Summary

This PR adds a new dedicated route /indexes/{indexUID}/fields that returns a complete list of all field names in an index, including nested fields. This provides a lightweight alternative to the stats route for clients that only need field information without the overhead of field distribution calculations.

Changes Made

1. Route Details

• Endpoint: GET /indexes/{indexUid}/fields
• Response: Array of strings containing all field names (e.g., ["id", "title", "user.name", "user.email"])
• Authentication: Requires indexes.get permission
• Error Handling: Returns 404 for non-existent indexes with proper error format

2. Implementation Details

• Uses FieldsIdsMap::names() to get all field names including nested fields
• Returns field names in dot notation format (e.g., user.profile.age)
• No performance impact on indexing as it only reads existing field metadata
• Includes both top-level and deeply nested fields

3. Testing

• Added fields() method to test utilities in crates/meilisearch/tests/common/index.rs
• Added comprehensive test suite in crates/meilisearch/tests/index/stats.rs:
  • Basic functionality test with simple nested fields
  • Complex nested fields test with up to 6 levels of nesting
  • Error handling test for non-existent indexes
  • Verification of field name format and uniqueness

Example Usage

# Get all fields from an index
GET /indexes/movies/fields

# Response
[
  "id",
  "title", 
  "user.name",
  "user.email",
  "metadata.category",
  "metadata.author.name"
]

Breaking Changes

None - this is a new route that doesn't affect existing functionality.
no db change