Adding a field type to Umbraco Forms

    This builds on the "adding a type to the provider model" chapter


    Add a new class to the Visual Studio solution, make it inherit from Umbraco.Forms.Core.FieldType and fill in the constructor:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using Microsoft.AspNetCore.Http;
    using Umbraco.Forms.Core.Enums;
    using Umbraco.Forms.Core.Models;
    using Umbraco.Forms.Core.Services;
    namespace MyFormsExtensions
        public class MyCustomField : Umbraco.Forms.Core.FieldType
            public MyCustomField()
                this.Id = new Guid("08b8057f-06c9-4ca5-8a42-fd1fc2a46eff"); // Replace this!
                this.Name = "My Custom Field";
                this.Description = "Render a custom text field.";
                this.Icon = "icon-autofill";
                this.DataType = FieldDataType.String;
                this.SortOrder = 10;
                this.SupportsRegex = true;
                this.FieldTypeViewName = "FieldType.MyCustomField.cshtml";
            // You can do custom validation in here which will occur when the form is submitted.
            // Any strings returned will cause the submit to be invalid!
            // Where as returning an empty ienumerable of strings will say that it's okay.
            public override IEnumerable<string> ValidateField(Form form, Field field, IEnumerable<object> postedValues, HttpContext context, IPlaceholderParsingService placeholderParsingService)
                var returnStrings = new List<string>();
                if (!postedValues.Any(value => value.ToString().ToLower().Contains("custom")))
                    returnStrings.Add("You need to include 'custom' in the field!");
                // Also validate it against the original default method.
                returnStrings.AddRange(base.ValidateField(form, field, postedValues, context, placeholderParsingService));
                return returnStrings;

    In the constructor, we specify the standard provider information (remember to set the ID to a unique ID).

    And then we set the field type specific information. In this case a preview Icon for the form builder UI and what kind of data it will return, this can either be string, longstring, integer, datetime or boolean.

    You will then need to register this new field as a dependency.

    using Umbraco.Cms.Core.Composing;
    using Umbraco.Cms.Core.DependencyInjection;
    using Umbraco.Forms.Core.Providers;
    namespace MyFormsExtensions
        public class Startup : IComposer
            public void Compose(IUmbracoBuilder builder)

    Partial view

    Then we will start building the view for the default theme of the form at Views\Partials\Forms\Themes\default\FieldTypes\FieldType.MyCustomField.cshtml.

    The file name for the partial view should match the value set on the FieldTypeViewName property.

    @model Umbraco.Forms.Mvc.Models.FieldViewModel
    <input type="text" name="@Model.Name" id="@Model.Id" class="text" value="@Model.ValueAsHtmlString" maxlength="500"
            @{if (string.IsNullOrEmpty(Model.PlaceholderText) == false) { <text> placeholder="@Model.PlaceholderText" </text> }}
            @{if (Model.Mandatory || Model.Validate) { <text> data-val="true" </text> }}
            @{if (Model.Mandatory) { <text> data-val-required="@Model.RequiredErrorMessage" </text> }}
            @{if (Model.Validate) { <text> data-val-regex="@Model.InvalidErrorMessage" data-val-regex-pattern="@Html.Raw(Model.Regex)" </text> }} />

    This will be rendered when the default theme is used.

    Umbraco backoffice view

    The final step involves building the HTML view which will be rendered in Umbraco as an example of how our end result will look:

        type="text" tabindex="-1"
        style="max-width: 100px"

    In the HTML you can access settings via field.settings, e.g. {{field.settings.Caption}} to render a "Caption" setting. It is also possible to access prevalues via field.parsedPreValues.

    For built-in field types, Umbraco Forms look for this file in the folder: App_Plugins\UmbracoForms\backoffice\Common\FieldTypes\ and will expect to find a file with a name matching the class's name, i.e. mycustomfield.html.

    As this location is cleared following a dotnet clean command, it's better to host the files for custom field types in a different location, such as App_Plugins\UmbracoFormsCustomFields\backoffice\Common\FieldTypes\mycustomfield.html.

    With a file in that location, you can apply the following override to the custom field type's C# representation:

    public override string GetDesignView() =>

    Field settings

    Field settings that will be managed in the backoffice by editors creating forms using the custom field type can be added to the C# class as properties with a Setting attribute:

        [Setting("My Setting", Description = "Help text for the setting", View = "TextField", DisplayOrder=10)]
        public string MySetting { get; set; }

    The View attribute defines the client-side view used when rendering a preview of the field in the form's designer. Umbraco Forms ships with a number of these, found in App_Plugins\UmbracoForms\backoffice\Common\SettingTypes\.

    Again though, as this location is cleared following a dotnet clean command, if you require a custom setting type view, it's better to host them in different location, such as App_Plugins\UmbracoFormsCustomFields\backoffice\Common\SettingTypes\mycustomsettingfield.html.

    To reference the file the setting should be configured with a full path to the view, e.g.:

        [Setting("My Setting",
            Description = "Help text for the setting",
            View = "~/App_Plugins/UmbracoFormsCustomFields/backoffice/Common/SettingTypes/mycustomsettingfield.html",
        public string MySetting { get; set; }

    Backoffice entry rendering

    The third and final client-side view file used for settings is in the rendering of the submitted values for the field in the "Entries" section of the backoffice.

    These are defined by the RenderView property of a field type and are found in App_Plugins\UmbracoForms\backoffice\Common\RenderTypes\.

    As for the other files, if you require a custom render type view, it's better to host them in different location, such as App_Plugins\UmbracoFormsCustomFields\backoffice\Common\RenderTypes\mycustomrenderfield.html.

    To reference the file you should override the RenderView property, e.g.:

    public override string RenderView => "~/App_Plugins/UmbracoFormsCustomFields/backoffice/Common/RenderTypes/mycustomrenderfield.html";