现在我意识到编译器不让我返回一组匿名类型，因为它期待狗，但有没有一种方法来返回这个而不必创建一个自定义类型?

使用Use对象可返回匿名类型列表，而无需创建自定义类型。 这将在没有编译器错误的情况下工作(在。net 4.0中)。我将列表返回给客户端，然后在JavaScript上解析它:

public object GetDogsWithBreedNames()
{
    var db = new DogDataContext(ConnectString);
    var result = from d in db.Dogs
                 join b in db.Breeds on d.BreedId equals b.BreedId
                 select new
                        {
                            Name = d.Name,
                            BreedName = b.BreedName
                        };
    return result;
}

我倾向于这样的模式:

public class DogWithBreed
{
    public Dog Dog { get; set; }
    public string BreedName  { get; set; }
}

public IQueryable<DogWithBreed> GetDogsWithBreedNames()
{
    var db = new DogDataContext(ConnectString);
    var result = from d in db.Dogs
                 join b in db.Breeds on d.BreedId equals b.BreedId
                 select new DogWithBreed()
                        {
                            Dog = d,
                            BreedName = b.BreedName
                        };
    return result;
}

这意味着你有一个额外的类，但它是快速和容易编码，易于扩展，可重用和类型安全。

在c# 7中你现在可以使用元组了!这样就不需要为了返回结果而创建一个类。

下面是一个示例代码:

public List<(string Name, string BreedName)> GetDogsWithBreedNames()
{
    var db = new DogDataContext(ConnectString);
    var result = from d in db.Dogs
             join b in db.Breeds on d.BreedId equals b.BreedId
             select new
             {
                Name = d.Name,
                BreedName = b.BreedName
             }.ToList();

    return result.Select(r => (r.Name, r.BreedName)).ToList();
}

您可能需要安装System。ValueTuple nuget包。

如果你要归还《Dogs》，你应该这样做:

public IQueryable<Dog> GetDogsWithBreedNames()
{
    var db = new DogDataContext(ConnectString);
    return from d in db.Dogs
           join b in db.Breeds on d.BreedId equals b.BreedId
           select d;
}

如果您希望Breed立即加载而不是延迟加载，只需使用适当的DataLoadOptions构造。

只需要选择狗，然后使用dog.Breed。BreedName，这应该可以正常工作。

如果你有很多狗，使用DataLoadOptions。LoadWith来减少db调用的数量。

BreedId in the Dog table is obviously a foreign key to the corresponding row in the Breed table. If you've got your database set up properly, LINQ to SQL should automatically create an association between the two tables. The resulting Dog class will have a Breed property, and the Breed class should have a Dogs collection. Setting it up this way, you can still return IEnumerable<Dog>, which is an object that includes the breed property. The only caveat is that you need to preload the breed object along with dog objects in the query so they can be accessed after the data context has been disposed, and (as another poster has suggested) execute a method on the collection that will cause the query to be performed immediately (ToArray in this case):

public IEnumerable<Dog> GetDogs()
{
    using (var db = new DogDataContext(ConnectString))
    {
        db.LoadOptions.LoadWith<Dog>(i => i.Breed);
        return db.Dogs.ToArray();
    }

}

然后，访问每只狗的品种是微不足道的:

foreach (var dog in GetDogs())
{
    Console.WriteLine("Dog's Name: {0}", dog.Name);
    Console.WriteLine("Dog's Breed: {0}", dog.Breed.Name);        
}