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Subtotal Merge Tag (for Calculations)

A simple way of getting the subtotal for your Gravity Form calculations.

Last updated | Written by 331 Comments

  • December 10, 2018: Added a proper plugin header.

  • December 1, 2018: Updated to support Gravity Forms 2.4.

  • November 19, 2014: Updated to support decimal quantities. Props daniaux!

  • April 1, 2014: Fixed issue where single product fields with no quantity input were not calculated.

  • March 17, 2014: Fixed issue where option fields of the radio input type were not included in the generated merge tag string.

  • November 20, 2013: Fixed issue where "Subtotal" merge tag was not displaying in Formula merge tag drop down until it had been added manually. Thanks to @realph for helping track this bug down.

  • October 9, 2013: Fixed issue where checkbox option fields with ten or more inputs were not being calculated correctly.

  • September 12, 2013: Fixed issue with Single Product fields when the "Disable Quantity" option was enabled.

  • September 11, 2013: Fixed issue where checkbox option fields were not correctly calculated.

Show All Updates

Stop! There's a better way.

This snippet is available as a plugin with Gravity Perks, a suite of over 30 premium Gravity Forms plugins!

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<?php
/**
* --- STOP! ---
* Get the latest version:
* https://gravitywiz.com/documentation/gravity-forms-ecommerce-fields/
* -------------
*
* Calculation Subtotal Merge Tag
*
* Adds a {subtotal} merge tag which calculates the subtotal of the form.
*
* This merge tag can only be used within the "Formula" setting of Calculation-enabled fields (i.e. Number, Calculated Product).
*
* @version 1.2
* @author David Smith <david@gravitywiz.com>
* @license GPL-2.0+
* @link https://gravitywiz.com/subtotal-merge-tag-for-calculations/
* @copyright 2018 Gravity Wiz
*
* Plugin Name: Gravity Forms Subtotal Merge Tag
* Plugin URI: https://gravitywiz.com/subtotal-merge-tag-for-calculations/
* Description: Adds a {subtotal} merge tag which calculates the subtotal of the form.
* Author: Gravity Wiz
* Version: 1.2
* Author URI: https://gravitywiz.com
*/
class GWCalcSubtotal {
public static $merge_tag = '{subtotal}';
function __construct() {
// front-end
add_filter( 'gform_pre_render', array( $this, 'maybe_replace_subtotal_merge_tag' ) );
add_filter( 'gform_pre_validation', array( $this, 'maybe_replace_subtotal_merge_tag_submission' ) );
// back-end
add_filter( 'gform_admin_pre_render', array( $this, 'add_merge_tags' ) );
}
/**
* Look for {subtotal} merge tag in form fields 'calculationFormula' property. If found, replace with the
* aggregated subtotal merge tag string.
*
* @param mixed $form
*/
function maybe_replace_subtotal_merge_tag( $form, $filter_tags = false ) {
foreach( $form['fields'] as &$field ) {
if( current_filter() == 'gform_pre_render' && rgar( $field, 'origCalculationFormula' ) )
$field['calculationFormula'] = $field['origCalculationFormula'];
if( ! self::has_subtotal_merge_tag( $field ) )
continue;
$subtotal_merge_tags = self::get_subtotal_merge_tag_string( $form, $field, $filter_tags );
$field['origCalculationFormula'] = $field['calculationFormula'];
$field['calculationFormula'] = str_replace( self::$merge_tag, $subtotal_merge_tags, $field['calculationFormula'] );
}
return $form;
}
function maybe_replace_subtotal_merge_tag_submission( $form ) {
return $this->maybe_replace_subtotal_merge_tag( $form, true );
}
/**
* Get all the pricing fields on the form, get their corresponding merge tags and aggregate them into a formula that
* will yeild the form's subtotal.
*
* @param mixed $form
*/
static function get_subtotal_merge_tag_string( $form, $current_field, $filter_tags = false ) {
$pricing_fields = self::get_pricing_fields( $form );
$product_tag_groups = array();
foreach( $pricing_fields['products'] as $product ) {
$product_field = rgar( $product, 'product' );
$option_fields = rgar( $product, 'options' );
$quantity_field = rgar( $product, 'quantity' );
// do not include current field in subtotal
if( $product_field['id'] == $current_field['id'] )
continue;
$product_tags = GFCommon::get_field_merge_tags( $product_field );
$quantity_tag = 1;
// if a single product type, only get the "price" merge tag
if( in_array( GFFormsModel::get_input_type( $product_field ), array( 'singleproduct', 'calculation', 'hiddenproduct' ) ) ) {
// single products provide quantity merge tag
