Singletons: Forbidden methods

This rule enforces that singleton resources do not define Create, or Delete methods, as mandated in AIP-156.

Details

This rule looks at any message with a name variable in the URI where the name ends in anything other than *. It assumes that this is a method operating on a singleton resource, and complains if the method is a Create, or Delete standard method.

Examples

Incorrect code for this rule:

// Incorrect.
rpc GetSettings(GetSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    get: "/v1/{name=publishers/*/settings}"
  };
}

rpc UpdateSettings(UpdateSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    patch: "/v1/{settings.name=publishers/*/settings}"
    body: "settings"
  };
}

// This method should not exist. The settings should be implicitly created
// when the publisher is created.
rpc CreateSettings(CreateSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    post: "/v1/{name=publishers/*/settings}"
    body: "settings"
  };
}

// This method should not exist. The settings should always implicitly exist.
rpc DeleteSettings(DeleteSettingsRequest) returns (google.protobuf.Empty) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/settings}"
  };
}

Correct code for this rule:

// Correct.
rpc GetSettings(GetSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    get: "/v1/{name=publishers/*/settings}"
  };
}

rpc UpdateSettings(UpdateSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    patch: "/v1/{settings.name=publishers/*/settings}"
    body: "settings"
  };
}

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.

rpc GetSettings(GetSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    get: "/v1/{name=publishers/*/settings}"
  };
}

rpc UpdateSettings(UpdateSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    patch: "/v1/{settings.name=publishers/*/settings}"
    body: "settings"
  };
}

// (-- api-linter: core::0156::forbidden-methods=disabled
//     aip.dev/not-precedent: We need to do this because reasons. --)
rpc CreateSettings(CreateSettingsRequest) returns (Settings) {
  option (google.api.http) = {
    post: "/v1/{name=publishers/*/settings}"
    body: "settings"
  };
}

// (-- api-linter: core::0156::forbidden-methods=disabled
//     aip.dev/not-precedent: We need to do this because reasons. --)
rpc DeleteSettings(DeleteSettingsRequest) returns (google.protobuf.Empty) {
  option (google.api.http) = {
    delete: "/v1/{name=publishers/*/settings}"
  };
}

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