# Dynamic max value. / Checkbox

**URL:** <https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627>\
**Category:** Get Help\
**Tags:** gravity-wiz\
**Created:** [April 28, 2020, 5:08pm UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627 "2020-04-28T17:08:06Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![Adey](https://sea2.discourse-cdn.com/flex020/user_avatar/community.gravityforms.com/adey/32/4126_2.png) [@Adey](https://community.gravityforms.com/u/Adey)\
**Post date:** [April 28, 2020, 5:08pm UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627/1 "2020-04-28T17:08:06Z")

</div>

This is not my strong point as you may have guessed. The checkboxes function below works well. It would however be brilliant if you could dynamically change the **max** value below based on a field on the form (a number field).

This way you could pass a value from another form and limit the choices based on that value. I have tried messing around but have not clue as to how to refer to the specific number field in the form. I min could also be dynamic even better.

I do appreciate this forum it has some very helpful and talented people.

```auto
new GFLimitCheckboxes(25, 
		array(
    5 => array(
        'min' => 1, 
        'max' => **4**
        )
    ));

```

```auto
/**
* Limit How Many Checkboxes Can Be Checked
* http://gravitywiz.com/2012/06/11/limiting-how-many-checkboxes-can-be-checked/
*/

class GFLimitCheckboxes {

    private $form_id;
    private $field_limits;
    private $output_script;

    function __construct($form_id, $field_limits) {

        $this->form_id = $form_id;
        $this->field_limits = $this->set_field_limits($field_limits);

        add_filter("gform_pre_render_$form_id", array(&$this, 'pre_render'));
        add_filter("gform_validation_$form_id", array(&$this, 'validate'));

    }

    function pre_render($form) {

        $script = '';
        $output_script = false;

        foreach($form['fields'] as $field) {

            $field_id = $field['id'];
            $field_limits = $this->get_field_limits($field['id']);

            if( !$field_limits // if field limits not provided for this field
                || RGFormsModel::get_input_type($field) != 'checkbox' // or if this field is not a checkbox
                || !isset($field_limits['max']) // or if 'max' is not set for this field
                )
                continue;

            $output_script = true;
            $max = $field_limits['max'];
            $selectors = array();

            foreach($field_limits['field'] as $checkbox_field) {
                $selectors[] = "#field_{$form['id']}_{$checkbox_field} .gfield_checkbox input:checkbox";
            }

            $script .= "jQuery(\"" . implode(', ', $selectors) . "\").checkboxLimit({$max});";

        }

        GFFormDisplay::add_init_script($form['id'], 'limit_checkboxes', GFFormDisplay::ON_PAGE_RENDER, $script);

        if($output_script):
            ?>

            <script type="text/javascript">
            jQuery(document).ready(function($) {
                $.fn.checkboxLimit = function(n) {

                    var checkboxes = this;

                    this.toggleDisable = function() {

                        // if we have reached or exceeded the limit, disable all other checkboxes
                        if(this.filter(':checked').length >= n) {
                            var unchecked = this.not(':checked');
                            unchecked.prop('disabled', true);
                        }
                        // if we are below the limit, make sure all checkboxes are available
                        else {
                            this.prop('disabled', false);
                        }

                    }

                    // when form is rendered, toggle disable
                    checkboxes.bind('gform_post_render', checkboxes.toggleDisable());

                    // when checkbox is clicked, toggle disable
                    checkboxes.click(function(event) {

                        checkboxes.toggleDisable();

                        // if we are equal to or below the limit, the field should be checked
                        return checkboxes.filter(':checked').length <= n;
                    });

                }
            });
            </script>

            <?php
        endif;

        return $form;
    }

    function validate($validation_result) {

        $form = $validation_result['form'];
        $checkbox_counts = array();
		

        // loop through and get counts on all checkbox fields (just to keep things simple)
        foreach($form['fields'] as $field) {

            if( RGFormsModel::get_input_type($field) != 'checkbox' )
                continue;

            $field_id = $field['id'];
            $count = 0;

            foreach($_POST as $key => $value) {
                if(strpos($key, "input_{$field['id']}_") !== false)
                    $count++;
            }

            $checkbox_counts[$field_id] = $count;

        }

        // loop through again and actually validate
        foreach($form['fields'] as &$field) {

            if(!$this->should_field_be_validated($form, $field))
                continue;

            $field_id = $field['id'];
            $field_limits = $this->get_field_limits($field_id);

            $min = isset($field_limits['min']) ? $field_limits['min'] : false;
            $max = isset($field_limits['max']) ? $field_limits['max'] : false;

            $count = 0;
            foreach($field_limits['field'] as $checkbox_field) {
                $count += rgar($checkbox_counts, $checkbox_field);
            }

            if($count < $min) {
                $field['failed_validation'] = true;
                $field['validation_message'] = sprintf( _n('You must select at least %s item.', 'You must select at least %s items.', $min), $min );
                $validation_result['is_valid'] = false;
            }
            else if($count > $max) {
                $field['failed_validation'] = true;
                $field['validation_message'] = sprintf( _n('You may only select %s item.', 'You may only select %s items.', $max), $max );
                $validation_result['is_valid'] = false;
            }

        }

        $validation_result['form'] = $form;

        return $validation_result;
    }

    function should_field_be_validated($form, $field) {

        if( $field['pageNumber'] != GFFormDisplay::get_source_page( $form['id'] ) )
    		return false;

        // if no limits provided for this field
        if( !$this->get_field_limits($field['id']) )
            return false;

        // or if this field is not a checkbox
        if( RGFormsModel::get_input_type($field) != 'checkbox' )
            return false;

        // or if this field is hidden
        if( RGFormsModel::is_field_hidden($form, $field, array()) )
            return false;

        return true;
    }

    function get_field_limits($field_id) {

        foreach($this->field_limits as $key => $options) {
            if(in_array($field_id, $options['field']))
                return $options;
        }

        return false;
    }

    function set_field_limits($field_limits) {

        foreach($field_limits as $key => &$options) {

            if(isset($options['field'])) {
                $ids = is_array($options['field']) ? $options['field'] : array($options[$fieldgrab]);
            } else {
                $ids = array($key);
            }

            $options['field'] = $ids;

        }

        return $field_limits;
    }

}

