public async Task <Month <T> > GetMonthAsync(int monthId)
{
var(year, month) = MonthUtil.ParseMonthId(monthId);
var values = await MultipleAsync(x =>
x.Year == year && x.MonthId == monthId);
return(new Month <T>(monthId, values));
}
public async Task <Month <INamedBalance> > GetMonthCategoriesAsync(int monthId)
{
var(year, month) = MonthUtil.ParseMonthId(monthId);
var transactions = await MultipleAsync(x =>
x.Year == year && x.MonthId == monthId);
var categories = transactions.GroupBy(x => x.Category)
.Select(g => new CategoryBalance(g.Key, g.Sum(x => x.Amount), monthId));
return(new Month <INamedBalance>(monthId, categories));
}