Automatic and Explicit Context Updates

Automatic and explicit context updates are both supported context management methods.

Automatic updates – use data that is passed from another tile when a navigation action occurs. You can pass BO attributes, references to context or global context data, or to free text. Use $_context.<attribute> to refer to an existing local context attribute, and $_global.<attribute> for a global context attribute. This example shows how context parameters are passed when the navigate action is triggered. The target tile’s (TileB) local context is updated with the two values: a free text and a value coming from a binding:

<UIElement type="button">
  <P pid="text" value="Go" />
  <P pid="halign" value="center" />
  <Event eventId="onClick">
    <Action actionId="navigate">
     <!--Context receiver – the target tile which receives the context upon navigating to it -->
      <P pid="target" value="TileB" />     
     <!-- Keys and values to be passed to the target Tile's local context -->
	 <!-- The freetext value "Tablet" is passed for the key "type" -->
      <P pid="type" value="Tablet" />
	 <!-- The movie title coming from the binding MovieTitles is passed for the key "movie" -->
	  <P pid="movie" value="{$MovieTitles.Name}"	  
    </Action>
  </Event>
</UIElement>

Explicit updates – use the updateContext action. Use updateContext to update the local context of tiles that appear on the same screen, where navigation is impossible. iPad apps generally update a tile's local context explicitly.
You must specify the target tile (the receiver) in the same way as for automatic updates. Similarly, define the key-value pairs to be passed to the target tile as properties. You can pass BO attributes, references to local or global context data, or to free text. Use $_context.<attribute> to refer to an existing local context attribute, and $_global.<attribute> for a global context attribute. To pass the same objects to several different tiles, add a new updateContext action for every tile and repeat the context parameters. This example demonstrates how to bind the updateContext to the onClick event of a button. When the device user taps the button, the Tile3 target tiles’s context is updated for the “platform” and “type” keys.
```
<UIElement type="button">
 
 
 <Event eventId="onClick">
 <Action actionId="updateContext">
 <!—Context receiver – the target tile which receives the context-->
 
 <!—the key and value to be updated -->
 
 
 <!—the key and value to be updated – value is free text in this case-->
 
 </Action>
 </Event>
</UIElement>
```