How To Create Flutter Moor Relationship With One-To-Many Join - flutter-moor

Question

I have a table Category which is Related to a Task table in a one-to-many relationship and I am attempting to perform a join using Moor.
I would like to return a list for the list of tasks that match a category. How do I do it?
Stream<List<CategoryWithTask>> watchAllCategories() {
return (select(categories)
..orderBy(([
(c) => OrderingTerm(expression: c.name),
])))
.join([leftOuterJoin(tasks, tasks.categoryId.equalsExp(categories.id))])
.watch()
.map((rows) => rows.map(
(row) {
return CategoryWithTask(
category: row.readTable(categories),
task: row.readTable(tasks)); // How do I modify this line to return a list of tasks corresponding to a category?
},
).toList());
}

Answer 1

I managed to find a way with the support of the guys at Flutter Moor after creating an issue on Github. Below is the working code;
Stream<List<CategoryWithTasks>> watchAllCategories() {
return (select(categories)
..orderBy(([
(c) => OrderingTerm(expression: c.name),
])))
.join([leftOuterJoin(tasks, tasks.categoryId.equalsExp(categories.id))])
.watch()
.map((rows) {
final groupedData = <Category, List<Task>>{};
for (final row in rows) {
final category = row.readTable(categories);
final task = row.readTable(tasks);
final list = groupedData.putIfAbsent(category, () => []);
if (task != null) list.add(task);
}
return [
for (final entry in groupedData.entries)
CategoryWithTasks(category: entry.key, tasks: entry.value)
];
});
}