返回匿名类型的结果？ [英] Return anonymous type results?

问题描述

使用下面的简单的例子，什么是返回使用LINQ to SQL从多个表结果的最佳方式？

Using the simple example below, what is the best way to return results from multiple tables using Linq to SQL?

说我有两个表：

Dogs:   Name, Age, BreedId
Breeds: BreedId, BreedName

我要与他们的 BreedName 返回所有的狗。我应该使用这样的事情，没有任何问题让所有的狗：

I want to return all dogs with their BreedName. I should get all dogs using something like this with no problems:

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

但是，如果我想与品种的狗，并尝试这个，我有问题：

But if I want dogs with breeds and try this I have problems:

public IQueryable<Dog> 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;
}

现在我认识到，编译器将不会让我回到了一套匿名类型，因为它的预期狗，但有什么办法，而无需创建一个自定义类型返回此？还是我创造我自己的 DogsWithBreedNames 类，并指定在选择这种类型的？还是有另一种更简单的方法？

Now I realize that the compiler won't let me return a set of anonymous types since it's expecting Dogs, but is there a way to return this without having to create a custom type? Or do I have to create my own class for DogsWithBreedNames and specify that type in the select? Or is there another easier way?

推荐答案

我倾向于去这个模式：

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，但它的快速和容易code，易于扩展，可重用性和类型安全的。

It means you have an extra class, but it's quick and easy to code, easily extensible, reusable and type-safe.

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