Package org.apache.tapestry5.services

## Interface PersistentFieldStrategy

- All Known Subinterfaces:
    `ClientPersistentFieldStorage`
  All Known Implementing Classes:
    `AbstractSessionPersistentFieldStrategy`, `ClientPersistentFieldStorageImpl`, `ClientPersistentFieldStrategy`, `EntityPersistentFieldStrategy`, `EntityPersistentFieldStrategy`, `FlashPersistentFieldStrategy`, `SessionPersistentFieldStrategy`

      public interface PersistentFieldStrategy

  Defines how changes to fields (within components, within pages) may have their values persisted between requests. Different implementations store the field values in the session, on the client, or elsewhere.

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `discardChanges​(java.lang.String pageName)` | Discards any saved changes for the name page.
    `java.util.Collection<PersistentFieldChange>` | `gatherFieldChanges​(java.lang.String pageName)` | Finds all persistent changes previously stored for the named page (for the current active session or client).
    `void` | `postChange​(java.lang.String pageName, java.lang.String componentId, java.lang.String fieldName, java.lang.Object newValue)` | Posts a change of a persistent property.

- - ### Method Detail

    - #### postChange

          void postChange​(java.lang.String pageName,
                          java.lang.String componentId,
                          java.lang.String fieldName,
                          java.lang.Object newValue)

      Posts a change of a persistent property.
      Parameters:
        `pageName` - the name of the page containing the component
        `componentId` - the nested id path of the component (or null for the page's root component)
        `fieldName` - the name of the field whose persistent value has changed
        `newValue` - the new value for the field, possibly null

    - #### gatherFieldChanges

          java.util.Collection<PersistentFieldChange> gatherFieldChanges​(java.lang.String pageName)

      Finds all persistent changes previously stored for the named page (for the current active session or client).

    - #### discardChanges

          void discardChanges​(java.lang.String pageName)

      Discards any saved changes for the name page. There is no expectation that data already gathered from the strategy and presumably dumped into component instance fields will be affected, but future field access (within this request or a later one) will show no data for the indicated page.
      Parameters:
        `pageName` - logical name of page whose field persistent data should be discarded