Selectors for page builder components

        // Assigns a selector component to the 'Images' property
        [EditingComponent(MediaFilesSelector.IDENTIFIER)]
        // Configures the media library from which you can select files in the selector
        [EditingComponentProperty(nameof(MediaFilesSelectorProperties.LibraryName), "Graphics")]
        // Limits the maximum number of files that can be selected at once
        [EditingComponentProperty(nameof(MediaFilesSelectorProperties.MaxFilesLimit), 5)]
        // Configures the allowed file extensions for the selected files
        [EditingComponentProperty(nameof(MediaFilesSelectorProperties.AllowedExtensions), ".gif;.png;.jpg;.jpeg")]
        // Returns a list of media files selector items (objects that contain the GUIDs of selected media files)
        public IEnumerable<MediaFilesSelectorItem> Images { get; set; } = Enumerable.Empty<MediaFilesSelectorItem>();

        private readonly IMediaFileInfoProvider mediaFileInfo;
        private readonly IComponentPropertiesRetriever componentPropertiesRetriever;
        private readonly ISiteService siteService;

        public MediaFilesSelectorExample(IMediaFileInfoProvider mediaFileInfo, 
                                         IComponentPropertiesRetriever componentPropertiesRetriever,
                                         ISiteService siteService)
        {
            this.mediaFileInfo = mediaFileInfo;
            this.componentPropertiesRetriever = componentPropertiesRetriever;
            this.siteService = siteService;
        }

        public ActionResult Index()
        {
            // Retrieves the GUID of the first selected media file from the 'Images' property
            Guid guid = componentPropertiesRetriever.Retrieve<CustomWidgetProperties>().Images.FirstOrDefault()?.FileGuid ?? Guid.Empty;
            // Retrieves the MediaFileInfo object that corresponds to the selected media file GUID
            MediaFileInfo mediaFile = mediaFileInfo.Get(guid, siteService.CurrentSite.SiteID);

            string url = String.Empty;
            if (mediaFile != null)
            {
                // Retrieves an URL of the selected media file
                url = MediaLibraryHelper.GetDirectUrl(mediaFile);
            }

            // Custom logic...

            return View();
        }

<!-- Scopes the maximum file size configuration to only affect files uploaded using the media files selector -->
<location path="Kentico.Uploaders">
  <system.webServer>
    <security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="MAXSIZE_IN_BYTES" />
      </requestFiltering>
    </security>
  </system.webServer>
  <system.web>
    <httpRuntime maxRequestLength="MAXSIZE_IN_KILOBYTES" executionTimeout="NUMBER_IN_SECONDS" />
  </system.web>
</location> 

        // Assigns a selector component to the Pages property
        [EditingComponent(PageSelector.IDENTIFIER)]
        // Limits the selection of pages to a subtree rooted at the 'Products' page
        [EditingComponentProperty(nameof(PageSelectorProperties.RootPath), "/Products")]
        // Sets an unlimited number of selectable pages
        [EditingComponentProperty(nameof(PageSelectorProperties.MaxPagesLimit), 0)]
        // Returns a list of page selector items (node GUIDs)
        public IEnumerable<PageSelectorItem> Pages { get; set; } = Enumerable.Empty<PageSelectorItem>();

        // Assigns a selector component to the 'PagePaths' property
        [EditingComponent(PathSelector.IDENTIFIER)]
        // Limits the selection of pages to a subtree rooted at the 'Products' page
        [EditingComponentProperty(nameof(PathSelectorProperties.RootPath), "/Products")]
        // Sets the maximum number of selected pages to 6
        [EditingComponentProperty(nameof(PathSelectorProperties.MaxPagesLimit), 6)]
        // Returns a list of path selector items (page paths)
        public IEnumerable<PathSelectorItem> PagePaths { get; set; } = Enumerable.Empty<PathSelectorItem>();

        // Assigns a selector component to the 'Attachments' property
        [EditingComponent(AttachmentSelector.IDENTIFIER)]
        // Limits the maximum number of attachments that can be selected at once
        [EditingComponentProperty(nameof(AttachmentSelectorProperties.MaxFilesLimit), 3)]
        // Configures the allowed file extensions for the selected attachments
        [EditingComponentProperty(nameof(AttachmentSelectorProperties.AllowedExtensions), ".gif;.png;.jpg;.jpeg")]
        // Returns a list of attachment selector items (attachment objects)
        public IEnumerable<AttachmentSelectorItem> Attachments { get; set; } = Enumerable.Empty<AttachmentSelectorItem>();

        private readonly IComponentPropertiesRetriever propertiesRetriever;
        private readonly ISiteService siteService;
        private readonly IPageAttachmentUrlRetriever attachmentUrlRetriever;

        public AttachmentSelectorExample(IComponentPropertiesRetriever propertiesRetriever,
                                         ISiteService siteService,
                                         IPageAttachmentUrlRetriever attachmentUrlRetriever)
        {
            this.propertiesRetriever = propertiesRetriever;
            this.siteService = siteService;
            this.attachmentUrlRetriever = attachmentUrlRetriever;
        }

