Package org.apache.tapestry5

## Interface NullFieldStrategy

- All Known Implementing Classes:
    `DefaultNullFieldStrategy`, `ZeroNullFieldStrategy`

      public interface NullFieldStrategy

  Defines a strategy, used by `Field` components such as `TextField`, to handle the case where either the server-side value to be sent (as a string) to the client, or the client-side string passed back up to the server, is null or blank.
  See Also:
    `NullFieldStrategySource`

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `String` | `replaceFromClient()` | Provides a replacement value for a null or blank string passed from the client to the server as part of a form submission.
    `Object` | `replaceToClient()` | Provides a replacement value for null, when converting the server-side object to a client-side string.

- - ### Method Detail

    - #### replaceToClient

          Object replaceToClient()

      Provides a replacement value for null, when converting the server-side object to a client-side string. The replacement value, if non-null, will be passed to `Translator.toClient(Object)`.

    - #### replaceFromClient

          String replaceFromClient()

      Provides a replacement value for a null or blank string passed from the client to the server as part of a form submission. This replacement value will be passed to `Translator.parseClient(Field, String, String)` as if it were the value supplied by the user.
      Returns:
        replacement value (this must not be null)