如何使用 EF 从导航属性中仅选择特定列

Question

I'm trying to select only 2 columns from the navigation properties but unable to do it, can anyone let me know how can I achieve this?

It works good default way(selecting all columns) :

  var productreceipts = db.productreceipts.Include(p => p.employee).Include(p => p.productmaster).Include(p => p.vendor);

What I want:

Select only 2 columns form each of employee, productmaster, vendor tables.

I know how to select if I have only one table:

var productreceipt = db.productreceipts.Select(p => new { p.ReceiptId, p.ReceivedBy });

EDIT : I want to select all properties of first table(productreceipts) and only a few selected from others.

Any help will be much appreciated.

Thanks in advance.

Answer 1

You can use like :

  var productreceipts = db.productreceipts.Include(p => p.employee).
                                          .Select(p => new { propertyName = p.productmaster.SomeProperty })

Answer 2

Try this:

var productreceipt = db.productreceipts
    .Select(p => 
    new {   productreceipts_prop_1 = p.productreceipts_prop_1,
            productreceipts_prop_2 = p.productreceipts_prop_2,
            productreceipts_prop_3 = p.productreceipts_prop_3,
            productreceipts_prop_4 = p.productreceipts_prop_4,

            employee_prop_1 = p.employee.employee_prop_1,
            employee_prop_2 = p.employee.employee_prop_2,

            productmaster_prop_1 = p.productmaster.productmaster_prop_1,
            productmaster_prop_2 = p.productmaster.productmaster_prop_2,

            vendor_prop_1 = p.vendor.vendor_prop_1,
            vendor_prop_1 = p.vendor.vendor_prop_1,
    });

EDIT:

There is no need to use the .Include() You can directly use the navigator property to retrieve the data.

Answer 3

If you have lazy loading enabled then you can directly use

.Select(p => new { ProductId = p.productmaster.ProductId }

else you will have to take inner join and select individual columns in single select.