validation - How to validate if at least one of multiple input fields is entered?

Question

I have a form with 3 fields, and submit button. when button clicked, if none is entered in 3 fields, throw validation message. If any one of the 3 fields are entered process the data and show results back in same page using data table. I am able to throw validation message for one field, but not for 2 fields or more.Here is my code. As well, if I have a long value that I need to pass, and validate how can i do that, since long value can not be validated as isEmpty() or isNull().

Here is my code, I want to use it with multiple fields and with fields that have long values get validated.

<h:inputText id="userName" value="#{user.userName}" required="true"
    requiredMessage="Please enter username" />

<h:inputText id="empId" value="#{user.empId}" required="true"
    requiredMessage="Please enter Employee Id" />

<h:inputText id="acctNm" value="#{user.acctNm}" required="true" 
    requiredMessage="Please enter Employee Id" />

Answer 1

Just let the required attribute of each field check the presence of the submitted value of the other fields. The submitted value is available in the parameter map #{param} by the client ID as key.

Here's a kickoff example:

<h:form id="form">
    <h:inputText id="field1" ... required="#{empty param['form:field2'] and empty param['form:field3']}" />
    <h:inputText id="field2" ... required="#{empty param['form:field1'] and empty param['form:field3']}" />
    <h:inputText id="field3" ... required="#{empty param['form:field1'] and empty param['form:field2']}" />
</h:form>

It gets only more ugly as the amount of fields grows.

Alternatively, you can use OmniFaces <o:validateOneOrMore>:

<h:form id="form">
    <h:inputText id="field1" ... />
    <h:inputText id="field2" ... />
    <h:inputText id="field3" ... />

    <o:validateOneOrMore id="oneOrMore" components="field1 field2 field3" />
    <h:message for="oneOrMore" />
</h:form>

Please note that performing validation in action method is bad design. You should use the standard JSF validation facilities for this such as requiered, validator, <f:validator> and/or <f:validateXxx>.