How to use FreeForm Pro or EE Extension Hooks

Question

I am a .NET/Java developer so I'm not very familiar with PHP although I have dabbled with it in the past and am a total noob with Expression Engine. I am working on a project at work along side our front-end site developer who is using EE to build a membership site. We are using FreeForm Pro to create 2 or 3 user forms.

The first is a simple form asking for first name, last name and email address. When the user supplies this information and clicks the submit button we want to be able to verify the person's existence in a table that was not created by the installation of the FreeForm module. At the moment I copied the basic form code example from FreeForm documentation pages and pasted it to a Template in EE:

<h3>Contact Us</h3>
<p>
    To send us a message, please fill out the form below.
    We’ll get back to you shortly!
</p>

{exp:freeform:form
    form_name="contact"
    return="contact_us/thank_you"
}
    <dl>
    {freeform:all_form_fields}
        <dt><label>{freeform:field_label}</label></dt>
        <dd>{freeform:field_output}</dd>
    {/freeform:all_form_fields}
    </dl>
    {if freeform:captcha}
        <p>Please enter the word you see in the image below:</p>
        <p>{freeform:captcha}<br />
        <input type="text" name="captcha" style="width:140px;" /></p>
    {/if}
    <p>{freeform:submit}</p>
    {if freeform:no_results}
        <p>
            Specified form was not found. Please make sure you have
            specified the correct short name of the form in the
            <b>form_name</b> parameter.
        </p>
    {/if}
{/exp:freeform:form}

When submit button on this form is clicked the data gets saved into the table exp_freeform_form_entries_1. This is unnecessary for us but not a big deal. What we want to do is verify with a table that was not created by the FreeForm module like a membership_staging table to determine if the person is already registered. The membership_staging table is a table that was imported from another application.

We were thinking we could use one of the extension hooks like freeform_module_insert_begin to redirect the forms functionality to do a simple query and comparison to the membership_staging table but are have not been able to figure out how the hooks are triggered and how to use them correctly. I copy/pasted the following hook code from the FreeForm documentation into my EE Template.

if (ee()->extensions->active_hook('freeform_module_insert_begin') === TRUE)
{
    $field_input_data = ee()->extensions->universal_call(
        'freeform_module_insert_begin',
        $field_input_data,
        $entry_id,
        $form_id,
        $this
    );

    if (ee()->extensions->end_script === TRUE)
    {
        return;
    }
}

I am not sure if this piece of code is being executed when the submit button is clicked and have no idea how to test if it is. I have scoured the internet for the past week looking for tutorials or examples of how to utilize hooks in an EE template but only find tutorials and example on how to build extensions and none of them talk about hooks and how to use them.

I would greatly appreciate it if someone could assist me in filling in the blank.

Answer 1

You need to write what's called an extension.

https://ellislab.com/expressionengine/user-guide/development/extensions.html

Basically, an extension fires when a given hook goes by, you can do your check in the aux table there, and then return to the form submission.

The Freeform docs show what hooks are available to work with.

Answer 2

Here we go...

So you have your first form (taking first name, last name, and email address). It's a FreeForm form, displayed on the client side, with rendered template code you've shown. When a user fills in the data and submits, it sends a POST request to what is called and Action ID (ACTid), which is a sort of API portal between the client and the ExpressionEngine (custom)? module. Here's an example ACT address:

https://www.domains-rock.com/?ACT=666

When a module is properly installed, there is a DB table (generally called exp_action) that gets inserted rows that create an association between an ACTion ID and a module's class method. For FreeForm, it would have a table row that associated ACTion ID 666 with the method that handles the form submission. That method then has a code hook in it. The engine looks at that hook and looks at the exp_extensions table to see if any installed extensions want to run their own class's methods inside of the code in the FreeForm submission method.

> i submit form
> FeeForm EE addon receives it
> starts processing it, but starts off with the insert_begin hook
>  - your extension hooks to that, so it takes over code control here
>  -  -  you get passed form info, whatever, into your extension method
>  -  -  you modify it and return it, or return false if invalid, whatever
>  - your extension ends, return form submission control to FreeForm
> FreeForm finishes up with the submission process.