# field-naming

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

This rule checks whether the name of every field of a Protobuf file is in `lower_snake_case`.

## Rule Details

Code generators derive the accessor names and the JSON names of fields from their Protobuf
names, assuming `lower_snake_case`: `owner_name` becomes `ownerName` in JSON and
`getOwnerName()` in Java. Other conventions produce surprising names, and can make the JSON
names of two fields collide.

The `field-naming` rule checks every field, including the fields of oneofs, map fields and
extension fields, and reports `Field name '<name>' should be lower_snake_case` for every name
that is not in `lower_snake_case`. A name is in `lower_snake_case` when it starts with a
lower-case letter and contains only lower-case letters, digits and single underscores, with no
underscore at the end, such as `owner_name` or `address_2`.

When the name converted to `lower_snake_case` differs from the original and is itself valid, the
message ends with a suggestion, for example `, e.g. '<converted>'`. To convert a name, it is
split into words at underscores and other separators, at lower-to-upper case changes and before
the last capital of an acronym, and the words are joined in lower case with underscores, so
`ownerName` becomes `owner_name` and `HTTPServer` becomes `http_server`.

## Configuration

This rule has no options.

## Examples

**Good**.

```proto
syntax = "proto3";

package acme.pets.v1;

message Pet {
  string owner_name = 1;
  map<string, string> labels = 2;
}
```

**Bad**. The linter reports `Field name 'ownerName' should be lower_snake_case, e.g. 'owner_name'`.

```proto
syntax = "proto3";

package acme.pets.v1;

message Pet {
  string ownerName = 1;
  map<string, string> labels = 2;
}
```

## When Not to Use It

You may disable this rule if the names are part of an existing API that you cannot rename. To
allow a single field, add an `// apigenie-lint-disable field-naming` comment to it.

## Compatibility

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