Schematron: Test that a string matches an ID from a list of available IDs

[jcb]

I have an XML file that contains a list of possible question answers as well as the correct answer. I want to use schematron to verify that the correct answer value (a string) exists in the list of possible answer IDs.

I'm comparing the string value to the list IDs, but am coming up short.

XML:

Code: Select all

<question>
    <div class="answer" id="i149">
        <div class="choice" id="i152">
            <div class="list" id="i154">
                <ol>
                    <li id="i155">Red</li>
                    <li id="i156">Blue</li>
                    <li id="i157">Green</li>
                    <li id="i158">Yellow</li>
                </ol>
            </div>
        </div>
    </div>
    <div class="response-processing" id="i159">
        <div class="condition" id="i161">
            <div class="correct" id="i162">
                <div class="response" id="i163">
                    <p>
                        <a class="answer-ref" href="#i152" id="i164">i1555</a>
                    </p>
                    <p>
                        <a class="answer-ref" href="#i152" id="i165">i156</a>
                    </p>
                    <p>
                        <a class="answer-ref" href="#i152" id="i166">i157</a>
                    </p>
                </div>
            </div>
        </div>
    </div>
</question>

Schematron rule:

Code: Select all

<pattern id="answerIDnotLocal">
        <let name="answer" value="ancestor::question/div[@class='answer']/div[@class='choice']/div[@class='list']/ol//li/@id"/>
        <rule context="a[@class='answer-ref']">
            <assert test=". = $answer">This <value-of select="."/> doesn't match an available answer id.</assert>
        </rule>
    </pattern>

However, all 3 <a class="answer-ref">s trigger the error when only the first one should (with value i1555 - actual value should be i155).

[Radu]

Hi,

How about if you move the <let> expression one line down inside the <rule> element so that it's executed in the right context?

Regards,
Radu

[jcb]

Regardless of the <let>, the answer ended up being the use of quantified expressions:

Code: Select all

<pattern id="answerIDnotLocal">
        <rule context="question">
            <let name="answer" value="div[@class='response-processing']/div[@class = 'condition']/div[@class = 'correct']"/>
            <let name="choice" value="div[@class = 'answer']//div[@class = 'list']//li/@id"/>
            <assert test="every $a in $answer satisfies $a = $choice">This question doesn't match an available answer id.</assert>
        </rule>
</pattern>