LINQ Join with Nullable Foreign Keys - Unexpected Null Results in C# 9
Could someone explain I've looked through the documentation and I'm still confused about I'm working on a project using Entity Framework Core 5.0 and I'm trying to perform a join between two tables - `Orders` and `Customers`... The `Orders` table has a nullable foreign key for `CustomerId`, and I want to retrieve all orders along with their corresponding customer details, even if the `CustomerId` is null. Here's the query I wrote: ```csharp var query = from order in context.Orders join customer in context.Customers on order.CustomerId equals customer.Id into custGroup from cust in custGroup.DefaultIfEmpty() select new { OrderId = order.Id, OrderDate = order.OrderDate, CustomerName = cust != null ? cust.Name : "No Customer" }; ``` However, I'm getting unexpected behavior. When I run this query, I notice that if `CustomerId` is null, the `CustomerName` is coming back as null instead of "No Customer" as intended. Here’s the result output for some orders: | OrderId | OrderDate | CustomerName | |---------|------------|--------------| | 1 | 2023-10-01 | John Doe | | 2 | 2023-10-02 | (null) | | 3 | 2023-10-03 | No Customer | I've also tried using a method syntax version of the LINQ query: ```csharp var query = context.Orders .GroupJoin(context.Customers, o => o.CustomerId, c => c.Id, (o, cGroup) => new { o, cGroup }) .SelectMany(x => x.cGroup.DefaultIfEmpty(), (x, c) => new { OrderId = x.o.Id, OrderDate = x.o.OrderDate, CustomerName = c != null ? c.Name : "No Customer" }); ``` But I still get the same null values for `CustomerName` when `CustomerId` is missing. Any insights on why this is happening, or how I can fix this issue to ensure I get the desired "No Customer" string instead of null? Thanks in advance! My development environment is Linux. Is there a better approach? For context: I'm using C# on Ubuntu 20.04. My team is using C# for this CLI tool.