Using the Helper classes

Helper classes enable you to generate standard HTML elements for the back office as well as for module configuration pages.

PrestaShop 1.5 introduced 5 Helper classes, along with the Helper parent class: HelperForm, HelperOptions, HelperList, HelperView, and HelperHelpAccess. Among these, only the first three will be useful to developer, the last two being more internal helpers for the first three.

PrestaShop 1.6 adds a handful more: HelperCalendar, HelperUploader, HelperImageUploader, HelperKpi, HelperKpiRow, HelperTreeCategories, and HelperTreeShops. Again of these have no direct use developers: their features are directly handled by the main Helpers. For instance, the new uploading system, handled by HelperUpload (and HelperImageUploader for product images), is directly used by HelperForm when generating a <input type="file"> element.

Therefore, you will most of the time only deal with HelperForm.

The Main Helpers

All the helper classes inherit from the Helper parent class:

• HelperForm: used to generate an edition form for an object of type ObjectModel. Example: editing the client's profile.

• HelperOptions: used to generate a configuration form, the values of which are stored in the configuration table. Example: the "Preferences" page.

• HelperList: used to generate a table of elements. The elements can belong to ObjectModel-type objects, but they do not have to. Example: client list, order status list, etc.

The Helper Templates

The helpers use Smarty templates which are found in the following folder: admin/themes/default/template/helpers/name_of_the_helper/

Each template can be overloaded.

Helper Overloading

An AdminController can overload any Helper template, simply by creating a .tpl file of the same name in the folder named admin/themes/default/controllers/name_of_the_controller/helpers/name_of_the_helper/

If possible, it should extend the parent template, not just replace it. Smarty 3 allows for inheritance by declaring {block name=""} tags. A child template can overload a parent block by opening a block of the same name.

In addition to this section, you can read how to use helpers to overload a back office template.

Template inheritance example: adding a new type of field in a form

For the sake of this example, let's change the edition for the client's addresses. We want a field that would display the name and e-mail of the client, if these are known, or an e-mail input field otherwise.

We must create a new template: /admin-dev/themes/default/template/controllers/addresses/helpers/form/form.tpl

This template will contain the following code:

{extends file="helpers/form/form.tpl"}
 
{block name="field"}
    {if $input.type == 'text_customer'}
        {if isset($customer)}
            ...
        {else}
            ...
        {/if}
    {else}
        {$smarty.block.parent}
    {/if}
{/block}

We first declare the template's parent, then we can overload its field block. That block contains the field display. Our code checks the field type:

• If it is of type text_customer, then it handles the content display.

• If it is of any other type, it gives way to the parent's handling code.