[v1.3] Define fields to search on at search-time (`attributesToSearchOn`)

[brunoocasali]

⚠️ This issue is generated, it means the examples and the namings do not necessarily correspond to the language of this repository.
Also, if you are a maintainer, please add any clarification and instructions about this issue.

Sorry if this is already wholly/partially implemented. Feel free to let me know about the state of this issue in the repo.

Related to meilisearch/integration-guides#280

---

This issue is divided into two sections, first, you need to make the implementation, and second, you must update the code-samples (no one likes outdated docs, right?).

New implementation

Related to:

• issue: Define field to search on at search-time meilisearch#3772
• discussion: Define field to search on at search-time product#107 (comment)
• spec: Define fields to search on at runtime  specifications#251

Add support for receiving a new key, attributesToSearchOn (an array of field names), to enable running searches over a subset of searchableAttributes without modifying Meilisearch’s index settings.

Code samples

Inside of this file: .code-samples.meilisearch.yml:

1. Create a new entry with this key search_parameter_guide_attributes_to_search_on_1 containing a call to the search method using the new behavior from the index movies using attributesToSearchOn with an array of one string ["overview"].
   Add a new code sample to the .code-samples.meilisearch.yml file:

Use this as a reference if the previous description was not helpful:

search_parameter_guide_attributes_to_search_on_1: |-
  POST 'http://localhost:7700/indexes/movies/search' 
  with data: { 
    "q": "adventure", "attributesToSearchOn": ["overview"] 
  }   

TODO:

• Add the ability to receive a new param in the search method called attributesToSearchOn.
• Add integration tests
• Update the code-samples accordingly