How can I select the first child of a child using linq?

Question

I have a set of classes as follows:

public class ResponseWrapper
{
    public IEnumerable<Book> data { get; set; }
}

public class Book
{
    public List<Author> author_data { get; set; }
    public string isbn13 { get; set; }
    public string publisher_name { get; set; }
    public string title { get; set; }        
}

public class Author
{
    public string name { get; set; }
    public string id { get; set; }
}

A Book class contains a list of child Author items. In my case I'm trying to select the 'name' property of the first Author item in the collection.

I thought I'd be able to select it using:

string author = response.data.Where(b => b.author_data.Any()).Select(b => b.author_data.FirstOrDefault().name);

however that won't compile and I think it's because Select returns a collection? Where as I'm just trying to get a single result.

Can anyone tell me the correct linq statement I need to get the single result I'm after?

Thanks

Answer 1

I think you're over-complicating things. You can select the first item just by using First() or FirstOrDefault() .

string author = response.data.First().author_data.First().name;

Just make sure you gaurd for null though.

string author = string.Empty;
Book firstBook = response.data.FirstOrDefault();
if (firstBook != null && firstBook.author_data.Any())
{
    author = firstBook.author_data.First().name;
}

Answer 2

尝试这个

string author = response.data.Where(b => b.author_data.Any()).FirstOrDefault().author_data.FirstOrDefault().name;