Sample Google Tag Manager Episerver Forms element block.

TagManagerElementBlock.cs

using AlloyWithFind.Business.SelectionFactories;
using EPiServer.DataAbstraction;
using EPiServer.DataAnnotations;
using EPiServer.Forms.Core;
using EPiServer.Forms.Core.Internal;
using EPiServer.Forms.EditView;
using EPiServer.Shell.ObjectEditing;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace AlloyWithFind.Models.FormElements
{
    /// <summary>
    /// Google Tag Manager category and form name element block.
    /// </summary>
    [ContentType(DisplayName = "TagManagerElementBlock", GUID = "2fdc67f3-cdb1-4fab-9f00-bf22cf5565ae", GroupName = ConstantsFormsUI.FormElementGroup, Description = "Contains Tag Manager category and form name for a form submission event.", Order = 100)]
    public class TagManagerElementBlock : ElementBlockBase, IViewModeInvisibleElement, IElementRequireClientResources // NOTE! IElementRequireClientResources is in Episerver internal namespace!
    {
        // hide label field from editors
        [ScaffoldColumn(false)]
        public override string Label { get => base.Label; set => base.Label = value; }

        // hide description (aka tooltip) field from editors
        [ScaffoldColumn(false)]
        public override string Description { get => base.Description; set => base.Description = value; }

        [CultureSpecific(true)]
        [Display(Name = "FormName", Description = "Enter the Google Tag Manager form name here.", GroupName = SystemTabNames.Content, Order = 10)]
        public virtual string FormName { get; set; }

        [SelectOne(SelectionFactoryType = typeof(GtmCategorySelectionFactory))]
        [CultureSpecific(false)]
        [Display(Name = "CategoryName", Description = "Google Tag Manager category name.", GroupName = SystemTabNames.Content, Order = 20)]
        public virtual string CategoryName { get; set; }

        // this is shown to editors
        public override string EditViewFriendlyTitle => $"GTM submission, Form name: '{FormName}', Category name: '{CategoryName}'";

        public IEnumerable<Tuple<string, string>> GetExtraResources()
        {
            return new List<Tuple<string, string>>
            {
                // injected to the page, contains the GTM javascript to push to datalayer
                new Tuple<string, string>("script", "/Static/js/gtm-submission.js?v=1.0")
            };
        }

        public override bool IsElementValidToSubmit()
        {
            // documentation says that this means can the data be stored as submitted data
            // no this doesn't need to be saved
            return false;
        }
    }
}