How to use ajax with Primefaces components programmatically

Question

I'm trying to create Primefaces UIComponents programmatically and somehow I'm not able to get the data to the Backing Bean. Not sure if it's the Ajax or the value I set for the InputText. My code that I want to write programmatically:

<p:inputText id="id_test" value="#{myBean.value}">
    <p:ajax />
</p:inputText>

This is how I tried to solve the problem:

private String value; // Getter&Setter


public void buildComponent(){
    FacesContext fc = FacesContext.getCurrentInstance();
    Application ap = fc.getApplication();

    InputText inputText = (InputText) ap.createComponent(fc, "org.primefaces.component.InputText", "org.primefaces.component.InputTextRenderer")
    inputText.setValue(value);
    inputText.setId("id_test");

    AjaxBehavior ajaxBehavior = (AjaxBehavior) ap.createBehavior(AjaxBehavior.BEHAVIOR_ID);
    inputText.addClientBehavior(inputText.getDefaultEventName(), behavior);
}

You have set a concrete String value to `InputText.setValue()`, but you need to provide an actual ValueExpression. — Selaron, Nov 26 '18 at 12:50
So the actual problem solved here does not relate to Primefaces nor AJAX and could be reduced to a question duplicate to https://stackoverflow.com/questions/3510614/how-to-create-dynamic-jsf-form-fields — Selaron, Nov 26 '18 at 13:23
Not a problem, wasn't a judgement but a conclusion only. We developers keep searching into the most complex directions even if the root cause is as simple as a typo ;-) — Selaron, Nov 27 '18 at 15:29

score 2 · Accepted Answer · answered Nov 26 '18 at 13:05

You will need to create a ValueExpression that resolves to your bean property. How else should your dynamic input know where to send input values to?

Instead of:

inputText.setValue(value);

Do this:

ExpressionFactory expressionFactory = FacesContext.getCurrentInstance()
  .getApplication().getExpressionFactory();
ValueExpression veBinding = expressionFactory.createValueExpression("#{myBean.value}", String.class);
inputText.setValueExpression("value", veBinding);

score 1 · Answer 2 · answered Nov 26 '18 at 12:41

1

I'm not sure what you intend to do, but it might be better to render the component dynamically instead of creating it. Something like that:

<p:inputText id="id_test" value="#{myBean.value}" rendered="#{myBean.isSomeCondition">
    <p:ajax />
</p:inputText>

or

<p:inputText id="id_test" value="#{myBean.value}" rendered="#{myBean.value != 'whatever'">
    <p:ajax />
</p:inputText>

answered Nov 26 '18 at 12:41

Cleo

181
6

Thanks but the problem I'm facing is that I don't know the number or type of the input components that I need. – JavaFan Nov 26 '18 at 12:51

How to use ajax with Primefaces components programmatically

2 Answers2