drb-xquery 1.0.2

DRB xquery request

Xquery for DRB

This xquery module allows execute xquery on DRB nodes.

Using this module

To include this module into your project, the drb-xquery module shall be referenced into requirement.txt file, or the following pip line can be run:

pip install drb-xquery

Example for execute a query on xml node:

    node_file = DrbFileFactory().create("/path_xml_file/namefile.xml")
    node = XmlNodeFactory().create(node_file)

    # request node named 2A_Tile_ID with ns as namespace
    query = DrbXQuery("/ns:Level-2A_Tile_ID")
    result = query.execute(node)

Result is always a list of value or dynamic context

Example with external variables:

    # create the query from  String   
    query = DrbXQuery("declare variable $x external; "
                     "declare variable $y external := 5; $x+$y")

    list_var = {'x': 9, 'y': 12}

    result = query.execute(node, list_var)

    # result[0] == 21

Limitations and differences with W3C standard

The data() function return only the value of elt

for example :

 data(element root {element foo {"child"}, " parent" })

return in W3C standard:

child parent

return in this implementation:

parent

The infinity value is allowed for Decimal as for float: In W3C infinity is only allowed for float or double.

The type xs:double is identical to xs:float The type xs:long, xs:short, xs:byte are identical to xs:integer

Other limitations

Some types are not defined like: xs:anyURI xs:untypedAtomic ...

Some functions are not yet implemented like: yearMonthDuration deep-equal remove processing-instruction exactly-one ...

Some expressions are not (yet) implemented like: group by order by typeswitch treat as map and array are not defined too

Warning for user using drb java implementation of Xquery

When using positional predicates, you should be aware that the to keyword does not work as you might expect when used in predicates. If you want the first three products, it may be tempting to use the syntax:

doc("catalog.xml")/catalog/product[1 to 3]

However, this will raise an error[*] because the predicate evaluates to multiple numbers instead of a single one. You can, however, use the syntax:

doc("catalog.xml")/catalog/product[position() = (1 to 3)]

For compare function the result is only -1,0, 1 , in java thi function return a negative value that can be different to -1 or a positive value that represent a difference between the two string...