How do I call a function in xquery - xquery

Question

Xml format is like:
<outer_element>
<list>
<leaf name="abc">
<D:a value=""/>
<D:b value="2"/>
<D:c value="3"/>
<D:text_enabled value="true"/>
</leaf>
<leaf name="xyz">
....
</leaf>
</list>
</outer_element>
This is just the structure, below is the xquery for removing certain portion of the xml: to remove leafs that have D:text_enabled value="true"
declare namespace my="my.uri";
declare variable $flag;
declare function my:isEnabled($node as node()) as xs:boolean
{
let $flag :=
for $child in $node/node()
return string-join(if(name($child) eq "D:text_enabled" and $child/#value eq "true") then "true" else "false" , " ")
return contains($flag,"true")
};
declare function my:filtering($node as node())
{
typeswitch ($node)
case element()
return
if (string(local-name($node)) = "import")
then
()
else
if(string(local-name($node)) = "leaf" and $flag=isEnabled($node) )
then
()
else
element
{
node-name($node)
} {
$node/#*
,
for $child in $node/node()
return my:filtering($child )
}
default
return
if (string(local-name($node)) = "import")
then
()
else
$node
};
let $input := doc("input.xml")
return
for $elem in $input/*
return
my:filtering($elem)
Errors I am getting are:
XPST0003: XQuery syntax error in #...eclare variable $flag; declare#:
Expected ':=' or 'external' in variable declaration
XPST0008: XQuery static error in #... = "leaf" and $flag=isEnabled#:
Variable $flag has not been declared
Static error(s) in query

Answer 1

This is nothing to do with calling a function.
A global variable must either be declared external, in which case a value is supplied by the calling application:
declare variable $flag external;
or it must be initialised to a value:
declare variable $flag := false();
But actually, you're not using the global variable at all, so you can just delete the declaration. You've got another quite separate local variable called $flag, that doesn't need a global declaration.
Some further suggestions:
if (string(local-name($node)) = "import") is better written as `if ($node[self::*:import])
As far as I can tell, the code
let $flag :=
for $child in $node/node()
return string-join(if(name($child) eq "D:text_enabled" and $child/#value eq "true") then "true" else "false" , " ")
return contains($flag,"true")
can probably be written as
exists($node/D:text_enabled[#value eq "true"])