go type_error ai_generated true

error: proto: cannot use map field "metadata" with key type string: unsupported key type

ID: go/grpc-protobuf-map-key-type-error

Also available as: JSON · Markdown · 中文
80%Fix Rate
81%Confidence
0Evidence
2024-09-18First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.0 active — — —

Root Cause

The protobuf map field uses an unsupported key type (e.g., float or bytes) in Go generated code.

generic

中文

protobuf映射字段在Go生成的代码中使用了不支持的键类型（例如float或bytes）。

Workarounds

  1. 95% success Use string keys in proto definition. 
    map<string, string> metadata = 1;
  2. 85% success Encode unsupported keys as string with custom encoding. 
    map<string, string> metadata = 1; // encode float as string via strconv.FormatFloat

Dead Ends

Common approaches that don't work:

  1. Change the key type in generated Go code manually. 95% fail

    Regeneration will overwrite manual changes.

  2. Use a repeated field instead of map. 80% fail

    Requires changing the proto schema and all consumers.