Filters parameter can not be empty string

[bidoubiwa]

Describe the bug

When trying to do a search with an empty string an error is thrown. The error message is also not really clear.

To Reproduce
Steps to reproduce the behavior:

1. Make a search
2. use filters: "" as a search parameter
3. paf

Error [MeiliSearchApiError]: error parsing filter;  --> 1:1
  |
1 | 
  | ^---
  |
  = expected other

  type: 'MeiliSearchApiError',
  errorCode: 'invalid_filter',
  errorType: 'invalid_request_error',
  errorLink: 'https://docs.meilisearch.com/errors#invalid_filter',
  httpStatus: 400

Expected behavior
Ignore the empty filter as no filter is still a filter.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: IOS
• meilisearch: v0.20

[bidoubiwa]

$ curl -X POST http://localhost:7700/indexes/indexUID/search --data '{ "q": "", "filters": "" }'
{"message":"error parsing filter;  --> 1:1\n  |\n1 | \n  | ^---\n  |\n  = expected other","errorCode":"invalid_filter","errorType":"invalid_request_error","errorLink":"https://docs.meilisearch.com/errors#invalid_filter"}⏎

MeiliSearch version: 0.20.0

[curquiza]

Checked with @gmourier
It put it as good_first_issue. The expected behavior: not return an error and do not apply any filter.
A test should be added.

This will be fixed in next versions

[curquiza]

Fixed in v0.25.0rc0

Test:

• add:

[
  { "id": 2,    "title": "Pride and Prejudice",                    "author": "Jane Austin",              "genre": "romance",    "price": 3.5 },
  { "id": 456,  "title": "Le Petit Prince",                        "author": "Antoine de Saint-Exupéry", "genre": "adventure" , "price": 10.0 },
  { "id": 1,    "title": "Alice In Wonderland",                    "author": "Lewis Carroll",            "genre": "fantasy",    "price": 25.99 },
  { "id": 1344, "title": "The Hobbit",                             "author": "J. R. R. Tolkien",         "genre": "fantasy" },
  { "id": 4,    "title": "Harry Potter and the Half-Blood Prince", "author": "J. K. Rowling",            "genre": "fantasy" },
  { "id": 42,   "title": "The Hitchhiker's Guide to the Galaxy",   "author": "Douglas Adams" }
]

• add filterable attributes
• search

{
    "q": "",
    "filter": ""
}

{
    "hits": [],
    "nbHits": 0,
    "exhaustiveNbHits": false,
    "query": "",
    "limit": 20,
    "offset": 0,
    "processingTimeMs": 2
}

[bidoubiwa]

An empty filter gives returns no hits? Since there is no filter condition in the string, it should not apply any filter.

With the same logic, an empty query should also return no documents.

Also implementation wise, if you create dynamically your filters you'll have to check if filter === "" and then remove the
filter field of your query parameter.

Maybe I should answer to that in the related specification?

[curquiza]

Discussion about what we need to do here meilisearch/milli#422