Get a list of all aliases and union with name

March 13, 2022

Let’s say I have the following entities.

class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
}

class ProductAlias
{
    public int ProductId { get; set; }
    public string Alias { get; set; }
}

Given a product ID, how could I create a list of all aliases for that product that includes the product Name itself in a single query?

I don’t know if I can do something like the following. This syntax doesn’t work because Union() doesn’t take a lambda expression.

DbContext.Products
    .Where(p => p.Id == productId)
    .Select(p => p.Name)
    .Union(p => p.ProductAliases.Select(a => a.Alias))
    .ToList();

>Solution :

Try the following:

var products = DbContext.Products
    .Where(p => p.Id == productId);

products
    .Select(p => p.Name)
    .Union(products.SelectMany(p => p.ProductAliases.Select(a => a.Alias)))
    .ToList();