed BAML version.","Upgrade Go bindings and native library together; watch native stderr for aborts."],"tags":["cffi","native-runtime","protobuf","object-construction"],"backgroundTag":"empty-response-body","analyzedSha":"bd85ce9dee1463ff04d27efd20531013a4ff46c1","analyzedAt":"2026-09-12T03:38:25.718Z","contentChangedAt":"2026-09-12T03:38:25.718Z","schemaVersion":2},"datasetVersion":"2026-09-14T11:17:12.474Z"}