How to receive xml nodes inside a time range by using xquery - date

Question

I have an xml with something like that inside
<SFEvents>
<EventList>
<Event>
<ID>1111</ID>
<Type>Measurement</Type>
<TimeStamp>2015-09-28T09:50:27.514</TimeStamp>
<Space>Main_area</Space>
<SourceID>Thermometer_3</SourceID>
<Content>
<Measurement>
<!-- From B2MML standard (OpSegmentDataType) -->
<ID/>
<Description>Temperature of a power resistance</Description>
<Value>
<ValueString>100</ValueString>
<UnitOfMeasure>oC</UnitOfMeasure>
</Value>
</Measurement>
</Content>
</Event>
<Event>..</Event>
...
</EventList>
with many events and I currently try to receive with xquery all the Event nodes that have their Timestamp inside a time range
I use this code
all_xmls_String=session.execute("xquery for $b in doc('CIDEMdb/CIDEM.xml')
let $date_string as xs:string :=$b/SFEvents/EventList/Event/TimeStamp/data()
let $date as xs:dateTime := xs:dateTime($date_string)
where $date ge xs:dateTime('"+startdate+"') and $date le
xs:dateTime('"+enddate+"') return $b/SFEvents/EventList");
but I receive this error
Cannot cast xs:untypedAtomic+ to xs:string: ("2015-09-28T09:50:27.514", ...).
Any idea?

Answer 1

The problem is that you are iterating over the EventList document, which has a cardinality of 1, while selecting $b/SFEvents/EventList/Event/TimeStamp/data(), a sequence of TimeStamp values, and assigning it to a variable that expects a single value. Your query also returns an EventList, but you say you want to return Events.
There are several ways to do this, but the easiest way given your existing query it to simply iterate over the Event elements instead, select the single TimeStamp value, and then return the selected Events.
for $b in doc('CIDEMdb/CIDEM.xml')//SFEvents/EventList/Event
let $date_string as xs:string :=$b/TimeStamp/data()
let $date as xs:dateTime := xs:dateTime($date_string)
where $date ge xs:dateTime('"+startdate+"') and $date le xs:dateTime('"+enddate+"')
return $b