I'm working my way through a family-tree type XML example (rather than copying the book example).

Why is the xsd:date type is so restrictive? The most common date formats used are mm-dd-yyyy and the UK version is dd-mm-yyyy.

I want to create a custom format like dd/mm/yyyy in my schema so that I can validate some dates. I have posted my attempt below.

<xsd:simpleType name="UKDateFormat">
<xsd:restriction base="xsd:string">
<xsd:pattern value="dd/mm/yyyy"/>

Has anyone successfully achieved this before?

Is it possible to assign two data types to an element? e.g. If my dates were to be in "dd/mm/yyyy" or "dd mmm yyyy" formats i'd still like it to pass the schema validation.

<xsd:element name="DATEOFBIRTH" type="xsd:UKDateFormat" minOccurs="0" />

Any tips would be most appreciated.

Many thanks,
Francis

Well to start with you could alter your pattern to:
Unfortunately this would also allow 19/11 1962 and 19 11/1962.
Perhaps a union type with both dd mm yyyy and dd/mm/yyyy styles.
Of course this doen't stop invalid dates such as 29 02 2003 or even more blatantly wrong ones.
There are a number of date regexes shown on the Web but it's actually a very difficult one to code. That's why you may be better sticking to the built in type and just formating between that and your preferred style for display purposes.



--

Joe (Co-author Beginning XML, 3rd edition)

Thanks Joe,

I agree, it's a very complicated business.

My solution will need to be able to format both dates. I think I need to create a complex type with two restrictions, the first goes like this...

<xsd:element name="DATEOFBIRTH" minOccurs="0">
 <xsd:simpleType>
  <xsd:restriction base="xsd:string">
    <xsd:pattern value="[0,1]{1}[0-9]{1}/[0-3]{1}[0-9]{1}/[0-9]{2}"/>
  </xsd:restriction>
 </xsd:simpleType>
</xsd:element>

the second is a bit more tricky...

>Why is the xsd:date type is so restrictive?

I think the answer to this lies in the theory that XML should represent information in a way that's independent of presentation considerations. The XML Schema designers deliberately chose to force you to use a culturally-neutral format.

>The most common date formats used are mm-dd-yyyy

Really? I only know of one country in the world that uses that format.

>and the UK version is dd-mm-yyyy.

dd/mm/yyyy is more common in the UK, but most published documents are likely to write the month as a name.

>I want to create a custom format like dd/mm/yyyy in my schema so that >I can validate some dates. I have posted my attempt below.

It's easy enough to define a pattern such as \d{2}/\d{2}/\d{4}, but there's no way of rejecting 31/02/2004, or even 33/19/2004.

Has anyone successfully achieved this before?

>Is it possible to assign two data types to an element? e.g. If my >dates were to be in "dd/mm/yyyy" or "dd mmm yyyy" formats i'd still >like it to pass the schema validation.

Yes, you can do this with union types. Or (IIRC) you can define more than one pattern.




Michael Kay
http://saxon.sf.net/