static void Main(string[] args)
{
var nwind = new NorthwindContext();
var loggerFactory = (nwind as IInfrastructure<IServiceProvider>).GetService<ILoggerFactory>();
loggerFactory.AddConsole(LogLevel.Verbose);
Submission2.GroupWithLet(nwind);
}
public static void GroupByNestedProp(NorthwindContext nwind)
{
// BUG throws "Sequence contains more than one element"
var q = from p in nwind.Products
group p by p.Category.CategoryName;
q.ToArray();
}
public static void GroupWithLet(NorthwindContext nwind)
{
// BUG throws "Expression of type '...' cannot be used for parameter of type '...' of method '...'"
var q = from p in nwind.Products
let cat = p.CategoryID
group p by cat;
// group p by p.CategoryID; // - also fails when 'let' is present
q.ToArray();
}
public static void GroupingAndNavigationWhere(NorthwindContext nwind)
{
// INFO "Support translating of GroupBy() to SQL" https://github.com/aspnet/EntityFramework/issues/2341
// INFO "GroupBy throws NRE when grouping using navigation properties" https://github.com/aspnet/EntityFramework/issues/3626
// BUG throws "Expression of type '...' cannot be used for parameter of type '...'
var q = from o in nwind.Orders
where o.Shipper.CompanyName == "Speedy Express"
group o by o.OrderDate;
q.ToArray();
}
public static void DateConst(NorthwindContext nwind)
{
var dataParam = Expression.Parameter(typeof(IQueryable<Order>), "data");
var itemParam = Expression.Parameter(typeof(Order), "i");
Expression query = dataParam;
var whereClause = Expression.Lambda(
Expression.MakeBinary(
ExpressionType.Equal,
Expression.PropertyOrField(Expression.PropertyOrField(itemParam, "OrderDate"), "Value"),
Expression.Constant(new DateTime(1998, 5, 6))
),
itemParam
);
query = Expression.Call(typeof(Queryable), "Where", new[] { typeof(Order) }, query, whereClause);
query = Expression.Call(typeof(Queryable), "Count", new[] { typeof(Order) }, query);
Expression.Lambda(query, dataParam).Compile().DynamicInvoke(nwind.Orders);
}