# field-comment-defined

Source: https://apigenie.pl/docs/linter/protobuf/rules/field-comment-defined

This rule checks whether every field of a Protobuf file has a leading comment.

## Rule Details

Comments are the documentation of a Protobuf API: `protoc` passes them to the code generators,
which copy them to the generated code, and documentation generators render them.

The `field-comment-defined` rule checks every field, including the fields of oneofs, map fields
and extension fields, and reports `Field '<name>' has no leading comment` when there is no
leading comment, or when it contains only whitespace. A leading comment is the comment right
before the declaration, as `protoc` attaches it: a comment separated from the declaration by a
blank line is a detached comment, and a comment after the declaration on the same line is a
trailing comment; neither counts. Both `//` and `/* */` comments count.

The rule is only part of the `all` ruleset.

## Configuration

This rule has no options.

## Examples

**Good**.

```proto
syntax = "proto3";

package acme.pets.v1;

// A pet that lives in the shelter.
message Pet {
  // The name the shelter gave to the pet.
  string name = 1;
  // Free-form labels, such as the color of the pet.
  map<string, string> labels = 2;
}
```

**Bad**. The linter reports `Field 'labels' has no leading comment`.

```proto
syntax = "proto3";

package acme.pets.v1;

// A pet that lives in the shelter.
message Pet {
  // The name the shelter gave to the pet.
  string name = 1;
  map<string, string> labels = 2; // Free-form labels.
}
```

## When Not to Use It

You may disable this rule if the fields of your files are documented elsewhere, or if their
names are descriptive enough. To exempt the fields of a single message, add an
`// apigenie-lint-disable field-comment-defined` comment to the message.

## Compatibility

This rule is compatible with proto3 files. proto2 and editions files are rejected by the reader
and are not linted.