if( empty( $quantity_field ) && ! rgar( $product_field, 'disableQuantity' ) )
$quantity_tag = $product_tags[2]['tag'];
$product_tags = array( $product_tags[1] );
}
// if quantity field is provided for product, get merge tag
if( ! empty( $quantity_field ) ) {
$quantity_tag = GFCommon::get_field_merge_tags( $quantity_field );
$quantity_tag = $quantity_tag[0]['tag'];
}
if( $filter_tags && ! self::has_valid_quantity( $quantity_tag ) )
continue;
$product_tags = wp_list_pluck( $product_tags, 'tag' );
$option_tags = array();
foreach( $option_fields as $option_field ) {
if( is_array( $option_field['inputs'] ) ) {
$choice_number = 1;
foreach( $option_field['inputs'] as &$input ) {
//hack to skip numbers ending in 0. so that 5.1 doesn't conflict with 5.10
if( $choice_number % 10 == 0 )
$choice_number++;
$input['id'] = $option_field['id'] . '.' . $choice_number++;
}
}
$new_options_tags = GFCommon::get_field_merge_tags( $option_field );
if( ! is_array( $new_options_tags ) )
continue;
if( GFFormsModel::get_input_type( $option_field ) == 'checkbox' )
array_shift( $new_options_tags );
$option_tags = array_merge( $option_tags, $new_options_tags );
}
$option_tags = wp_list_pluck( $option_tags, 'tag' );
$product_tag_groups[] = '( ( ' . implode( ' + ', array_merge( $product_tags, $option_tags ) ) . ' ) * ' . $quantity_tag . ' )';
}
$shipping_tag = 0;
/* Shipping should not be included in subtotal, correct?
if( rgar( $pricing_fields, 'shipping' ) ) {
$shipping_tag = GFCommon::get_field_merge_tags( rgars( $pricing_fields, 'shipping/0' ) );
$shipping_tag = $shipping_tag[0]['tag'];
}*/
$pricing_tag_string = '( ( ' . implode( ' + ', $product_tag_groups ) . ' ) + ' . $shipping_tag . ' )';
return $pricing_tag_string;
}
/**
* Get all pricing fields from a given form object grouped by product and shipping with options nested under their
* respective products.
*
* @param mixed $form
*/
static function get_pricing_fields( $form ) {
$product_fields = array();
foreach( $form["fields"] as $field ) {
if( $field["type"] != 'product' )
continue;
$option_fields = GFCommon::get_product_fields_by_type($form, array("option"), $field['id'] );
// can only have 1 quantity field
$quantity_field = GFCommon::get_product_fields_by_type( $form, array("quantity"), $field['id'] );
$quantity_field = rgar( $quantity_field, 0 );
$product_fields[] = array(
'product' => $field,
'options' => $option_fields,
'quantity' => $quantity_field
);
}
$shipping_field = GFCommon::get_fields_by_type($form, array("shipping"));
return array( "products" => $product_fields, "shipping" => $shipping_field );
}
static function has_valid_quantity( $quantity_tag ) {
if( is_numeric( $quantity_tag ) ) {
$qty_value = $quantity_tag;
} else {
// extract qty input ID from the merge tag
preg_match_all( '/{[^{]*?:(\d+(\.\d+)?)(:(.*?))?}/mi', $quantity_tag, $matches, PREG_SET_ORDER );
$qty_input_id = rgars( $matches, '0/1' );
$qty_value = rgpost( 'input_' . str_replace( '.', '_', $qty_input_id ) );
}
return floatval( $qty_value ) > 0;
}
function add_merge_tags( $form ) {
$label = __('Subtotal', 'gravityforms');
?>
<script type="text/javascript">
// for the future (not yet supported for calc field)
gform.addFilter("gform_merge_tags", "gwcs_add_merge_tags");
function gwcs_add_merge_tags( mergeTags, elementId, hideAllFields, excludeFieldTypes, isPrepop, option ) {
mergeTags["pricing"].tags.push({ tag: '<?php echo self::$merge_tag; ?>', label: '<?php echo $label; ?>' });
return mergeTags;
}
// hacky, but only temporary
jQuery(document).ready(function($){
var calcMergeTagSelect = $('#field_calculation_formula_variable_select');
calcMergeTagSelect.find('optgroup').eq(0).append( '<option value="<?php echo self::$merge_tag; ?>"><?php echo $label; ?></option>' );
});
</script>
<?php
//return the form object from the php hook
return $form;
}
static function has_subtotal_merge_tag( $field ) {
// check if form is passed
if( isset( $field['fields'] ) && is_array( $field['fields'] ) ) {
$form = $field;
foreach( $form['fields'] as $field ) {
if( self::has_subtotal_merge_tag( $field ) )
return true;
}
} else {
if( isset( $field['calculationFormula'] ) && strpos( $field['calculationFormula'], self::$merge_tag ) !== false )
return true;
}
return false;
}
}
new GWCalcSubtotal();
view raw gw-calc-subtotal.php hosted with ❤ by GitHub

Currently, there is no easy way to get the current total (let’s call it the subtotal) of the form for use in calculations. It’s possible but you’ll have to enter all of your product merge tags into a long and complicated formula to get the subtotal.

