example-link-data-collection.md

Implement a link data collection featuring a thumbnail

Inherit LinkData

First, implement a class inheriting from LinkData. Lets call it ThumbnailLinkData.

Since backing data is stored in a Dictionary<string, string> called Attributes. Properties need to read and write from that. This can be achieved by using the various overloads for the method GetAttribute and SetAttribute like illustrated below. Dictionary key resolution and null values are handled behind the scenes.

public class ThumbnailLinkData : LinkData
{
    [Display(Name = "Thumbnail image", Order = 0)]
    [UIHint("image")]
    public virtual ContentReference Thumbnail
    {
        get => GetAttribute((v) => ContentReference.Parse(v));
        set => SetAttribute(value, (v) => v.ToString());
    }

    [Display(Name = "Image description", Order = 10)]
    public virtual string ThumbnailAlt
    {
        get => GetAttribute();
        set => SetAttribute(value);
    }

    [Display(Name = "Image quality", Order = 20)]
    public virtual double ThumbnailQuality
    {
        get => GetAttribute(Convert.ToDouble);
        set => SetAttribute(Convert.ToString(value));
    }

    [Display(Name = "Thumbnail alignment", Order = 30)]
    [SelectOneEnum(typeof(ThumbnailAlign))]
    public virtual ThumbnailAlign Align
    {
        get => GetAttribute(Enum.Parse<ThumbnailAlign>);
        set => SetAttribute(value, v => v.ToString());
    }
}

More details on handling properties and property support can be found here.

Create a property definition

Create a property definition that inherits from PropertyLinkDataCollection using your LinkData implementation as a generic type parameter.

[PropertyDefinitionTypePlugIn(DisplayName = "Link collection with thumbnails", GUID = "9f711ce6-ee75-466c-ab9c-67b65a85abc1")]
public class PropertyThumbnailCollection : PropertyLinkDataCollection<ThumbnailLinkData>
{

}

Define a property on another content model

Define a new property with LinkDataCollection<ThumbnailLinkData> on content. The backing type will resolve automatically.

[CultureSpecific]
[Display(Name = "Thumbnail links", Order = 230)]
public virtual LinkDataCollection<ThumbnailLinkData> Thumbnails { get; set; }

Register type for import/export

In Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddLinkDataExportTransform<ThumbnailLinkData>();
}