EF核心条件（添加）包括在IQueryable中

Question

在EF6中，我习惯于这样做：

var orders = GetAllEntities().Include(x => x.Contact.User);
if (includeProducts)
{
    orders = orders.Include(x => x.ProductOrders.Select(y => y.RentStockOrders));
    orders = orders.Include(x => x.ProductOrders.Select(y => y.Product));
    orders = orders.Include(x => x.ProductOrders.Select(y => y.Currency));
    orders = orders.Include(x => x.ProductOrders.Select(y => y.Coupons));
    orders = orders.Include(x => x.AdditionalCosts);
    orders = orders.Include(x => x.Partner);
    orders = orders.Include(x => x.OrderCoupons.Select(y => y.Coupon.Partner));
    if (includeStock)
    {
        orders = orders.Include(x => x.ProductOrders.Select(y => y.RentStockOrders.Select(z => z.Stock)));
    }
}
if (includeInvoices)
{
    orders = orders.Include(x => x.Invoices.Select(y => y.Attachments));
}

在EF Core中，无法覆盖，IQueryable因为它更“类型安全”

第一行返回一个IIncludableQueryable<Order, User>，因此当我执行第二个Include时，它想使其有所不同，例如IIncludableQueryable<Ordr,User,ProductOrder>

我主要有一个GetByIdWithCrudRelations包含一组布尔值的集合，用于选择要包含的内容和不包含的内容。有时它只有两个，但是在这种情况下，它只有8个，这意味着如果我需要if-else其他所有功能，它可能会有很多不同的结果。

任何人都有一个聪明的解决方案吗？

Answer 1

您可以使用完全相同的模式。只需从IQueryable<T>变量开始（请注意，IIncludableQueryable<T, P>它仍然IQueryable<T>具有附加ThenInclude支持），然后使用ThenInclude而不是嵌套Selects：

IQueryable<Order> orders = GetAllEntities().Include(x => x.Contact.User);
// or var orders = GetAllEntities().Include(x => x.Contact.User).AsQueryable();
if (includeProducts)
{
    orders = orders.Include(x => x.ProductOrders).ThenInclude(y => y.RentStockOrders);
    orders = orders.Include(x => x.ProductOrders).ThenInclude(y => y.Product);
    orders = orders.Include(x => x.ProductOrders).ThenInclude(y => y.Currency);
    orders = orders.Include(x => x.ProductOrders).ThenInclude(y => y.Coupons);
    orders = orders.Include(x => x.AdditionalCosts);
    orders = orders.Include(x => x.Partner);
    orders = orders.Include(x => x.OrderCoupons).ThenInclude(y => y.Coupon.Partner);
    if (includeStock)
    {
        orders = orders.Include(x => x.ProductOrders).ThenInclude(y => y.RentStockOrders).ThenInclude(z => z.Stock);
    }
}
if (includeInvoices)
{
    orders = orders.Include(x => x.Invoices).ThenInclude(y => y.Attachments);
}

注意，由于ThenInclude链不是嵌套的，也没有必要不同的变量名称x，y，z等-单x或类似的会做同样的。

另外，由于Include正在从根目录重新启动包含链，orders = orders.Include(...)因此可以组合非条件分配，例如

orders = orders
    .Include(x => x.ProductOrders).ThenInclude(y => y.RentStockOrders)
    .Include(x => x.ProductOrders).ThenInclude(y => y.Product)
    .Include(x => x.ProductOrders).ThenInclude(y => y.Currency)
    .Include(x => x.ProductOrders).ThenInclude(y => y.Coupons)
    .Include(x => x.AdditionalCosts)
    .Include(x => x.Partner)
    .Include(x => x.OrderCoupons).ThenInclude(y => y.Coupon.Partner);