This snippet helps you avoid that hassle by providing a {subtotal} merge tag for use in your Gravity Form calculations.

Please note: The {subtotal} merge tag is only available in fields that support calculations.

How do I install this snippet?

Easy peasy. Just copy and paste the code above into your theme's functions.php file.

How do I use this functionality?

This snippet will add a new “Subtotal” merge tag to the merge tag select available for the “Formula” setting on Calculation fields. Selecting this option will insert the {subtotal} merge tag into your “Formula” setting. You can then use all available mathematical operations available to this field to manipulate this subtotal as needed.

formula-subtotal-merge-tagFormula Setting: Subtotal Merge Tag
formula-subtotal-taxFormula Setting: Subtotal Used to Calculate Tax

Did this resource help you do something awesome with Gravity Forms? Then you'll absolutely love Gravity Perks; a suite of 29+ essential add-ons for Gravity Forms with support you can count on.

Comments

  1. I’m using Stripe as my payment processor for Gravity Forms. I need to add tax to my form, but my current setup just sends the total amount to Stripe, and I would have to figure out how much was tax separately. How does tax show up in Stripe through the ecommerce perk? Will it show up in Stripe’s tax field, or will it just show up as the total transaction amount?

    Reply

    • Support for mapping the Tax field to Stripe’s tax field is on our roadmap but not currently supported. For now, the Tax field is included in the cumulative total sent to Stripe.

  2. Does this subtotal save with the form? I am having issues with running some gv_math because I am trying to access the Totals from a form but it tells me that Totals are allowed in gv_math. I am wondering if this saves as a number or something that I can access later? My Total field is literally summing up 100s of items so to make a calculated # field is not possible given the form. Any thoughts?

    Reply

    • The {subtotal} merge tag does not impact how the field data is saved. What you see on submission should be what is saved in that field. I haven’t used gv_match but I would not expect this functionality to impact whether or not that functionality works.

    • But are you saying that subtotal is saved with the form? Or is it just doing its thing on the live form and then doesn’t go anywhere once submitted? Gravity View Math doesn’t let us do math on the Total form field in Gravity Views so I am trying to come up with a way to get my Total over without it being incompatible. I was hoping this might be it. Does it save as a number in the database?

    • The value of the field is saved with the entry including whatever the calculated value of the {subtotal} merge tag. Including the {subtotal} merge tag in a calculation-enabled field does not impact how the calculation-enabled field works. If you Gravity View typically works with calculation-enabled fields, it should work with the calculation-enabled field that contains the {subtotal} merge tag.

  3. Please help. I have a dev environment and am getting this error msg:

    Warning: Invalid argument supplied for foreach() in /srv/bindings/38c825ddfc6b4c72b486890a3c77ee96/code/wp-content/plugins/gravity-forms-add-subtotal-merge-tag-master/gf_subtotal.php on line 234

    This is not showing up in the Production environment.

    Reply

  5. I’m using this snippet for a donation form for my client.

    When any decimal appears after the dollar amount $10.(50cents), the Credit Card fields throws an error:

    This value must match the regex pattern. (/\A[a-zA-Z0-9_\-]+\z/ does not match for the value monthlyrecurring_40_1month_10.5).

    Any helpful ideas would be appreciated.

    Thank you!

    Reply

    • My apologies. I needed to upgrade Stripe Add-On from 2.5 to 2.5.4. That fixed my issue. Thank you for responding.

  6. I need some help installing this snippet with a skilled developer, can anyone help us update our gravity form with tax calculation subtotal issue as mentioned above? I can pay you of course for the help. Currently our form is not collecting tax and it’s a problem.

    Reply

  7. Sorry to bug you again. I updated to WordPress 5.0 and gravity forms 2.4.3. somehow now when i am using the subtotal merge tag, all the calculations are drastically off in the negative. I have 3 products, all with a price of 0, then an option field with checkboxes for each product, containing multiple selections with prices. On my tax calculation field (.0875*{subtotal}), if I select say a product that is $75 and a product that is $85, I get a calculation of -$85,414.00. if I change the calculation formula to only be {subtotal} and nothing else, the $75 and $85 product tally to Price: -$745,915.00. Could something have changed in the way this merge tag is tallying the subtotal? Thanks David!

