How to Use REGEX in Registration Forms

Table of Contents

What is REGEX? How to set up REGEX rules in a registration form Use cases #1: Restrict the input for the Email field to a specific domain #2: Accept only business emails for the Email field Other examples Best practices #1: Test your patterns #2: Implementation tips #3: Provide clear error messages

REGEX patterns allow you to control the data that registrants enter on your registration forms. In this article, you will discover how to use REGEX rules for data validation of the input fields of your registration forms.

What is REGEX?

REGEX, or Regular Expression, is a dynamic and flexible syntax that allows you to define specific patterns for strings. By applying REGEX rules to standard and custom fields in Goldcast registration forms, you can enhance data integrity by restricting the types of values registrants are permitted to enter.

For instance, you can utilize REGEX to ensure that the email field exclusively accepts business emails, not personal ones.

How to set up REGEX rules in a registration form

For Events

Log into Goldcast Studio, and open your preferred event using the Events tab on the left sidebar.
Once you're on the event dashboard, use the left sidebar to navigate to the Registration → Page & Form tab.
Scroll to the Registration Form section, and click the Edit button.
To add a regex pattern to a form field, hover over it, and select its edit icon.
Click the Validation tab and enter the regex pattern in the Regular Expression Pattern field.
Click Update.
Click Save.

For Webinars

Log into Goldcast Studio, and open your preferred webinar using the Events tab on the left sidebar.
Once you're on the webinar dashboard, click Registration on the tabs at the top of the page.
Next, navigate to the Form sub-tab and click the Edit Form button.
To add a regex pattern to a form field, hover over it, and select its edit icon.
Click the Validation tab and enter the regex pattern in the Regular Expression Pattern field.
Click Update.
Click Save.

Use cases

#1: Restrict the input for the Email field to a specific domain

This option is useful for organizers planning company events that are open only to employees. For example, the regular expression pattern below is structured so that the Email field can only accept email addresses ending in goldcast.io:

[^\n\r]+@[Gg]oldcast.io

Users who enter an email address that doesn't match the criteria outlined in the regular expression pattern will receive an error message. If the address matches the criteria, it will be accepted.

#2: Accept only business emails for the Email field

You can also use regex to ban specific email domains from registering for your events. For example, if you want to prevent attendees from registering with their personal emails, you can use the Regex patterns:

^(?!(?:.*@(?:gmail\.com|yahoo\.com|hotmail\.com|outlook\.com)$)).*$

Alternate pattern to ban all non-business emails

Option #1:

Option #2:

In the example below, when a registrant enters a Gmail, Yahoo, Hotmail, or Outlook domain in the Email field, the verbose error message in the Custom Error Message input will show and prevent the user from completing the registration process.

Note: The regex example above is case-sensitive and only bans the domains if they are entered in lowercase. The regex can be modified to make it not case-sensitive, but a simpler solution is going to the Data tab and selecting the Lowercase Text Case option for the email field. This will force emails to be entered in lowercase.

Other examples

Field	Regex Pattern	Description	Examples of Valid Entries
Name	^[a-zA-Z\s'-]{2,50}$	This pattern allows: Letters Spaces Hyphens Apostrophes Length between 2-50 characters	John Smith Mary-Jane O'Connor Jean-François
Phone Number	^\+?\d{1,4}[-.\s]?\(?\d{1,3}\)?[-.\s]?\d{1,4}[-.\s]?\d{1,4}$	This pattern supports: Optional + prefix for country code Optional parentheses around area code Separators (space, dash, or period) Various international formats	+1 (555) 123-4567 555.123.4567 +44 20 7123 4567
US Zip Code	^\d{5}(-\d{4})?$	Supports: 5-digit ZIP code Optional 4-digit extension	12345 12345-6789

Field

Regex Pattern

Description

Examples of Valid Entries

Name

^[a-zA-Z\s'-]{2,50}$

This pattern allows:

Letters
Spaces
Hyphens
Apostrophes
Length between 2-50 characters

John Smith
Mary-Jane O'Connor
Jean-François

Phone Number

^\+?\d{1,4}[-.\s]?$?\d{1,3}$?[-.\s]?\d{1,4}[-.\s]?\d{1,4}$

This pattern supports:

Optional + prefix for country code
Optional parentheses around area code
Separators (space, dash, or period)
Various international formats

+1 (555) 123-4567
555.123.4567
+44 20 7123 4567

US Zip Code

^\d{5}(-\d{4})?$

Supports:

5-digit ZIP code
Optional 4-digit extension

12345
12345-6789

Best practices

#1: Test your patterns

When adding regex patterns, test with both valid and invalid inputs. Consider edge cases specific to your registrants and cover them in the pattern. Use sites like https://regexr.com/ and https://regex101.com/ to test if your regex patterns are correct and work as intended.

#2: Implementation tips

Use case-insensitive flags when appropriate.
Add anchors (^ and $) to match entire string
To change length requirements:
- {8,} → Change the minimum length
- {3,16} → Modify range
To add/remove character classes:
- \d for digits
- [A-Z] for uppercase
- [a-z] for lowercase
- [^a-zA-Z0-9] for special characters

#3: Provide clear error messages

Customize the error labels for invalid responses. Make it clear and specific so the user knows which inputs are permitted.

The error messages for invalid responses incorporate the field label by default.

Text entered into the Error Label field overrides and replaces the field-label text.

Custom Error Labels allow you to create custom error messages for form fields. Unlike the Error Label field, any text entered into this field will override the default error message entirely.

Building a Goldcast Registration Page

Registration Setup

Creating and Editing Registration Forms

How to Use REGEX in Registration Forms

Adding track selection to your registration form

Adding Your Goldcast Form to an External Registration Page

How To Embed a Marketo Form on Your Registration Page

How To Embed a HubSpot Form on Your Registration Page

UTM Tracking in Goldcast

Add & Manage Tracking Pixels & Tags

How To Add a Location Block to the Registration Page

How to Use REGEX in Registration Forms

What is REGEX?

How to set up REGEX rules in a registration form

For Events

For Webinars

Use cases

#1: Restrict the input for the Email field to a specific domain

#2: Accept only business emails for the Email field

Alternate pattern to ban all non-business emails

Other examples