C# Appending Linq Queries of Same Type

Question

I have two linq queries that I run on two different tables, Car and Truck. From these queries I select the ID, Name, and Company.

var car = from c in db.Cars
          select new {ID = c.ID, Name = c.Name, Company = c.Company};

var truck = from t in db.Trucks
          select new {ID = t.ID, Name = t.Name, Company = t.Company};

How do I append the truck data to the car data using Linq so that the resultant query contains both car and truck data?

Answer 1

If the resulting types are equivalent, you can use Enumerable.Concat to combine them.

However, I wouldn't normally recommend doing this with anonymous types - instead I'd recommend making a custom class to hold your three (or more) properties. It's possible, given the code above, that the type may be the same post-compilation, but it's impossible to tell for sure without more information.

Personally, I would either use a shared interface (ie: have Car and Truck implement ICompanyInfo with those properties in the interface), and return the car cast into the interface, or make a custom class, and return that from both queries, then use Concat to join them.

Answer 2

Or you could use the Union operator, if they were the same type. This should also work with anonymous types that have the same members:

var vehicles = from c in db.Cars          
    select new {ID = c.ID, Name = c.Name, Company = c.Company};
vehicles.Union(from t in db.Trucks          
    select new {ID = t.ID, Name = t.Name, Company = t.Company};

presuming that the id, name and company types are the same in both car and truck.