DOM Create XML element

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4D v20 R7


DOM Create XML element ( elementRef ; xPath {; attribName ; attrValue} {; attribName2 ; attrValue2 ; ... ; attribNameN ; attrValueN} ) -> Function result

Parameter	Type	Description
elementRef	String	Root XML element reference
xPath	Text	XPath path of the XML element to create
attribName	String	Attribute to set
attrValue	String, Boolean, Longint, Real, Time, Date	New attribute value
Function result	String	Reference of the created XML element

Description

The DOM Create XML element command creates a new element in the XML element elementRef in the path set by the xPath parameter and adds attributes to it if necessary.

Pass the root element reference in elementRef (created, for example, using the DOM Create XML Ref command).

In xPath, pass the path of the element to create, expressed using the XPath notation (for more information, see the Support of XPath notation (DOM) section). The following path expressions are supported:

Expression	Action
/	Designates the root node (absolute path)
para[1]	Designates the first para child of the context node
para[last()]	Designates the last para child of the context node

Compatibility Note: Starting with v18 R3, the XPath implementation in 4D is more compliant. For compatibility reasons, the previous non-standard implementation is maintained by default in converted databases. If you want to benefit from the extended features in your converted databases, you need to select the Use standard XPath compatibility option of the Compatibility page.

It is possible to pass a simple item name directly in the xPath parameter in order to create a sub-item from the current item (see example 3).

If any path elements do not exist, they are created. If path elements already exist, a new node is added.

Note: If you have defined one or more namespaces for the tree set using elementRef (see the DOM Create XML Ref command), you must precede the xPath parameter with the namespace to be used (for example, “MyNameSpace:MyElement”).

You can pass attribute/attribute value pairs (in the form of variables, fields or literal values) in the optional attrName and attrValue parameters. You can pass as many pairs as you want.

The attrValue parameter can be of the text type or another type (Boolean, integer, real, date or time). If you pass a value other than text, 4D handles its conversion to text, according to the following principles:

Type	Example of converted value
Boolean	"true" or "false"
Integer	"123456"
Real	"12.34" (the decimal separator is always ".")
Date	"2006-12-04T00:00:00Z" (RFC 3339 standard)
Time	"5233" (number of seconds)

The command returns the XML reference of the element created as a result.

Example 1

We want to create the following element:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<RootElement>
   <Elem1>
      <Elem2>
         <Elem3> </Elem3>
         <Elem3> </Elem3>
      </Elem2>
   </Elem1>
</RootElement>

To do so, simply write:

 C_TEXT(vRootRef;vElemRef)

 vRootRef:=DOM Create XML Ref("RootElement")

 vxPath:="/RootElement/Elem1/Elem2/Elem3[2]"

 vElemRef:=DOM Create XML element(vRootRef;vxPath)

Example 2

We want to create the following element (containing attributes):

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<RootElement>
   <Elem1>
      <Elem2>
         <Elem3 Font=Verdana Size=10> </Elem3>
         <Elem3 Font=Verdana Size=8> </Elem3>
      </Elem2>
   </Elem1>
</RootElement>

To do so, simply write:

 C_TEXT(vRootRef;vElemRef)

 C_TEXT($aAttrName1;$aAttrName2;$aAttrVal1;$aAttrVal2;$aAttrVal3)</p><p>$aAttrName1:="Font"

 $aAttrName2:="Size"

 $aAttrVal1:="Verdana"

 $aAttrVal2:="10"

 $aAttrVal3:="8"

 

 vRootRef:=DOM Create XML Ref("RootElement")

 vxPath:="/RootElement/Elem1/Elem2/Elem3"

 vElemRef:=DOM Create XML element(vRootRef;vxPath;$aAttrName1;$aAttrVal1;$aAttrName2;$aAttrVal2)

 vElemRef:=DOM Create XML element(vRootRef;vxPath;$aAttrName1;$aAttrVal1;$aAttrName2;$aAttrVal3)

If you want to insert an element afterwards, you can write:

 vxPath:="/RootElement/Elem1/Elem2/Elem3[2]"

 vElemRef:=DOM Create XML element(vRootRef;vxPath;"Font";"Arial")

You have then:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<RootElement>
   <Elem1>
      <Elem2>
         <Elem3 Font=Verdana Size=10> </Elem3>
         <Elem3 Font=Arial> </Elem3>
         <Elem3 Font=Verdana Size=8> </Elem3>
      </Elem2>
   </Elem1>
</RootElement>

Example 3

We want to create and export the following structure:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<Root>
   <Elem1>Hello</Elem1>
</Root>

We want to use the syntax based on a simple item name. To do this, simply write:

 C_TEXT($root)

 C_TEXT($ref1)

 

 $root:=DOM Create XML Ref("Root")

 $ref1:=DOM Create XML element($root;"Elem1")

 DOM SET XML ELEMENT VALUE($ref1;"Hello")

 DOM EXPORT TO FILE($root;"mydoc.xml")

 DOM CLOSE XML($root)

System variables and sets

If the command was executed correctly, the system variable OK is set to 1. Otherwise, it is set to 0 and an error is generated.

Error management

An error is generated when:

The root element reference is invalid.
The name of the element to create is invalid (for example, if it starts with a number).