Handlebar syntax to calculate the sum of JSON elements

Integrator.io
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1

Hello,
Could anyone help with the handlebar syntax to use to get the sum of the `amount` elements in the JSON below?.....

"applied_discounts": [
{
"id": "total-coupon",
"amount": "0.0000",
},
{
"id": "26",
"amount": "22.9400",
},
{
"id": "28",
"amount": "10.000",
}
],
So the expected result would be 32.9400 (0 + 22.9400 + 10.000)
Also, for a bonus point, could this result be assigned to a variable? So the result can then be checked to see if it is greater than zero?

Thank you in advance
2

Hi, @davidgospel.

I got the intended result with this syntax:

{{add applied_discounts.0.amount applied_discounts.1.amount applied_discounts.2.amount}}

Of course, that’s assuming you already know the number of array items.

Handlebars statements aren’t designed for variable assignment. To keep a new sum available in your flow, you would have to assign the value resolved above to a new or existing field or JavaScript variable.

3

Hi Stephen,
Thanks for the quick response.

Unfortunately we don't know the size of the `applied_discounts` array.

So do you know what syntax could be used when the size of the array is unknown?

4

Good question. I tried all the obvious handlebars solutions: looping, nesting, the sum function...and Help Center and Google searches.

Unfortunately, there doesn't seem to be a built-in answer for this particular question. I'd love to hear how others have attacked the problem.

Here's where you might go from here:

  • Can you transform the data structure so that all amounts are children within one array? Then you can call sum.
  • Loop through the array in JavaScript to store the total.
  • It seems that as long as you know the upper bound of the expected number of applied_discounts, you can use the helper add on additional items, without throwing an error. That is, even though your sample data contained only three elements, it didn't break anything to try to include additional indices. For example, I still got the right total with this statement:

{{add applied_discounts.0.amount applied_discounts.1.amount applied_discounts.2.amount applied_discounts.3.amount applied_discounts.4.amount}}

5

Hi Stephen,
Thanks for looking into this.

Funnily enough, I came to the same solution: just include many elements in the Add helper.
I assume this helper includes a check to see if a value exists before performing the add function.

Also, I was able to include the Add helper within my existing handlebars - which calculates the Item Rate to send to NetSuite.
This Rate value includes any discounts applied to an order in Big Commerce

Here is my full handlebars....

{{#if products[*].applied_discounts.0.amount}} {{subtract products[*].price_ex_tax (divide (add products[*].applied_discounts.0.amount products[*].applied_discounts.1.amount products[*].applied_discounts.2.amount products[*].applied_discounts.3.amount) products[*].quantity)}} {{else}} {{products[*].price_ex_tax}} {{/if}}
6

@davidgospel: That's a master class in handlebars. Thanks, and I hope others can benefit from it as well.

>I assume this helper includes a check...

From my limited tests, it seems that an undefined array element behaves like an empty variable and it's added +0, with no harm. Don't try this hack in JavaScript. ;)