How do I prevent the conversion of my STRING datatype into INT in sqflite? (flutter) - flutter

Question

onCreate: (db, version) {
// Run the CREATE TABLE statement on the database.
return db.execute(
'CREATE TABLE favourites(id STRING PRIMARY KEY, stop STRING, stop_name STRING, bus STRING)',
);
//id shall consist of both stop and bus numbers
},
This is a segment of my code I used to create the table.
Future<List<Favourite>> getFavourites() async {
// Get a reference to the database.
final db = await database();
// Query the table for all The Dogs.
final List<Map<String, dynamic>> maps = await db.query('favourites');
print('maps line 165: $maps');
// Convert the List<Map<String, dynamic> into a List<Dog>.
return List.generate(maps.length, (i) {
return Favourite(
id: maps[i]['id'],
stop: maps[i]['stop'],
stopName: maps[i]['stopName'],
bus: maps[i]['bus'],
);
});
}
This function above is what I used to retrieve my data. However I got this error instead.
"Unhandled Exception: type 'int' is not a subtype of type 'String'". This means that the numbers that I had inserted into the table as String were converted to int. For example, stop = "09038" would be converted to 9038 as an int.
All my objects were in String.
String id = '0';
String stop = '0';
String stopName = '0';
String bus = '0';
Any solution to this?

Answer 1

There is no STRING data type in SQLite but it is allowed to be used because SQLite allows anything to be used as a data type.
When you define a column as STRING it is actually considered to have NUMERIC affinity as it is described in Determination Of Column Affinity.
From Type Affinity:
A column with NUMERIC affinity may contain values using all five
storage classes. When text data is inserted into a NUMERIC column,
the storage class of the text is converted to INTEGER or REAL (in order
of preference) if the text is a well-formed integer or real literal,
respectively.....
See a simplified demo.
All you have to do is define the columns that you want to behave as strings with the proper data type which is TEXT:
CREATE TABLE favourites(
id TEXT PRIMARY KEY,
stop TEXT,
stop_name TEXT,
bus TEXT
);