    Reply

    • I am experiencing the same issue. I had to roll back to WordPress 5.0 and Gravity Forms 2.4.2. I experience the issue with WordPress 5.0.1 and Gravity Forms 2.4.2 and the problem seems to worsen with 2.4.3.

  8. The newest version work with Gravity Forms 2.4.1 but breaks after updating to WordPress 5 with the following notice:

    The plugin gravity-forms-add-subtotal-merge-tag-master/gf_subtotal.php has been deactivated due to an error: The plugin does not have a valid header.

    Any thoughts on how to resolve this?

    Reply

  10. Hi David, Im hoping you can help me out with this.

    i’ve began seeing a warning on all pages where i have a form, when this snippet is in my functions file: Warning: Invalid argument supplied for foreach() in /home/redacted/functions.php on line 597

    597 appears to be at the end of the snippet, located in the // check if form is passed section:

    foreach( $form[‘fields’] as $field ) {

    I updated gravity forms to 2.4 at some point this past week. I haven’t made any other changes to the functions file or gravity forms. The snippet was working fine for the past few months.

    Thanks Chris

    Reply

    • It appears that this doesn’t work anymore with the latest version of Gravity Forms, 2.4.1. If there is a fix, I would love to know. Thanks, Lynne

    • Hi, I’m having the same issue that Christopher Grasso reports. With Gravity 3.4.1 installed the Subtotals routine generates multiple error messages Warning: Invalid argument supplied for foreach() in /home/{redacted …}/functions.php referencing the line foreach( $form[‘fields’] as $field ) {

      I’ve restored the site to Gravity 3.3.6 and the form works correctly again. Thank you for assisting!

  11. Hi David, I want to be sure that a “SubTotal” field is “accessible” by the Stripe Addon in the Feed settings

    I want to create a subscription Subtotal and a Setup Fee subtotal and use the STripe Addon to create a feed that uses those subtotals Currently. The way I see it the Stripe Feed only accepts Product Fields or the Total. I want to be sure that the subtotal fields also work with the Stripe Feed.

    Reply

    • This snippet does not provide a Subtotal field, Frank. Are you referring to the GP eCommerce Fields plugin? If so, no, the Subtotal field is not available to Stripe. This is something we’d like to add support for in the future.

    • Hello,

      The sub-total is actually not quite fully working correctly. When I select the “products”I want to calculate in the sub-total, it calculates everything, not just what I selected. Note, the way I have the products structured is some of them had the same name although different product fields with different GF product numbers. I thought that might be causing it so I adjusted the names of the ones I want to include in the sub-total and still having the same issue. Could it be the names in the database are still the same or is this a bug?

      Thanks.

  13. Thanks for this. I used this solution to allow me to use the subtotal in a conditional statement for another field. Very helpful.

    Reply

  14. In general, I have a form http://35.226.46.43/create-shipment/, I need to pass it a little bit. make the connection between the areas allow delivery from MANHATTAN to MANHATTAN – $ 75 etc. And change the price calculation depending on the weight if more than 20 lb then + 0.75 $ per lb How can i do it? Thx

    Reply

  15. I’m interested in passing the WooCommerce cart total into a Gravity Form via merge tag so that I can apply additional calculations based on user selections. Specifically, I’m trying to create a lease calculator that converts the cart total into a monthly lease price based on user selecting a lease type and lease terms. Based on the user selections, a lease rate would be multiplied by the cart total in order to calculate the monthly lease. Can this be done using Gravity Wiz?

    Reply

  16. Having a hard time showing taxes ony form, used the subtotal as mentioned above but it totals to a crazy large number. Unsure what I’m doing wrong. Help!

    Reply

  17. I’m using this code to calculate a discount. It works perfectly (subtotal * number of checkboxes checked * discount percentage)

    The issue is that this “discount” is being added to the total, not subtracted from it. From what I can tell, there’s no way to subtract the total from the actual total, is there?

    Reply

    • How can I do that? The discount is a calculation, so I can’t add it as a negative amount.

      Or I can’t figure out how, anyway.

    • That doesn’t seem to work.

      My calculation [(({subtotal}.05){Number:29})-({subtotal}*.05)] works perfectly to calculate the discount. (FYI, it’s 5% discount per add-on they check, which I’m pulling from the Number:29 field, which is a sum total of checkboxes checked, minus one discount for the initial add-on)

      If I add a – in front of the formula, the math somehow becomes wrong.

      No minus sign and the discount adds up to $256.25 (which is right; 25% of the total of all 6 add-ons – 5% per add-on after the 1st one)

      If I add a minus sign, it adds up to -$358.75, which is wrong.

      Same exact formula, but adding the – in front of it somehow breaks the equation.

    • Aha!

      I added another set of parenthesis around the whole thing and now it’s calculating properly!

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