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Slightly More Complex Example

To execute this example, see LinkIt.Samples.

Let's say you have a blog post class that references media, images and tags by IDs.

Visualization

public class BlogPost {
    public int Id { get; set; }
    public string Title { get; set; }
    public List<int> TagIds { get; set; }
    public Author Author { get; set; }
    public MultimediaContentReference MultimediaContentRef { get; set; }
}

public class Author {
    public string Name { get; set; }
    public string Email { get; set; }
    public string ImageId { get; set; }
}

public class MultimediaContentReference {
    public string Type { get; set; }
    public object Id { get; set; }
}

public class Image {
    public string Id { get; set; }
    public string Credits { get; set; }
    public string Url { get; set; }
}

The model and linked source for media and tags are defined in the getting started example.

The linked source representing a blog post with its media, images and tags would be defined like this:

public class BlogPostLinkedSource : ILinkedSource<BlogPost> {
    public BlogPost Model { get; set; }
    public List<Tag> Tags { get; set; }
    public AuthorLinkedSource Author { get; set; }
    public object MultimediaContent { get; set; }
}

public class AuthorLinkedSource : ILinkedSource<Author> {
    public Author Model { get; set; }
    public Image Image { get; set; }
}

LoadLinkProtocol

Most of the load link protocol can be defined using the default conventions.

  • BlogPostLinkedSource/Tags will match BlogPost/TagIds
  • BlogPostLinkedSource/Author will match BlogPost/Author
  • AuthorLinkedSource/Image will match Author/ImageId

The BlogPost object owns a nested object of type Author. In order to load link the author with its own linked image, we need to add the link target BlogPostLinkedSource/Author as a nested linked source of type AuthorLinkedSource.

Polymorphism

For the linked target BlogPostLinkedSource/MultimediaContent, we need to configure the load link protocol since none of the default conventions applies. Moreover, it is a special configuration since it involves some polymorphism.

public class BlogPostLinkedSourceConfig : ILoadLinkProtocolConfig {
    public void ConfigureLoadLinkProtocol(LoadLinkProtocolBuilder loadLinkProtocolBuilder) {
        loadLinkProtocolBuilder.For<BlogPostLinkedSource>()
            .PolymorphicLoadLink(
                linkedSource => linkedSource.Model.MultimediaContentRef,
                linkedSource => linkedSource.MultimediaContent,
                link => link.Type,
                includes => includes
                    .Include<MediaLinkedSource>().AsNestedLinkedSourceById(
                        "media",
                        link => (int)link.Id
                    )
                    .Include<Image>().AsReferenceById(
                        "image",
                        link => (string)link.Id
                    )
            );
    }
}

If MultimediaContentRef.Type is "image", then an image will be loaded and linked; however, if MultimediaContentRef.Type is "media", a media along with its tags will be loaded and linked. Here, we are reusing MediaLinkedSource as defined in the Getting Started example.

Usage

Load link by ID

var actual = loadLinkProtocol.LoadLink<BlogPostLinkedSource>().ById(1);

Load link by IDs

var actual = _loadLinkProtocol.LoadLink<BlogPostLinkedSource>().ByIds(
    new List<int>{3,2,1}
);

Load link query

var models = GetBlogPostByKeyword("fish");
var actual = _loadLinkProtocol.LoadLink<BlogPostLinkedSource>().FromModels(models);

Load link transient model (not in a data source)

var model = new BlogPost {
    Id = 101,
    Author = new Author{
        Name = "author-name-101",
        Email = "author-email-101",
        ImageId = "distinc-id-loaded-once", //same entity referenced twice
    },
    MultimediaContentRef = new MultimediaContentReference{
        Type = "image",
        Id = "distinc-id-loaded-once" //same entity referenced twice
    },
    TagIds = new List<int>{
        1001,
        1002
    },
    Title = "Title-101"
};

var actual = _loadLinkProtocol.LoadLink<BlogPostLinkedSource>().FromModel(model);

Read more

See also