Configuring the Proposals in the Content Completion Assistant

Oxygen XML Editor gathers information from the associated schemas (DTDs, XML Schema, RelaxNG) to determine the proposals that appear in the Content Completion Assistant. Oxygen XML Editor also includes support that allows you to configure the possible attribute or element values for the proposals. To do so, a configuration file can be used, along with the associated schema, to add or replace possible values for attributes or elements that are proposed in the Content Completion Assistant. An example of a specific use-case is if you want the Content Completion Assistant to propose several possible values for the language code whenever you use an xml:lang attribute.

To configure content completion proposals, follow these steps:

Create a new resources folder (if it does not already exist) in the frameworks directory for the document type. For instance: OXYGEN_INSTALL_DIR/frameworks/dita/resources.
Open the Preferences dialog box and go to Document Type Association. Edit the document type configuration for your XML vocabulary, and in the Classpath tab add a link to that resources folder.
Use the New document wizard to create a configuration file using the Content Completion Configuration file template.
Make the appropriate changes to your custom configuration file. The file template includes details about how each element and attribute is used in the configuration file.
Save the file in the resources folder, using the fixed name: cc_value_config.xml.
Re-open the application and open an XML document. In the Content Completion Assistant you should see your customizations.

The Configuration File

The configuration file is composed of a series of match instructions that will match either an element or an attribute name. A new value is specified inside one or more item elements, which are grouped inside an items element. The behavior of the items element is specified with the help of the action attribute, which can have any of the following values:

append - Adds new values to appear in the proposals list (default value).
addIfEmpty - Adds new values to the proposals list, only if no other values are contributed by the schema.
replace - Replaces the values contributed by the schema with new values to appear in the proposals list.

The values in the configuration file can be specified either directly or by calling an external XSLT file that will extract data from any external source.

Example - Specifying Values Directly

<!-- Replaces the values for an element with the local name "lg", from the given namespace -->
<match elementName="lg" elementNS="http://www.oxygenxml.com/ns/samples">
    <items action="replace">
        <item value="stanza"/>
        <item value="refrain"/>
    </items>
</match>

<!-- Adds two values for an attribute with the local name "type", from any namespace -->
<match attributeName="type">
    <items>
        <item value="stanza"/>
        <item value="refrain"/>
    </items>
</match>

Example - Calling an External XSLT Script

<xslt href="../xsl/get_values_from_db.xsl" useCache="false" action="replace"/>

In this example, the get_values_from_db.xsl is executed in order to extract values from a database.

Note: A comprehensive XSLT sample is included in the Content Completion Configuration file template.

Configuring Proposals in the Context for which the Content Completion was Invoked

A more complex scenario for configuring the content completion proposals would be if you want to choose the possible values to provide, depending on the context of the element in which the content completion was invoked.

Suppose that you want to propose certain possible values for one property (for example, color) and other values for another property (for example, shape). If the property represents a color, then the values should represent applicable colors, while if the property represents a shape, then the values should represent applicable shapes. See the following code snippets:

Your main document:

<sampleArticle>
  <!-- The possible values for @value should be "red" and "blue" -->
  <property name="color" value=""/>
  <!-- The possible values for @value should be "square" and "rectangle" -->
  <property name="shape" value=""/>
</sampleArticle>

The content completion configuration file:

<config xmlns="http://www.oxygenxml.com/ns/ccfilter/config">
    <match elementName="property" attributeName="value">
      <xslt href="get_values.xsl" useCache="false" action="replace"/>
    </match>
</config>

The stylesheet that defines the possible values based on the context of the property on which the content completion was invoked:

<xsl:stylesheet 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:saxon="http://saxon.sf.net/"
  exclude-result-prefixes="xs"
  version="2.0">
  
  <xsl:param name="documentSystemID" as="xs:string"></xsl:param>
  <xsl:param name="contextElementXPathExpression" as="xs:string"></xsl:param>
  
  <xsl:template name="start">
    <xsl:apply-templates select="doc($documentSystemID)"/>
  </xsl:template>
  
  <xsl:template match="/">
    <xsl:variable name="propertyElement" 
        select="saxon:eval(saxon:expression($contextElementXPathExpression, ./*))"/>
    
    <items>
      <xsl:if test="$propertyElement/@name = 'color'">
        <item value='red'/>
        <item value='blue'/>  
      </xsl:if>
      <xsl:if test="$propertyElement/@name = 'shape'">
        <item value='rectangle'/>
        <item value='square'/>  
      </xsl:if>
    </items>
  </xsl:template>
</xsl:stylesheet>

The contextElementXPathExpression parameter will be bound to an XPath expression that identifies the element in the context for which the content completion was invoked.