```

---

<div class="post-metadata">

**Author:** ![chrishajer](https://sea2.discourse-cdn.com/flex020/user_avatar/community.gravityforms.com/chrishajer/32/88_2.png) [@chrishajer](https://community.gravityforms.com/u/chrishajer)\
**Post date:** [April 28, 2020, 7:01pm UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627/2 "2020-04-28T19:01:34Z")

</div>

Hi Adey. I will leave this open and ping the developer @spivurno but I suspect the best support for that customization would come from Gravity Wiz directly or if you are a Gravity Perks customer, from their talented support staff. As I said though, I’ll leave this open to see if anyone can suggest an approach for you.

---

<div class="post-metadata">

**Author:** ![Adey](https://sea2.discourse-cdn.com/flex020/user_avatar/community.gravityforms.com/adey/32/4126_2.png) [@Adey](https://community.gravityforms.com/u/Adey)\
**Post date:** [April 28, 2020, 7:21pm UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627/3 "2020-04-28T19:21:31Z")

</div>

Thanks Chris (again).

I’m not a percs customer, I found that example online and it appeared to be open to all. If @spivurno could shed some light it would be wonderful. I fully appreciate him and his team are very busy although I have noticed he steps in to assist from time to time on the forums.

Thanks for leaving this open. 👍

---

<div class="post-metadata">

**Author:** ![david](https://sea2.discourse-cdn.com/flex020/user_avatar/community.gravityforms.com/david/32/2517_2.png) [@david](https://community.gravityforms.com/u/david)\
**Post date:** [April 29, 2020, 1:23am UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627/4 "2020-04-29T01:23:45Z")

</div>

Hi Adey,

This basic snippet does not support it; however, if you decide to pick up a copy of Gravity Perks and use [Gravity Forms Limit Checkboxes](https://gravitywiz.com/documentation/gravity-forms-limit-checkboxes/), we have a snippet that works with it to allow dynamically setting the limit.

> <https://gist.github.com/spivurno/42ca347547088029b986e2b5287ccaea>

---

<div class="post-metadata">

**Author:** ![Adey](https://sea2.discourse-cdn.com/flex020/user_avatar/community.gravityforms.com/adey/32/4126_2.png) [@Adey](https://community.gravityforms.com/u/Adey)\
**Post date:** [April 29, 2020, 9:37am UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627/5 "2020-04-29T09:37:59Z")

</div>

Thanks David,

I tried the function with the parameters below.

Am I correct in thinking it works like so

I set the form ID in this case 25.

The number field on form to refence is id 6

The checkbox ID is 5.

The number field #6 with either be 4 or 8 depending on what gets passed to it from another form.

I tried below and it has no affect on the checkbox number limitations. If I have misunderstood the functionality then please do let me know thanks.

```auto
new GPLC_Conditional_Limits( array(

    'form_id' => 25,

    'field_id' => 5,

    'conditionals' => array(

        array(

            'min' => 4,

            'max' => 4,

            'conditionalLogic' => array(

                'logicType' => 'all',

                'actionType' => 'show',

	            'rules' => array(

                    array(

                        'fieldId' => 6,

                        'operator' => 'is',

                        'value' => '4'

                    )

	            )

            )

        ),

	    array(

		    'min' => 8,

		    'max' => 8,

		    'conditionalLogic' => array(

			    'logicType' => 'all',

                'actionType' => 'show',

			    'rules' => array(

				    array(

					    'fieldId' => 6,

					    'operator' => 'is',

					    'value' => '8'

				    )

			    )

		    )

	    )

    )

) );

```

---

<div class="post-metadata">

**Author:** ![Adey](https://sea2.discourse-cdn.com/flex020/user_avatar/community.gravityforms.com/adey/32/4126_2.png) [@Adey](https://community.gravityforms.com/u/Adey)\
**Post date:** [April 29, 2020, 12:17pm UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627/6 "2020-04-29T12:17:22Z")

</div>

Ok scrap that sorry it was if I purchased the gravity perk. I’m stuck then. Not to worry thanks for replying anyway,

---

<div class="post-metadata">

**Author:** ![richardw8k](https://sea2.discourse-cdn.com/flex020/user_avatar/community.gravityforms.com/richardw8k/32/2354_2.png) [@richardw8k](https://community.gravityforms.com/u/richardw8k)\
**Post date:** [January 5, 2022, 8:48am UTC](https://community.gravityforms.com/t/dynamic-max-value-checkbox/4627/7 "2022-01-05T08:48:25Z")

</div>