AppWrite unable to query by date with dart

Question

I'm dealing with some problems while querying a database hosted on AppWrite in dart. Basically I need to query a date that is save in AppWrite.

final response = await _db.listDocuments(
   databaseId: AppwriteConstants.database_id,
   collectionId: AppwriteConstants.collection_id_events,
   queries: [
      Query.equal('fk_user', fk_user),
      Query.equal('​​date', date.toIso8601String()),
   ],
);

Without the second query Query.equal('date', date.toIso8601String()) the call is fine since it returns all the documents with fk_user = user and in this case the date is returned with the format: 2023-12-15T00:00:00.000+00:00.

While creating a document the date is added in this way:

final response = _db.createDocument(
   databaseId: AppwriteConstants.database_id,
   collectionId: AppwriteConstants.collection_id_events,
   documentId: ..,
   data: {
      ...
      'date': date.toIso8601String(),
      'startTime': startTime.toIso8601String(),
      'endTime': endTime.toIso8601String(),
      ...
   },
);

If I print the date.toIso8601String() it returns: 2023-12-15T00:00:00.000 which differs from what I obtain without the second query on the date which is 2023-12-15T00:00:00.000+00:00. Is this the problem? In the query I also tried to append to date.toIso8601String() the +00:00 but nothing has changed.

Answer 1

In my opinion, Flutter does toIso8601String() a little weird in that the timezone stays in the local timezone. Best practice when working with a remote server is to send data to the server in UTC timezone. So, instead of:

date.toIso8601String()

do

date.toUtc().toIso8601String()

when you create the document or query.

Also, be careful with doing an exact match (Query.equal()) on date times because if the millisecond doesn't match up, the query won't match.