In Episerver CMS, how to create a property to display the source URL of an uploaded image or PDF asset (in the Episerver editor interface)?

Question

Annoyingly, the MediaData class in Episerver doesn't have any basic properties like source URL, alt text, etc. I'm trying to implement a class to inherit from MediaData and provide specific properties for a certain type of media asset (PDF in this example).

I've tried manually setting the property values and also overriding the SetDefaultValues event, to no avail. Although, I do see either a textbox or a URL picker based on the type I use for "SrcUrl", however it is blank and never populates the uploaded PDF's URL.

[ContentType(
    DisplayName = "PDF File",
    GUID = "xxxxxxx-xxxx-xxxxxx-xxxx-xxxxxxxxxxx")]
[MediaDescriptor(ExtensionString = "pdf")]
public class PdfFile : MediaData
{
    [UIHint(UIHint.MediaFile)]
    [Display(Name = "PDF URL",
        Description = "Link to view or reference PDF",
        GroupName = SystemTabNames.Content,
        Order = 10)]
    public virtual string SrcUrl
    {
        get { return UrlResolver.Current.GetUrl(this.ContentLink); }
        set { value = UrlResolver.Current.GetUrl(this.ContentLink); }
    }

    // Sets the default property values
    public override void SetDefaultValues(ContentType contentType)
    {
        base.SetDefaultValues(contentType); 

        this.SrcUrl = UrlResolver.Current.GetUrl(this.ContentLink) ?? "Default";
    }
}

****Disclaimer: I'm new to the Episerver CMS and may be missing something stupidly simple (ok with being shamed if appropriate).*

Answer 1

我不确定您需要完成什么，但应该注意的是，在编辑MediaData内容时，可以通过点击发布按钮获取其网址（请注意下载此文件链接）：

编辑：另一个建议是为MediaFile UI提示创建自定义编辑器dijit（使用Dojo）。这样就可以显示URL而无需添加其他属性。

Answer 2

我能够在Epi支持的帮助下解决这个问题，基本上我需要创建一个可初始化的模块 - 这样我就可以进入内容创建所需的生命周期事件。

[InitializableModule]
[ModuleDependency(typeof(InitializationModule))]
public class ModelDefaultValuesInitialization : IInitializableModule
{
    public void Initialize(InitializationEngine context)
    {
        var contentEvents = ServiceLocator.Current.GetInstance<IContentEvents>();
        contentEvents.CreatedContent += MediaBlocksDefaultValues;
    }

    private void MediaBlocksDefaultValues(object sender, ContentEventArgs e)
    {
        PopulateAssetURL(e);
    }

    /// <summary>
    /// Get the URL path of the uploaded asset and set it to the SrcUrl field which is easily visible to editors
    /// </summary>
    /// <param name="e"></param>
    private void PopulateAssetURL(ContentEventArgs e)
    {
        var mediaTypeBlock = e.Content as PdfFile;
        if (mediaTypeBlock != null)
        {
            string result = ServiceLocator.Current.GetInstance<UrlResolver>().GetUrl(mediaTypeBlock.ContentLink);
            if (!string.IsNullOrEmpty(result))
            {
                var srvcLoc = ServiceLocator.Current.GetInstance<IContentRepository>();
                var contentClone = mediaTypeBlock.CreateWritableClone() as PdfFile;
                contentClone.SrcUrl = result;
                srvcLoc.Save(contentClone, SaveAction.Publish, EPiServer.Security.AccessLevel.Administer);
            }
        }            
    }

    public void Uninitialize(InitializationEngine context)
    {
        var contentEvents = ServiceLocator.Current.GetInstance<IContentEvents>();
        contentEvents.CreatedContent -= MediaBlocksDefaultValues;
    }
}

• 注意：我发布上述内容是为了保持一致，但实际上我重构了代码以在名为BaseMediaData的类上设置SrcUrl属性，该类继承自MediaData类。这样，所有文件类型（powerpoint，pdfs等）都可以具有此属性，因为它与所有文件类型相关。图像继承自不同的基类（ImageData），因此我还必须创建一个名为ImageFile的新类，它继承自ImageData并应用相同的属性。我很懒，但是使用一个接口来标准化这两个类的实现可能是一个好主意。