How to Set a Minimum Number of Choices for a Checkbox

Introduction

Would you like to set a minimum number of choices for your Checkbox form field? Currently, you can already set a maximum number of choices by this tutorial. However, did you know using a small PHP code snippet that you can also set a minimum number for these choices as well? In this tutorial, we’ll walk you through the steps on how to set up your Checkbox form field to require a minimum number of selections.

Creating the form

To begin, we’ll need to create a new form and add at least one Checkbox form field to this form.

If you need assistance in creating a form, please review this documentation.

create your form and add your checkbox form field

Adding the snippet to set a minimum number

To set a minimum number of choices, you’ll need to add this code snippet to your site.

If you need any assistance in adding code snippets to your site, please review this tutorial.

/**
 * Set minimum number of choices for a checkbox for the field
 *
 * @link https://wpforms.com/developers/how-to-set-a-minimum-number-of-choices-for-a-checkbox/
 *
 */

function wpf_checkbox_validation( $field_id, $field_submit, $form_data ) {
        
	$field_submit  = (array) $field_submit;

	$count_choices = count( $field_submit );
	if ( $count_choices < 2 ) {
		wpforms()->process->errors[ $form_data['id'] ][ $field_id ] = esc_html__( 'Please select at least 2 options', 'your-text-domain' );
	}

}
add_action( 'wpforms_process_validate_checkbox', 'wpf_checkbox_validation', 10, 3 );

In the code above, any checkbox will require a minimum of two choices.

If a visitor selects any choices that are less than two a message will display under the Checkbox field when the form is submitted.

using this snippet to set a minimum number of choices, the users will see an error and the form will not submit when the minimum options have not been met

Setting a limit for multi page forms

When using multi-page forms, you may not want to wait for the form submission before displaying the error.

For assistance in setting up multi-page forms, please see this documentation.

You can easily show an alert box when the Next button is clicked for multi-page forms.

To use this option, simply add this code snippet to your site instead.

/**
 * Set minimum number of choices for a checkbox form field
 *
 * @link https://wpforms.com/developers/how-to-set-a-minimum-number-of-choices-for-a-checkbox/
 */

function wpf_dev_min_checkbox() {
	?>

	<script type="text/javascript">
		jQuery( '#wpforms-form-1289 button.wpforms-page-next' ).on( 'click', function (e) {
			var minMaxSelection = jQuery( '#wpforms-1491-field_15-container input[type=checkbox]:checked' );
			if ( minMaxSelection.length < 2 ) {
				e.stopPropagation();
				e.preventDefault();
				alert( "minimum of 2 options are required" );
			} 
		});
	</script>
	<?php
}
add_action( 'wpforms_wp_footer_end', 'wpf_dev_min_checkbox' );

This code snippet will target the form ID 1289 and when the Next button is clicked the snippet will first check to see how many choices are selected for the field ID 15 and if it’s less than two, will show an alert message in the browser.

And that’s all you need to set a minimum number of choices on your checkboxes. Would you like to customize the look of these checkboxes? Take a look at our article on How to Customize Checkbox and Radio Fields to Look Like Buttons.

Action references:

FAQ

Q: Can I use this only a specific form and a specific field ID?

A: Absolutely, to use this code on a specific form, use this code snippet:

/**
 * Set minimum number of choices for a checkbox form field
 *
 * @link https://wpforms.com/developers/how-to-set-a-minimum-number-of-choices-for-a-checkbox/
 */

function wpf_dev_checkbox_validation( $field_id, $field_submit, $form_data ) {
	
	// Change the number to match your form ID
	if ( absint( $form_data['id'] ) !== 1289 ) {
        return;
    }
	
		$field_submit  = (array) $field_submit;
		$count_choices = count( $field_submit );
		if ( $count_choices < 2 ) {
			wpforms()->process->errors[ $form_data['id'] ][ $field_id ] = esc_html__( 'Please select at least 2 options', 'your-text-domain' );
		}
}
add_action( 'wpforms_process_validate_checkbox', 'wpf_dev_checkbox_validation', 10, 3 );

If you would like to target a specific form and a specific field ID, use this code snippet.

/**
 * Set minimum number of choices for a checkbox form field
 *
 * @link https://wpforms.com/developers/how-to-set-a-minimum-number-of-choices-for-a-checkbox/
 */

function wpf_dev_checkbox_validation( $field_id, $field_submit, $form_data ) {
	
	// Change the number to match your form ID
	if ( absint( $form_data['id'] ) !== 1289 ) {
        return $field_id;
    }
	
	// Change this number to match the field ID
	if (absint($field_id) === 15 ) {
		$field_submit  = (array) $field_submit;
		$count_choices = count( $field_submit );
		if ( $count_choices < 2 ) {
			wpforms()->process->errors[ $form_data['id'] ][ $field_id ] = esc_html__( 'Please select at least 2 options', 'your-text-domain' );
		}
	}
}
add_action( 'wpforms_process_validate_checkbox', 'wpf_dev_checkbox_validation', 10, 3 );

If you need any help in finding your form and field IDs, please review this tutorial.

Q: Can this work for payment fields as well?

A: Absolutely! To use this for Payment Checkbox Items form field, use this snippet.

/**
 * Set minimum number of choices for a payment checkbox form field
 *
 * @link https://wpforms.com/developers/how-to-set-a-minimum-number-of-choices-for-a-checkbox/
 */
function wpf_dev_limit_payment_field( $field_id, $field_submit, $form_data ) {
    
    $form_id = 731;  // Limit to form id  : Use 0 to target all forms
    $fieldID = 21;  // Limit to field ID : Use 0 to target all checkbox fields
    $min     = 2;  // Change the minimum amount
    $max     = 5;  // Change the maximum amount

    // Limit to specific form if {$form_id} is set
    if ( absint( $form_data[ 'id' ] ) !== $form_id && !empty( $form_id )  ) {
        return;
    }
    // Limit to specific field ID if {$fieldID} is set
    if ( absint( $field_id ) !== $fieldID && !empty( $fieldID ) ) {
        return;
    }
    // Process error if choices count is less than {$min} or greater than {$max}
    if( count( $field_submit ) < $min ) {
	    wpforms()->process->errors[ $form_data[ 'id' ] ] [ $field_id ] = esc_html__( 'Please select a minimum of ' . $min .' choices.', 'your-text-domain' );

		} elseif ( count( $field_submit ) > $max ) {
	    wpforms()->process->errors[ $form_data[ 'id' ] ] [ $field_id ] = esc_html__( 'Please select a maximum of ' . $max . ' choices.', 'your-text-domain' );
    }

}
add_action( 'wpforms_process_validate_payment-checkbox', 'wpf_dev_limit_payment_field', 10, 3 );