        public ActionResult Index()
        {
            // Retrieves the GUID of the first selected attachment from the 'Attachments' property
            Guid guid = propertiesRetriever.Retrieve<CustomWidgetProperties>().Attachments.FirstOrDefault()?.FileGuid ?? Guid.Empty;
            // Retrieves the DocumentAttachment object that corresponds to the selected attachment GUID
            DocumentAttachment attachment = DocumentHelper.GetAttachment(guid, siteService.CurrentSite.SiteID);

            string url = String.Empty;
            if (attachment != null)
            {
                // Retrieves the relative URL of the selected attachment
                url = attachmentUrlRetriever.Retrieve(attachment).RelativePath;
            }

            // Custom logic...

            return View();
        }

// Assigns a selector component to the 'ImageUrl' property
[EditingComponent(UrlSelector.IDENTIFIER)]
// Configures which tabs will be available
[EditingComponentProperty(nameof(UrlSelectorProperties.Tabs), ContentSelectorTabs.Attachment | ContentSelectorTabs.Media)]
// Configures which extensions will be avalable on the media tab
[EditingComponentProperty(nameof(UrlSelectorProperties.MediaAllowedExtensions), ".gif;.png;.jpg;.jpeg")]
// Configures which extensions will be avalable on the attachment tab
[EditingComponentProperty(nameof(UrlSelectorProperties.AttachmentAllowedExtensions), ".gif;.png;.jpg;.jpeg")]
// Configures the media library from which the media files can be selected
[EditingComponentProperty(nameof(UrlSelectorProperties.MediaLibraryName), "Graphics")]
// Returns a string containing the relative URL of the selected image file
public string ImageUrl { get; set; }

// Assigns a selector component to the Newsletters property
[EditingComponent(ObjectSelector.IDENTIFIER)]
// Configures the code name of the selected object type
[EditingComponentProperty(nameof(ObjectSelectorProperties.ObjectType), "newsletter.newsletter")]
// Limits the selected newsletters to exclude email campaigns
[EditingComponentProperty(nameof(ObjectSelectorProperties.WhereConditionProviderType), typeof(NewslettersWhere))]
// Orders items in the selector by their display name alphabetically from Z to A
[EditingComponentProperty(nameof(ObjectSelectorProperties.OrderBy), new string[] { "NewsletterDisplayName DESC" })]
// Returns a list of object selector items
public IEnumerable<ObjectSelectorItem> Newsletters { get; set; } = Enumerable.Empty<ObjectSelectorItem>();

public class NewslettersWhere : IObjectSelectorWhereConditionProvider
{
    // Where condition limiting the objects
    public WhereCondition Get() => new WhereCondition().WhereEquals("NewsletterType", (int)EmailCommunicationTypeEnum.Newsletter);
}

private readonly IComponentPropertiesRetriever componentPropertiesRetriever;
private readonly INewsletterInfoProvider newsletterInfoProvider;

public ObjectSelectorExample(IComponentPropertiesRetriever componentPropertiesRetriever, INewsletterInfoProvider newsletterInfoProvider)
{
    this.componentPropertiesRetriever = componentPropertiesRetriever;
    this.newsletterInfoProvider = newsletterInfoProvider;  
}

public ActionResult Index()
{
    // Retrieves the code name of the selected newsletter from the properties
    string? codeName = componentPropertiesRetriever.Retrieve<CustomWidgetProperties>().Newsletters.FirstOrDefault()?.ObjectCodeName;
    // Retrieves the corresponding newsletter object
    var newsletter = newsletterInfoProvider.Get(codeName, SiteContext.CurrentSiteID);

    // Custom logic...

    return View();
}

[EditingComponent(GeneralSelector.IDENTIFIER)]
[EditingComponentProperty(nameof(GeneralSelectorProperties.DataProviderType), typeof(NewslettersDataProvider))]
public IEnumerable<GeneralSelectorItem> Newsletters { get; set; } = Enumerable.Empty<GeneralSelectorItem>();

private readonly IComponentPropertiesRetriever componentPropertiesRetriever;
private readonly INewsletterInfoProvider newsletterInfoProvider;

public GeneralSelectorExample(IComponentPropertiesRetriever componentPropertiesRetriever, INewsletterInfoProvider newsletterInfoProvider)
{
    this.componentPropertiesRetriever = componentPropertiesRetriever;
    this.newsletterInfoProvider = newsletterInfoProvider;
}

public ActionResult Index()
{
    // Retrieves the code name of the selected email feed from the properties
    string? codeName = componentPropertiesRetriever.Retrieve<CustomWidgetProperties>().Newsletters.FirstOrDefault()?.Identifier;
    // Retrieves the corresponding email feed object
    var newsletter = newsletterInfoProvider.Get(codeName, SiteContext.CurrentSiteID);

    // Custom logic...

    return View();
}