How to filter on multiple attributes in XMLStarlet?

Question

For example, given:

<fruit>
   <banana source='Ecuador' category='I'>
      <quantity>1</quantity>
   </banana>
   <banana source='Costa Rica' category='I'>
      <quantity>1</quantity>
   </banana>
</fruit>

Say I want to change

<banana source='Costa Rica' category='I'> 

to

<banana source='Costa Rica' category='II'> 

or its quantity to 2, how would I reference it if I want to filter on both the source and the initial category value?

---

I'm trying to do the following:

xmlstarlet ed -u "/fruit/banana[@source='Ecuador' @category='I']/quantity" -v 2

...but this results in a syntax error, as follows:

Invalid predicate: /fruit/banana[@source='Ecuador' @category='I']/quantity
Invalid expression: /fruit/banana[@source='Ecuador' @category='I']/quantity

Answer 1

After quite a bit of trial and error, reached a solution:

I need to close and re-open [] with the next attribute. For example:

xmlstarlet ed -u "/fruit/banana[@source='Ecuador'][@category='I']/quantity" -v 2 example.xml

And would correctly output:

<?xml version="1.0"?>
<fruit>
  <banana source="Ecuador" category="I">
    <quantity>2</quantity>
  </banana>
  <banana source="Costa Rica" category="I">
    <quantity>1</quantity>
  </banana>
</fruit>

Edit: also works:

xmlstarlet ed -u "/fruit/banana[@source='Ecuador' and @category='I']/quantity" -v 2 example.xml