| Page State | ||
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 | Chapter 4. Tapestry Pages |  |
| Page State | ||
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| | Chapter 4. Tapestry Pages | |
Pages, and the components on them, have state. State is considered the set of values for the properties of the page.
In Tapestry, the lifespan of each property is very important. There are three lifespans:
Persistent. Changes the property are recorded and persist between request cycles. Persistent properties are restored when the page is next loaded. Persistent properties are specific to an individual user.
Transient. The property is set before the page is rendered and will be reset (to its default value) at the end of the current request cycle.
Dynamic. The property changes even while the page is rendered, but (like transient) the property is reset at the end of the current request cycle.
Persistent properties are things like the user's name, the product being displayed in an e-commerce application, etc. Transient properties are more commonly things needed just once, such as an error message. Dynamic properties are intimately tied to the rendering process ... for example, to display a list of items in an order, it may be necessary to have a dynamic property take the value of each line item in sequence, as part of a loop.
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| Chapter 4. Tapestry Pages |  | Persistent Page State |