XML Validation on attributes

[sroberts82]

Hi,
Im currently looking at using XML Schemas to validate my code. Here is my problem. I want to validate by attribute so that if attribute is x i have 1 child element otherwise i have 2:

<element att="x">
<cap>a</cap>
<cap>b</cap>
</element>

<element att="y">
<cap>a</cap>
<cap>b</cap>
</element>

The only way i can see to it is to define 2 different elements x and y but that doesnt make sense it the context I am using as X and Y ARE attributes of my element and it makes the XML more complex which is not good for the user who has to write it. So my question is can I validate based on attribute? Thanks in advance,

 

[tsuji]

[1] That is the kind of constraint not readily making itself available to scope of validation of the w3c xml schema language. It is of the kind of constraint commonly called co-occurence.

[2] If you run the xml document against a simple self-made template xsl document, but to the point of the bigger idea, in tandem with the validation by WXSL, you can get satisfaction quite easily. The template can be constructed very simply like this.
[tt]
<?xml version="1.0" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="

http://www.w3.org/1999/XSL/Transform">

<xslutput method="text" />
<xsl:template match="element"> <!-- the context -->
<xsl:choose>
<xsl:when test="not ((@att = 'x' and count(child::*) = 1) or (@att = 'y' and count(child::*) = 2))">
<xsl:text>Assertion fails:&#x0a;"If the &lt;element&gt;'s attribute @att is x, it should only contain one child node, or &#x0a;if the &lt;element&gt;'s attribute @att is y, it should only contain two child nodes."&#x0a;</xsl:text>
</xsl:when>
<xsltherwise>
<xsl:text>Assertion succeeds.&#x0a;</xsl:text>
</xsltherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>
[/tt]
From the output of the transformation, you get the validation result.

[3] From the simple demo in [2], and if you want more sophisticated industry-wide device, you can take a look at Schematron. The construction of a validation basically is not very different from the [2] but loaded with systematic and enough sophiscation on the messaging.