Extending Form Builder

After working through this guide, you will have learned:

  • How to include custom CSS into the form builder
  • How to write a custom finisher editor
  • How can the form builder be adjusted

An in-depth reference on how to extend the form builder using custom JavaScript can be found in the start page of the Form Builder API documentation.

Adjusting the Form Builder with Custom CSS

Let’s say you want to adjust the form builder with a custom CSS file inside Your.Package/Resources/Public/FormBuilderAdjustments.css. Then, you need to tell the form builder to load this additional stylesheet as well. You can do that using an entry inside Settings.yaml of your package which looks as follows:

        files: ['resource://Your.Package/Public/FormBuilderAdjustments.css']
        sorting: 200

Most important is the sorting property, as it defines the order in which the CSS files are included. Every sorting up to 100 is reserved for internal use by the form builder, so you should use sorting numbers above 100 unless you have a good reason to do otherwise.


Loading additional JavaScript files into the form builder works in the same manner.

Overriding Form Builder Handlebars Template

Let’s say we want to adjust the header of the form builder, such that it displays your company up there as well. For that, we need to modify the default handlebars template for the header area.


If you modify handlebars templates, you might need to adjust them after a new version of the form builder has been released! Modification of handlebars templates is useful for unplanned extensibility, but you should only do it as last resort!

The default template is located inside TYPO3.FormBuilder/Resources/Private/FormBuilderTemplates/Header.html and looks as follows:

<h1>Form Builder - {{TYPO3.FormBuilder.Model.Form.formDefinition.label}}</h1>
{{#if TYPO3.FormBuilder.Model.Form.currentlyLoadingPreview}}
   <span id="typo3-formbuilder-loading">Loading..</span>

<ul id="typo3-formbuilder-toolbar">
   <li class="typo3-formbuilder-preset">
      {{view TYPO3.FormBuilder.View.Header.PresetSelector}}
   <li class="typo3-formbuilder-preview">
      {{#view TYPO3.FormBuilder.View.Header.PreviewButton class="typo3-formbuilder-button icon"}}Preview{{/view}}
   <li class="typo3-formbuilder-save">
        {{#view TYPO3.FormBuilder.View.Header.SaveButton class="typo3-formbuilder-button icon"}}Save{{/view}}

We can just copy it to Your.Package/Resources/Private/FormBuilderTemplates/Header.html and adjust it as needed, modifying the part inside the <h1>...</h1> to:

<h1>Your Company Form Builder - {{TYPO3.FormBuilder.Model.Form.formDefinition.label}}</h1>

Then, we need to tell the form builder that we want to use a different handlebars template for the header. For that, we need the following Settings.yaml:

      Header: resource://Your.Package/Private/FormBuilderTemplates/Header.html


Make sure that your package is loaded after the FormBuilder package if you want to override such settings.

Creating a Custom Editor

Every form element is edited on the right side of the Form Builder in the element options panel. In order to be flexible and extensible, the element options panel is a container for editors which, as a whole, edit the form element. There are a multitude of predefined editors, ranging from a simple text input field up to a grid widget for editing properties.

All editors for a given form element are defined inside the formElementTypes definition, looking as follows:

# we are now inside TYPO3:Form:presets:[presetName]:formElementTypes
      placeholder: # an arbitrary key for identifying the editor instance
        sorting: 200 # the sorting determines the ordering of the different editors inside the element options panel
        viewName: 'JavaScript.View.Class.Name' # the JavaScript view class name which should be used here
        # additionally, you can define view-specific options here
    # here, you can define some more editors.

We will now create a custom editor for rendering a select box, and will add it to the File Upload form element such that a user can choose the file types he allows. The finished editor is part of the standard FormBuilder distribution inside TYPO3.FormBuilder/Resources/Private/CoffeeScript/elementOptionsPanelEditors/basic.coffee.


If you want to create your completely own editor, you need to include the additional JavaScript file. How this is done is explained in detail inside Adjusting the Form Builder with Custom CSS

The Basic Setup


We’ll develop the editor in CoffeeScript, but you are of course free to also use JavaScript.

We will extend our editor from TYPO3.FormBuilder.View.ElementOptionsPanel.Editor.AbstractPropertyEditor:

TYPO3.FormBuilder.View.ElementOptionsPanel.Editor.SelectEditor = AbstractPropertyEditor.extend {
   templateName: 'ElementOptionsPanel-SelectEditor'

Then, we will create a basic handlebars template and register it underneath ElementOptionsPanel-SelectEditor (as described in Overriding Form Builder Handlebars Template). We’ll just copy over an existing editor template and slightly adjust it:

<div class="typo3-formbuilder-controlGroup">
   <div class="typo3-formbuilder-controls">
      [select should come here]


Don’t forget to register the handlebars template ElementOptionsPanel-SelectEditor inside your Settings.yaml.

