Question

//I need to deifne productQuery here
    if (test == true)
    {
      var productQuery = ordersRepository.ProductIn; //it returns IQueryable<ProductIn> type
    }
    else
    {
      var productQuery = ordersRepository.ProductOut; //it returns IQueryable<ProductOut> type
    }

How can I define the productQuery variable?

Thank you!

[EDIT]

dynamic productType;

if (test == true)
    {
      productType = ordersRepository.ProductIn; //it returns IQueryable<ProductIn> type
    }
    else
    {
      productType = ordersRepository.ProductOut; //it returns IQueryable<ProductOut> type
    }

var productQuery = productType as IQueryable<ProductIn>;
if (productQuery == null)
{
     productQuery = productType as IQueryable<ProductIn>;
}

I do this way, is it right way?

Answer 1

You could declare it as a dynamic type, if you’re ok with deferring type resolution until runtime.

dynamic productQuery;
if (test == true)
{
    productQuery = ordersRepository.ProductIn; //it returns IQueryable<ProductIn> type
}
else
{
    productQuery = ordersRepository.ProductOut; //it returns IQueryable<ProductOut> type
}

Your other choice is to declare it as an object type, and then cast it back to the other type as needed.

object productQuery;

if (test == true)
{
    productQuery = ordersRepository.ProductIn; //it returns IQueryable<ProductIn> type
}
else
{
    productQuery = ordersRepository.ProductOut; //it returns IQueryable<ProductOut> type
}

// ... more logic ...
var unboxed = productQuery as IQueryable<ProductIn>;
if (unboxed != null) {
    unboxed.Where( ... and away you go with Linq ...);
}

Update after op’s edit

Let’s say you have a dynamic type productQuery. To use Linq on it, you need to define the types of the delegate. Let’s say that types ProductIn and ProductOut each have a string-type property ProductNo. Then you could write your query like this, again making use of dynamic.

productQuery.Where(new Func<dynamic,bool>(item => item.productNo));

However … I think you could make your life a lot easier by changing your whole approach. You’re clearly working against a common interface for ProductIn and ProductOut, so why not define that explicitly?

public interface IProduct
{
    public string ProductNo { get; set; }
}

public class ProductIn : IProduct { ... }
public class ProductOut : IProduct { ... }

Now your code becomes a lot simpler. Write it like this:

IQueryable<IProduct> productQuery;

if (test == true)
{
    productQuery = ordersRepository.ProductIn; //it returns IQueryable<ProductIn> type
}
else
{
    productQuery = ordersRepository.ProductOut; //it returns IQueryable<ProductOut> type
}

string myResult = productQuery.Where(item => item.productNo == productNo).FirstOrDefault();