Calling/Sending Parameters to Xquery & Best Practice

 

To call an xquery stored in a file, you can use xdmp:invoke function.

you need to specify the file name and the parameters to send.

syntax

xdmp:invoke(
filepath as xs:string
[params as item()*]
[options as node()?]
) as item()*

for eg.

Invoking xquery file with parameters

xdmp:invoke("xqueryfilename.xqy", (xs:QName("parameter name1"), "parameter value",xs:QName("parameter name2"), "parameter value”))

Invoking xquery file without parameters

xdmp:invoke("xqueryfilename.xqy")

 

Invoking xquery file with a URI and namespace

Xquery file at URI http://marklogicsite.com/modules with filename xqueryfilename.xqy

Note – options should always be in xdmp:eval namespace

---------------------------------------------------

 xquery version "1.0-ml";
  declare namespace exns="example-namespace";
  declare variable $exns:docuriparam as xs:string external;
  fn:doc($exns:docuriparam)

---------------------------------------------------

It returns the document with the specified path.

---------------------------------------------------

xquery version "1.0-ml";
declare namespace exns="example-namespace";

xdmp:invoke("xqueryfilename.xqy",(xs:QName(“exns:docuriparam”), “modulename/xmldocname.xml”) , <options xmlns=”xdmp:eval”><modules>{xdmp:modules-database()}</modules><root>http://marklogicsite.com/modules</root></options>)

----------------------------------------------------

Here xdmp:modules-database() returns the ID of the modules database.

root is for root path of the modules. To return the current root path use xdmp:modules-root()

 

Best Practice regarding passing parameters to xquery.

If the xquery requires several parameters to be sent, its better to fragment all the parameters inside a single XML Node which in turn will get passed as a parameter. The xquery then in turn will process the node and xpath to get the parameter as and when required.

 

For eg. consider the following variables declaration in xquery.

-----------------------------------

xquery version "1.0-ml";

declare variable $employeeName as xs:string external;

declare variable $companyName as xs:string external;

declare variable $departmentName as xs:string external;

declare variable $registered as xs:string external;

declare variable $dateLastAccessed as xs:string external;

-----------------------------------

We can modify the above and use a single parameter to get all the details sought

-----------------------------------

xquery version "1.0-ml";

declare variable $parameters as xs:string external;

-----------------------------------

and the parameter value could be

-----------------------------------

<parameters>

<parameter><employeeName>empname</employeeName></parameter>


<parameter><companyName>compname</companyName></parameter>


<parameter><departmentName>dname</departmentName></parameter>


<parameter><registered>Yes</sortparam></registered>


<parameter><dateLastAccessed>2006-05-05</dateLastAccessed></parameter>


</parameters>

-----------------------------------

In the xquery you can xpath $parameters to get your value

for eg. $parameters//employeeName will get you the value of first parameter.

 

This makes the code better and passing the parameters will be clean and nice.