String only format

This rule enforces that the following format specifiers are used only on fields of type string, as mandated by AIP-202:

• UUID4
• IPV4
• IPV6
• IPV4_OR_IPV6

Details

This rule looks at every non-string field with a (google.api.field_info).format and complains if the format specifier is one meant only for use on string fields.

Examples

Incorrect code for this rule:

message Book {
  string name = 1;

  // Incorrect. Non-string must not be assigned format UUID4.
  int32 edition = 2 [(google.api.field_info).format = UUID4];
}

Correct code for this rule:

message Book {
  string name = 1;

  int32 edition = 2;

  // This is a correct example of a string-only format
  // on a string field.
  string uid = 3 [(google.api.field_info).format = UUID4];
}

Disabling

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

message Book {
  string name = 1;

  // (-- api-linter: core::0202::string-only-format=disabled
  //     aip.dev/not-precedent: We need to do this because reasons. --)
  int32 edition = 2 [(google.api.field_info).format = UUID4];
}

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