Re: Proposal: XML helper functions

Peter Eisentraut wrote:
> On tis, 2010-01-05 at 10:14 -0800, Scott Bailey wrote:
>> One of the problem with shredding XML is that it is very kludgy to get a
>> scalar value back from xpath. The xpath function always returns an array
>> of XML. So for example, to extract a numeric value you need to:
>> 1) use xpath to get the node
>> 2) get the first element of the XML array
>> 3) cast that to varchar
>> 4) cast that to numeric
>
> There has been talk about adding something like xpath_string,
> xpath_number, xpath_boolean for fetching xpath expressions that don't
> return nodesets. I think that would fit your use case.

The first two sound very much like what I'm looking for. I'm unsure
about the third. Is it's purpose to extract the scalar value of an
expression and cast to bool as the other two do, or is it to identify if
the xpath expression returned any nodes like xmlexists?

Scott