Question

It is easy to calculate a sum, an average or a maximum accross set of fields using built-in xpath functions.

But is it possible to calculate a product?

Assuming I have repeating elements like

<my:table>
    <my:row>
        <my:value>10</my:value>
    </my:row>
    <my:row>
        <my:value>20</my:value>
    </my:row>
    <my:row>
        <my:value>30</my:value>
    <my:row>
</my:table>

(the number of my:rows may vary).

i need to have a formula multiplying all my:values: 10*20*30 (and working with any number of rows).

Any ideas?

Please do not suggest code solutions, I need this for a restricted form.

Answer 1

Using conditional hack described here, I finally assembled the solution.

Inside my:row, create a running product field my:valueCumul, populated using a formula to refer to previous row, and leveraging the conditional hack to override NaN for the first row:

../my:value * 
concat(
(count(../preceding-sibling::my:row[1]) = 0) * 1,
substring(../preceding-sibling::my:row[1]/my:valueCumul, 1, (count(../preceding-sibling::my:row[1]) = 1) * string-length(../preceding-sibling::my:row[1]/my:valueCumul))
)

Outside the table you can easily refer to my:valueCumul in the last row to get total product:

../my:row[count(../my:row)]/my:valueCumul

The nice features of this solution are:

• Works in a browser form in any sharepoint environment
• Is not impacted by “16 calculations” threshold
• The formula is robust to row removal and shifts