Disable validation, if the current UIInput component has a null or empty value

Question

I need to validate a length of the value held by a UIInput component only if the value of that UIInput component is either null or an empty.

The length validator - <f:validateLength> should be skipped / bypassed, in case the value is null or empty.

I have tried the following approach with no success.

<p:inputTextarea id="address" autoResize="false" value="#{testManagedBean.address}" maxlength="1000" minQueryLength="10" cols="35" rows="7">
    <f:validateLength minimum="5" maximum="1000" disabled="#{empty testManagedBean.address}"/>
</p:inputTextarea>

<p:message for="address" display="both" showSummary="false"/>
<p:commandButton value="Submit" actionListener="#{testManagedBean.action}"/>

The bean:

@ManagedBean
@ViewScoped
public final class TestManagedBean implements Serializable
{
    private String address;
    private static final long serialVersionUID = 1L;

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public void action() {
        System.out.println("action() called.");
    }
}

This field - "address" is actually optional but if some users provide an input then, it should contain minimum of five characters in length.

EDIT:

I'm using disabled="#{empty param['form:address']}" to disable the validator, when the UIInput component has a null or empty value (not to dig further for a better way as this works anyway).

By putting validaateLength you're making it as required field. The other option you have is to validate this on server side in your action method. — Makky, Jun 18 '14 at 14:05

score 2 · Answer 1 · answered Jun 18 '14 at 22:14

No need for OmniFaces: you can create your own validator. You have to create a class that implements the javax.faces.validator.Validator interface, overrides the validate() method, and call it in your xhtml page. An alternative would be:

<p:inputTextarea id="address" autoResize="false" value="#{testManagedBean.address}" maxlength="1000" minQueryLength="10" cols="35" rows="7">
  <f:validator validatorId="myValidator"/>
</p:inputTextarea>

The validator class:

@FacesValidator("myValidator")
public class MyValidator Validator{

  @Override
  public void validate(FacesContext context, UIComponent component, Object value) 
        throws ValidatorException {
    String myValue = value.toString();
    if(myValue != null && !myValue.isEmpty() && (myValue.length() <= 5 || myValue.length() >= 1000)){
      throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_ERROR,
          "MyValidator Error: ", 
          "This error appears if your input has less than 5 chars or more than 1000."));
    }
  }
}

A custom validator is the last stage. I will use a custom validator, if I find no in-built way :) — Tiny, Jun 19 '14 at 15:24

score 1 · Accepted Answer · answered Jun 18 '14 at 22:27

1

You're on the right track, but you're not pulling the value off the component properly.

Bind the component to the page scope and retrieve the value like so:

<p:inputTextarea id="address" binding="#{theAddress}" autoResize="false" value="#{testManagedBean.address}" maxlength="1000" minQueryLength="10" cols="35" rows="7">
    <f:validateLength minimum="5" maximum="1000" disabled="#{empty theAddress.getSubmittedValue()}"/>
</p:inputTextarea>

Your current approach requires the textArea's value to be written to the backing bean. This can't happen until validation occurs (remember: testManagedBean.address is available only after successful validation); you're expecting that same value during validation: catch 22.

answered Jun 18 '14 at 22:27

kolossus

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Sorry, nothing new happens by using `disabled="#{empty theAddress.getSubmittedValue()}"`. `theAddress.getSubmittedValue()` always remains empty. – Tiny Jun 19 '14 at 14:02
@Tiny - that's weird. Try a different condition: `#{theAddress.isLocalValueSet()}`. This returns a boolean. – kolossus Jun 19 '14 at 15:08
`#{theAddress.isLocalValueSet()}` returns `true` even though `` is left blank (no input is provided to ``). – Tiny Jun 19 '14 at 15:21
The validator was rightfully disabled, when I used `disabled="#{empty param['form:address']}"`. It is still inappropriate to depend directly upon request parameters. – Tiny Jun 19 '14 at 18:05
1

@Tiny - I believe the reason the empty text is failing to validate properly is related to : http://stackoverflow.com/q/14607439/1530938 – kolossus Jun 20 '14 at 14:45

Disable validation, if the current UIInput component has a null or empty value

2 Answers2