AddTopElement (XmlDoc function)

Add new top Element to XmlDoc

AddTopElement is a member of the XmlDoc class.

This callable function adds an Element node as the new top-level element of the XmlDoc that is the object method. This makes all the former children of the XmlDoc Root node become children of the new element. AddTopElement also lets you specify the elementNamespace URI for the added element.

Syntax

  [%nod =] doc:AddTopElement(elementName, [URI] -
     [,MoveNamespace=boolean])

Syntax Terms

%nod

If specified, an XmlNode that is set to point to the new top Element node that is added.

doc

An XmlDoc object variable.

elementName

The name (a Unicode string) to be given to the added Element. If the name is prefixed, a URI argument must be provided. The name must conform to the XML syntax rules for an element name; the maximum length of each of the prefix part and local name part is 127 characters (100 characters prior to version 7.7 of Janus SOAP).

URI

This optional, Unicode string, argument defaults to the null string:

• If elementName contains a prefix, then URI specifies the URI (Uniform Resource Identifier) associated with that prefix for the element, so it must be a non-null string that is a valid URI.
• If elementName does not contain a prefix, URI must be omitted or must be the null string. This rule means that this URI argument is more restrictive than the URI argument of the AddElement method (??AddElement).

MoveNamespace=boolean

This optional, name required argument is used to avoid a redundant namespace declaration on the old top element of the XmlDoc. If MoveNamespace=True and a URI argument (with a non-null string) is provided, then if the "old" top element contains a namespace declaration which is the same as the declaration inserted due to the URI argument, the declaration is deleted from the old top element. Note: You should use MoveNamespace=True only when some consumer of the XML document cares about not having the redundant declaration. This would be an unusual situation, because the information content of the document does not change. Using MoveNamespace=True might trigger a scan of the entire XmlDoc, which AddTopElement does not normally do.

Usage Notes

• If a URI argument is specified, the XmlDoc's Namespace property must be On.
• When you need to change the structure of an XML document and that need can be accomplished with AddTopElement, it is a more efficient approach than using AddSubtree. See the example in “Examples,” below.

Examples

The following request makes a copy of an XML document, then adds “SOAP wrappers” to it:

    Begin
    %doc is Object XmlDoc
    %doc2 is Object XmlDoc
    %doc = New

    %doc:LoadXml('<top><a><b></b></a></top>')
    Call %doc:Print
    Print '*********************'

    %doc2 = %doc:DeepCopy
    %doc2:AddTopElement('soap:Body', -
     'http://schemas.xmlsoap.org/soap/envelope/')
    %doc2:AddTopElement('soap:Envelope', -
     'http://schemas.xmlsoap.org/soap/envelope/')

    Call %doc2:Print
    End

The result (with new top element lines wrapped due to space limitations) is:

    <top>
       <a>
          <b/>
       </a>
    </top>
    <soap:Envelope
    xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
       <soap&colon.Body
       xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
          <top>
             <a>
                <b/>
             </a>
          </top>
       </soap:Body>
    </soap:Envelope>

In the example:

• The order of the AddTopElement invocations is the reverse of the final order of the elements, that is, the second invocation creates the first element in the final document.
• If you have no need to preserve the original XmlDoc, then both AddTopElement invocations can use %doc as the object method, and the DeepCopy can be omitted.
• The redundant namespace declaration on the soap&colon.Body element above would be deleted if the MoveNamespace=True argument is used, although usually the redundant declaration is acceptable and MoveNamespace should be avoided.

Request-Cancellation Errors

• Argument elementName violates the rules for an XML element name.
• elementName is prefixed, but the XmlDoc Namespace property is None.
• elementName is prefixed and Namespace is On, but URI is missing.
• URI is invalid.
• URI is present, but the Namespace property is not On, or, URI is the null string and elementName is prefixed.
• Insufficient free space exists in CCATEMP.

See Also

• For more information about namespace declarations, see ?? refid=namsp..
• For more information about URIs, see ?? refid=nsuri..
• AddElement and ??InsertElementBefore also add an Element node. AddElement adds an Element as the last child of the node pointed to by the method object; InsertElementBefore adds an Element as the immediately preceding sibling of the node pointed to by the method object.
• These methods are useful for working with namespaces:
  • AddNamespace
  • SelectionNamespace