Custom methods: HTTP parent variable

This rule enforces that custom methods only use the parent variable if the RPC noun matches the resource, as mandated in AIP-136.

Details

This rule looks at custom methods and, if the URI contains a parent variable, it ensures that the RPC name ends with the same text as the final component in the URI (after adjusting for case).

Examples

Incorrect code for this rule:

// Incorrect.
// The variable should be "book", or the RPC name should change.
rpc WritePage(WritePageRequest) return (WritePageResponse) {
  option (google.api.http) = {
    post: "/v1/{parent=publishers/*/books/*}:writePage"
    body: "*"
  };
}

Correct code for this rule:

// Correct.
// If Page is not a first-class resource, use `book` as the variable name
// and a verb-noun suffix.
rpc WritePage(WritePageRequest) return (WritePageResponse) {
  option (google.api.http) = {
    post: "/v1/{book=publishers/*/books/*}:writePage"
    body: "*"
  };
}
// Correct.
// If Page is a first-class, not-yet-created resource, use `parent` as the
// variable name and a verb-only suffix.
rpc WritePage(WritePageRequest) return (WritePageResponse) {
  option (google.api.http) = {
    post: "/v1/{parent=publishers/*/books/*}/pages:write"
    body: "*"
  };
}

See also the http-name-variable rule (for first-class resources that are already created).

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::0136::http-parent-variable=disabled
//     aip.dev/not-precedent: We need to do this because reasons. --)
rpc WritePage(WritePageRequest) return (WritePageResponse) {
  option (google.api.http) = {
    post: "/v1/{parent=publishers/*/books/*}:writePage"
    body: "*"
  };
}

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