Re: XML Schema quiz on default values

So what should an instance document look like to have the default value
"Hello World"? Does this mean that the default value is of no practical use
for an xsd:string type?

-d


On 24 August 2012 10:05, Costello, Roger L. <[email protected]> wrote:

> Thank you Michael and Pete for correcting my misunderstanding.
>
> Allow me to correct the answer to my quiz:
>
> I wrote this as the answer to my quiz:
>
>     >  Answer: the value of Title is the empty string, not the default
> value.
>     >  The reason is that the empty string is a valid value of the string
> data type.
>
> However, the correct answer is:
>
>  Answer: the value of Title is the default value ("Hello World"). The XML
> Schema specification explains why:
>
>     An element with a non-empty default value whose
>     simple type definition includes the empty string in
>     its lexical space will nonetheless never receive that
>     empty string value, because the default value will
>     override it.
>
> /Roger
>
>
> -----Original Message-----
> From: Costello, Roger L.
> Sent: Thursday, August 23, 2012 5:47 PM
> To: [email protected]
> Subject: XML Schema quiz on default values
>
> Hello Folks,
>
> Recall that when you declare an element (or attribute) you can give it a
> default value.
>
> For example, I give the Altitude element a default value of 100:
>
>         <xs:element name="Altitude" type="xs:integer" default="100" />
>
> In an instance document, if you wish for Altitude to have the default
> value, then you can simply create it as an empty element:
>
>         <Altitude></Altitude>
>
> The value of Altitude is 100.
>
> Let's take another example. Here I declare the Title element to be of type
> string and give it a default value, "Hello World":
>
>         <xs:element name="Title" type="xs:string" default="Hello World" />
>
> Now in my instance document I create an empty Title element:
>
>         <Title></Title>
>
> Quiz: What is the value of Title?
>
> Scroll down to see the answer ...
>
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> Answer: the value of Title is the empty string, not the default value. The
> reason is that the empty string is a valid value of the string data type.
> If you want Title to have the default value then you must explicitly enter
> the default value:
>
>         <Title>Hello World</Title>
>
> /Roger
>
>


-- 
____________________________________________________________
   Daniel Dui - [email protected] - skype: danieldui