Delete methods: Empty response message

This rule enforces that all Delete RPCs have a response message of google.protobuf.Empty or the resource, as mandated in AIP-135.

Details

This rule looks at any message matching beginning with Delete, and complains if the name of the corresponding output message is not one of:

  • google.protobuf.Empty
  • The name of the RPC with the prefix Delete removed.

It also permits a response of google.longrunning.Operation; in this case, it checks the response_type in the google.longrunning.operation_info annotation and ensures that it corresponds to either google.protobuf.Empty or the name of the RPC with the prefix Delete removed.

Examples

Standard

Incorrect code for this rule:

// Incorrect.
// Should be `google.protobuf.Empty` or the resource.
rpc DeleteBook(DeleteBookRequest) returns (DeleteBookResponse) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/books/*}"
  };
}

Correct code for this rule:

// Correct.
rpc DeleteBook(DeleteBookRequest) returns (google.protobuf.Empty) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/books/*}"
  };
}
// Correct.
rpc DeleteBook(DeleteBookRequest) returns (Book) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/books/*}"
  };
}

Long-running operation

Incorrect code for this rule:

// Incorrect.
rpc DeleteBook(DeleteBookRequest) returns (google.longrunning.Operation) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/books/*}"
  };
  option (google.longrunning.operation_info) = {
    // Should be "google.protobuf.Empty" or "Book".
    response_type: "DeleteBookResponse"
    metadata_type: "DeleteBookMetadata"
  }
}

Correct code for this rule:

// Correct.
rpc DeleteBook(DeleteBookRequest) returns (google.longrunning.Operation) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/books/*}"
  };
  option (google.longrunning.operation_info) = {
    response_type: "google.protobuf.Empty"
    metadata_type: "DeleteBookMetadata"
  }
}
// Correct.
rpc DeleteBook(DeleteBookRequest) returns (google.longrunning.Operation) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/books/*}"
  };
  option (google.longrunning.operation_info) = {
    response_type: "Book"
    metadata_type: "DeleteBookMetadata"
  }
}

Disabling

If you need to violate this rule, use a leading comment above the method. Remember to also include an aip.dev/not-precedent comment explaining why.

// (-- api-linter: core::0135::response-message-name=disabled
//     aip.dev/not-precedent: We need to do this because reasons. --)
rpc DeleteBook(DeleteBookRequest) returns (DeleteBookResponse) {
  option (google.api.http) = {
    delete: "/v1/{book.name=publishers/*/books/*}"
  };
}

If you need to violate this rule for an entire file, place the comment at the top of the file.