Query Params Do Not Support Multiple Filters on the Same Key (e.g. `created_at=gte...&created_at=lte...`)

[putheng]

Description:

I'm encountering an issue where query parameters do not support multiple filters on the same key when using array values. For example, filtering with:

created_at=gte.2025-04-03&created_at=lte.2025-04-05

is a common pattern in PostgREST to filter by a range, but the library currently fails to handle this correctly.

---

Reproduction Code:

ref.expenseEntities.findAll(params: {
  'created_at': ['gte.2025-04-03', 'lte.2025-04-05']
});

Decoded URL:

created_at=[gte.2025-04-03,+lte.2025-04-05]

---

Error from PostgREST:

unhandled Exception: DataException: 
{
  code: PGRST100,
  details: unexpected "[" expecting "not" or operator (eq, gt, ...),
  message: "failed to parse filter ([gte.2025-04-03, lte.2025-04-05])"
}

---

Temporary Workaround:

I resolved this by manually constructing the URI to ensure repeated keys are supported:

final parseUri = Uri.parse(baseUrl);
final uri = parseUri.replace(
  path: '${parseUri.path}/${urlForFindAll(params)}'.replaceAll('//', '/'),
  queryParameters: params,
);
sendRequest<List<T>>(
  uri,
  method: methodForFindAll(params),
  headers: headers,
  label: label,
);

This works for now, but it feels like a workaround rather than a clean solution. Ideally, the library should support multiple filters for the same key in a proper way compatible with PostgREST.

---

Expected Behavior:

The library should generate query strings with repeated keys when array values are provided in the params, like:

...?created_at=gte.2025-04-03&created_at=lte.2025-04-05

---

Additional Notes:

Let me know if I’m missing a proper way to handle this use case within the current API. Otherwise, I hope this can be improved in a future release!