Now that we have all the pieces ready, let’s actually use the editor inside the TYPO3.Form:FileUpload form element:

# we are now inside TYPO3:Form:presets:[presetName]:formElementTypes
         sorting: 200
         viewName: 'TYPO3.FormBuilder.View.ElementOptionsPanel.Editor.SelectEditor'

After reloading the form builder, you will see that the file upload field has a field: [select should come here] displayed inside the element options panel.

Now that we have the basics set up, let’s fill the editor with life by actually implementing it.

Implementing the Editor

Everything inside here is just JavaScript development with EmberJS, using bindings and computed properties. If that sound like chinese to you, head over to the EmberJS website and read it up.

We somehow need to configure the available options inside the editor, and come up with the following YAML on how we want to configure the file types:

  sorting: 200
  label: 'Allowed File Types'
  propertyPath: 'properties.allowedExtensions'
  viewName: 'TYPO3.FormBuilder.View.ElementOptionsPanel.Editor.SelectEditor'
      value: ['doc', 'docx', 'odt', 'pdf']
      label: 'Documents (doc, docx, odt, pdf)'
      value: ['xls']
      label: 'Spreadsheet documents (xls)'

Furthermore, the above example sets the label and propertyPath options of the element editor. The label is shown in front of the element, and the propertyPath points to the form element option which shall be modified using this editor.

All properties of such an editor definition are made available inside the editor object itself, i.e. the SelectEditor now magically has an availableElements property which we can use inside the Handlebars template to bind the select box options to. Thus, we remove the [select should come here] and replace it with Ember.Select:

{{view Ember.Select contentBinding="availableElements" optionLabelPath="content.label"}}

Now, if we reload, we already see the list of choices being available as a dropdown.

Saving the Selection

Now, we only need to save the selection inside the model again. For that, we bind the current selection to a property in our view using the selectionBinding of the Ember.Select view:

{{view Ember.Select contentBinding="availableElements" optionLabelPath="content.label" selectionBinding="selectedValue"}}

Then, let’s create a computed property selectedValue inside the editor implementation, which updates the value property and triggers the change notification callback @valueChanged():

SelectEditor = AbstractPropertyEditor.extend {
   templateName: 'ElementOptionsPanel-SelectEditor'
   # API: list of available elements to be shown in the select box; each element should have a "label" and a "value".
   availableElements: null

   selectedValue: ((k, v) ->
      if arguments.length >= 2
         # we need to set the value
         @set('value', v.value)

      # get the current value
      for element in @get('availableElements')
         return element if element.value == @get('value')

      # fallback if value not found
      return null
   ).property('availableElements', 'value').cacheable()

That’s it :)

Creating a Finisher Editor

Let’s say we have implemented an DatabaseFinisher which has some configuration options like the table name, and you want to make these configuration options editable inside the Form Builder. This can be done using a custom handlebars template, and some configuration. In many cases, you do not need to write any JavaScript for that.

You need to do three things:

  1. Register the finisher as a Finisher Preset
  2. Configure the finisher editor for the form to include the newly created finisher as available finisher
  3. create and include the handlebars template
      yourPresetName: # fill in your preset name here, or "default"
        # 1. Register your finisher as finisher preset
             implementationClassName: 'Your\Package\Finishers\DatabaseFinisher'
                    # Configure the finisher editor for the form to include
                    # the newly created finisher as available finisher
                      label: 'Database Persistence Finisher'
                      templateName: 'Finisher-YourPackage-DatabaseFinisher'
      # include the handlebars template
      Finisher-YourPackage-DatabaseFinisher: resource://Your.Package/Private/FormBuilderTemplates/DatabaseFinisher.html

Now, you only need to include the appropriate Handlebars template, which could look as follows:

   {{#view Ember.Button target="parentView" action="remove"

<div class="typo3-formbuilder-controlGroup">
   <label>Database Table</label>
   <div class="typo3-formbuilder-controls">
      {{view Ember.TextField valueBinding="currentCollectionElement.options.databaseTable"}}


Creating a custom validator editor works in the same way, just that they have to be registered underneath validatorPresets and the editor is called validators instead of finishers.