Validation is extremely important for form fields to ensure that forms do the job, the submitted data is correct, and that it will be processed as intended.
In this article, I will discuss the practical use cases for advanced form field validation rules in JetFormBuilder and how to implement them.
Also, I will talk about the custom add-on that can interact with the existing website’s queries and compare them with the data submitted to the current field. The cool thing there is that you can get creative with the queries, so your creativity is the limit for its use cases.
Without further ado, let’s get started with the tools for field validation and cases for using them.
If you are a JetFormBuilder user, you might have already checked the section about advanced validation in the plugin’s Documentation. Here, I will go a bit more into detail and provide examples of how to use them.
First, it’s important to say that we are talking about field validation happening on the field, not the entire form level. This means that when you add a new field and go to the right panel (the Block tab), you will see the settings for validation. It can have three values:
In this article, we will only talk about the Advanced type and its rules.
After choosing the Advanced tab, you will see the “Add rule” button appear. After clicking it, you will see a pop-up with a set of rule types:
There are six of them, and more might be added. As of now, there are:
You can add several rules to one field.
Let’s go through each of the rule types and the usage examples.
The logic here is straightforward – the value in the input must be equal to the value you set. Now, the fun part: when Pandora’s box of dynamic options opens.
So, you can set the value manually, e.g., “123,” and if the user enters something else, the error will be shown. It’s easy.
However, you can fetch any of the fields that belong to the current post or user and, of course, the other fields from the same forms that can be used either alone or in combination. Except for the Posts and Users, there are two interesting options available: query variables and Option Pages.
All these options can be used with other validation rule types, not just “Equals.”
⛏️ Use cases for the “Equals” rule
These rule types can be used to make customers use certain characters or avoid some of them. Also, it can work for words or values of other fields or custom fields dynamically fetched from current or queried posts and users (see the last example from the previous section).
⛏️ Use cases for the “Must contain characters” / “Must not contain characters” rules
Regular expressions give more flexibility in setting up a range of allowed/restricted symbols than just a normal symbol field.
⛏️ Use cases for the “Matches regular expression” / “Doesn’t match regular expression” rules
Don’t forget to explain the requirements to the users.
This type of validation rule gives developers a lot of freedom. You will find a template for a callback right in the dialog window for the validation rules.
⛏️ Use cases for the Server-side validation callbacks
function custom_jfb_field_validation( $value, $context ): bool {
// Check if the email is already registered
$user = get_user_by( 'email', $value );
if ( $user ) {
return false; // Email is already registered
}
return true; // Email is not registered
}function custom_jfb_field_validation( $value, $context ): bool {
$prohibited_words = array( 'table', 'spoon', 'forest' );
foreach ( $prohibited_words as $word ) {
if ( stripos( $value, $word ) !== false ) {
return false; // The value contains a prohibited word
}
}
return true; // The value is acceptable
}Forms are a very powerful and flexible asset if you use the right instrument that has all the functionality to implement your ideas. They can be the main part of users’ dashboards, pass a lot of information using hidden fields, guide customers by means of multi-step forms with conditional logic, help with selecting complex values and purchasing goods, and so many more cases.
In this article, I’ve used different examples to demonstrate how you can not only build such forms but also validate the submitted information in a few different ways.
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