Freemaker: assign value in associative array - freemarker

Question

I'm fairly new to Freemarker. I'm trying to create an email template that will list invoices, and then the total amount due at the bottom. However, there needs to be a different "Total Amount" based on the currency (some customers might have 3 invoices in EUR, 2 in GBP, etc).
I'm creating an associative array where the keys are the currency and the values are the total amount in that currency. For each invoice, I need to add the amount due to the value of the correct currency. But I'm getting an error that there is an unexpected character.
Here's the gist:
<#assign totalarr = {} />
<#list invoicelist as invoice>
<#assign invcur = invoice.currency />
<#assign invamt = invoice.amountremaining />
<#assign totalarr[invcur] = totalarr[invcur] + invamt />
</#list>
The error is in the second-to-last line, where I'm trying to add the amount to the total value. Any ideas?
Thanks!
-Kristin

Answer 1

To change hash subvariable value you need to use concatenation like this:
<#assign totalarr = {} />
<#list invoicelist as invoice>
<#assign invcur = invoice.currency />
<#assign invamt = invoice.amountremaining />
<#assign sum = totalarr[invcur]!0 />
<#assign totalarr = totalarr + {invcur : sum + invamt} />
</#list>
<#list totalarr?keys as key>
${key} = ${totalarr[key]}
</#list>