| 4.3. Parameter Directions | ||
|---|---|---|
 | Chapter 4. Tapestry Components - A Primer |  |
| 4.3. Parameter Directions | ||
|---|---|---|
| | Chapter 4. Tapestry Components - A Primer | |
Components can not only read the values from the parameter binding properties but also update them. Components specify this ability for each parameter via the parameter-attribute called direction in the component specification. Parameter directions can be one of three different types from a usage stand-point.
![[Note]](common-images/note.png) | Note |
|---|---|
| The parameter directions are a little different from a specification stand-point which we will cover later. | |
The parameter binding property is only read, never updated.
... <span jwcid="@Insert" value="ognl:userName" /> ... |
The parameter binding property is only updated, never read.
...
<span jwcid="@Foreach" ... value="ognl:iterationValue">
...
</span>
... |
The parameter binding property is both read and updated.
... <input jwcid="@TextField" value="ognl:userName" /> ... |
| Note |
|---|---|
| Due to the nature of the bindings, out and in-out parameters can only have dynamic or inherited bindings. | |
| |  | |
| 4.2. Parameters and Bindings |  | 4.4. Formal and Informal Parameters |