Re: [Saxon-JS 2] Creating a JSON object

If you're doing this repeatedly, then you could consider writing a Javascript function that converts an XDM map to a JS object, and calling this function.

It would then look something like:

<xsl:variable name="map" as="map(*)">
  <xsl:map>
    <xsl:map-entry key="'subject'" select="'SPARQLBuilder.SelectBuilder.var(''child'')'"/>
    <xsl:map-entry key="'predicate'" select="'SPARQLBuilder.SelectBuilder.var(''' || $predicate || ''''"/>,
    <xsl:map-entry key="'object'" select="'SPARQLBuilder.SelectBuilder.var(''whatever'')'"/>
 </xsl:map>
</xsl:variable>
<xsl:variable name="bgp" select="my:map-to-object($map)"/>

The main advantage is it avoids the dynamic eval. But getting the single and double quotes right is a bit of a nightmare.

Michael Kay
Saxonica

> On 4 Sep 2020, at 22:53, Martynas Jusevičius <martynas-tyFqBaoSXPC1Z/[email protected]> wrote:
> 
> Right, the attribute is a leftover from the Saxon-CE code... I found
> this snippet somewhere, I think the intention is to be able to use the
> attribute value template to inject values. But I can see that || in
> XSLT 3 does pretty much the same.
> 
> This code is calling methods on a JS library which builds a SPARQL
> query string in the end. It all works fine through ixsl:call(), it's
> just the object creation that requires ixsl:eval().
> 
> On Fri, Sep 4, 2020 at 11:45 PM Michael Kay <mike-JkSD5nQpfvpWk0Htik3J/[email protected]> wrote:
>> 
>> I can't see why you want to create an attribute in order to extract its string value. Why not just construct the string in the first place?
>> 
>> <xsl:variable name="js-statement" as="xs:string"
>> select="{ subject:  SPARQLBuilder.SelectBuilder.var('child'),
>>                predicate: SPARQLBuilder.SelectBuilder.var(' || $predicate || '),
>>                object: SPARQLBuilder.SelectBuilder.var('whatever') }"/>
>> 
>> Apart from that, if you really need to write the application by generating Javascript dynamically and then evaluating it, then I don't think it's going to much simpler than this. But I can't really judge whether that is actually the right design.
>> 
>> Michael Kay
>> Saxonica
>> 
>> 
>>> "
>>> select="ixsl:eval()"/>
>> 
>>> On 4 Sep 2020, at 21:39, Martynas Jusevičius <martynas-tyFqBaoSXPC1Z/[email protected]> wrote:
>>> 
>>> Hi,
>>> 
>>> Is there a quicker/cleaner way to create a JSON object and store it in
>>> a variable than this?
>>> 
>>>       <xsl:variable name="js-statement" as="element()">
>>>           <root statement="{{ subject:
>>> SPARQLBuilder.SelectBuilder.var('child'), predicate:
>>> SPARQLBuilder.SelectBuilder.var('{$predicate}'), object:
>>> SPARQLBuilder.SelectBuilder.var('whatever') }}"/>
>>>       </xsl:variable>
>>>       <xsl:variable name="bgp"
>>> select="ixsl:eval(string($js-statement/@statement))"/>
>>> 
>>> $bgp is later being used like this:
>>> 
>>> 
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>> 
>> 
>> 
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> 
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