Retrieving value of JSF input field without managed bean property [closed]

问题

I would like to retrieve the value of JSF input box in a managed bean action method, without it being associated with any managed bean property. E.g.

<p:inputText id="txtuserid" value="" />

My use case is that in my application I will like to prompt user here and there for passwords for every DML operations, and therefore like to have a password and comment related fields on each of my UI, and the remarks needs to be saved in a common table for audit purpose.

How can I achieve this?

回答1:

Just do the same as JSF is doing under the covers: grabbing the HTTP request parameter. If you're familiar with basic HTML, you know that every HTML input element sends its name=value pair as HTTP request parameter.

Given a

<h:form id="formId">
    <p:inputText id="userId" /> <!-- Note: no value attribute at all, also no empty string! -->
    ...
    <p:commandButton value="submit" action="#{bean.submit}" />
</h:form>

which generates basically the following HTML

<form id="formId" name="formId">
    <input type="text" name="formId:userId" ... />
    ...
    <button type="submit" ...>submit</button>
</form>

you could grab it as follows from ExternalContext#getRequestParameterMap():

public void submit() {
    ExternalContext ec = FacesContext.getCurrentInstance().getExternalContext();
    String userId = ec.getRequestParameterMap().get("formId:userId");
    // ...
}

Don't forget to manually convert and validate it if necessary, like as JSF is doing under the covers. In other words, just repeat the JSF's job by writing additional code so that your code is not DRY :)

回答2:

If the remarks property is independent of any entities, so it will depend only as a property, to a managed-bean sessionScoped or requestScoped according to your needs, to to what you want. If you want that this property to be independant to any Java-Beans, so you can use the attirbute binding of the inputText tag.

To do that, see here at the good response of M. @BalusC : How does the 'binding' attribute work in JSF? When and how should it be used?

And see also: The reasons to use binding in a JSF form

来源：https://stackoverflow.com/questions/19002570/retrieving-value-of-jsf-input-field-without-managed-bean-property

标签

jsf

input

managed-bean