How to sort by 1 expression or 2 expressions based on a condition?

Question

I show businesses and people in one result and would like to order them together.

pseudo code:

if business name is not null
order by business name
else
order by first name then last name

I built a LINQ query that connects to multiple tables (and works fine) and looks something like this.

var query = from x in ...
    join business in dbContext.Businesses on ...
    from businesses in bus.DefaultIfEmpty()
    join person in dbContext.People on ...
    from people in peo.DefaultIfEmpty()
    select new Party
    {
        person.FirstName,
        person.LastName,
        business.Name,
    };

I can’t understand how to write a LINQ expression that orders ONLY the company name if the record is a business, another person’s first and last name. The closest I can get is the following, which always includes ordering by the person’s name (even for businesses).

var result =
    whereQuery
        .OrderBy(x => x.BusinessName != null ? x.BusinessName : x.PersonFirstName)
        .ThenBy(x => x.PersonLastName);

What converts to SQL:

ORDER BY CASE
    WHEN [business].[Name] IS NOT NULL
    THEN [business].[Name]
    ELSE [person].[FirstName]
END, [person].[LastName]

I would like to:

ORDER BY CASE
    WHEN [business].[Name] IS NOT NULL
    THEN [business].[Name]
    ELSE [person].[FirstName], [person].[LastName]
END

This is what I would like to write (obviously, this is the wrong syntax for the false part):

var result =
        whereQuery
            .OrderBy(x => x.BusinessName != null ? x.BusinessName : x.PersonFirstName, x.PersonLastName);

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Answer 1

var result =
  whereQuery
    .OrderBy(x => x.BusinessName != null ? x.BusinessName : x.PersonFirstName)
    .ThenBy(x => x.BusinessName != null ? x.BusinessName : x.PersonLastName);

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Answer 2

:

var query = from x in ...
    join business in dbContext.Businesses on ...
    from businesses in bus.DefaultIfEmpty()
    join person in dbContext.People on ...
    from people in peo.DefaultIfEmpty()
    select new Party
    {
        Name = business.Name ?? person.FirstName,
        person.LastName
    };

var result = whereQuery
        .OrderBy(x => x.Name)
        .ThenBy(x => x.PersonLastName);

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