The arc:null keyword checks that an attribute does not exist in the specified item.

Parameters

• item: The item to check. If not specified, the default output item is used.
• attr: The name of the attribute to check.
• action: The action to perform if the expression evaluates to true. Allowed values: break, continue.

Control Attributes

None

Example

Define missing title attributes.

<arc:call op="fileListDir" output="out">
  <arc:null attr="filename">
    <arc:set attr="title" value="Unnamed File"/>
    <arc:else>
      <arc:set attr="title" value="[filename]"/>
    </arc:else>
  </arc:null>
  <arc:push title="[title]">
  [out.file:*] 
  </arc:push>
</arc:call>

See Also

• arc:else: Create a block which is executed if the condition is not satisfied.