Lists

Gogs · December 30th, 2015, 12:29 PM

Hi,

I'm just foraying into XML for the first time and working on some practice scenarios. One of these includes making a representation of a tick list in XML, where a user could select none, one or more, or all options. I was looking at using list as my option. I have seen two different ways of writing it the Wrox "Beginning XML" method:

Code:

<simpleType name=”ContactTagsType”>
 <restriction base=”string”>
 <enumeration value=”author”/>
 <enumeration value=”xml”/>
 <enumeration value=”poetry”/>
 <enumeration value=”consultant”/>
 <enumeration value=”CGI”/>
 <enumeration value=”semantics”/>
 <enumeration value=”animals”/>
 </restriction>
 </simpleType>

with

<simpleType name=”ContactTagsListType”>
 <list itemType=”contacts:ContactTagsType”/>
 </simpleType>

And the W3Schools method which is similar (but I can't seem to get to work):

Code:

<xs:element name="intvalues" type="valuelist"/>
<xs:simpleType name="valuelist">
  <xs:list itemType="xs:integer"/>
</xs:simpleType>
</xs:schema>

The "intvalues" element in a document could look like this (notice that
the list will have five list items):

<intvalues>100 34 56 23 1567</intvalues>

Is there a preference of format? Also I think the latter doesn't work as I have no idea where to put the <intvalues> line :-/

Any pointers advice, would be greatly appreciated,

Gogs

mhkay · December 30th, 2015, 12:54 PM

Both of these are perfectly workable. Representing values as strings rather than integers is going to lead to fewer mistakes, so that would be my preference. One can't really advise on design questions without a lot more background knowledge about the project requirements and constraints.

Gogs · December 30th, 2015, 12:57 PM

Thanks, Michael. I thought that might be the case. If there's anything I have learnt in IT, it's that there is more than one way to skin a cat

With the W3schools example, though, where would the intvalues line fit in? The provided (similar) examples aren't clear on that point.

mhkay · December 30th, 2015, 01:28 PM

The schema you've shown declares an intValues element. So it could be the root element of the document. If you want to use it within another element, you need to add a declaration of the other element to your schema, with intValues in its content model.

Note that's it's not essential to have a schema to describe your XML documents. You may find you can do useful things with XML more quickly if you don't worry about schemas until later.

Gogs · December 30th, 2015, 01:45 PM

Thanks (again) that seems to be making sense :)