如果f：viewParam为空，则重定向 [英] Redirect if a f:viewParam is empty

问题描述

Сan如果 f：viewParam 为空，我做一个重定向（或错误）

Сan I do a redirect (or error) if a f:viewParam is empty?

<f:metadata>
    <f:viewParam name="accountId" value="#{accountMB.id}"/>
</f:metadata>

当我添加 required =true ， 什么都没发生。有什么选择？

When I add required="true", nothing happens. What are the options?

推荐答案

当我添加 =true，没有任何反应

When I add required="true", nothing happens

你需要 ; h：message（s）> 显示与给定（输入）组件相关联的面部消息。您可能已经知道如何执行< h：inputText> 。您可以为< f：viewParam> 完全一样。

You need <h:message(s)> to show faces messages associated with a given (input) component. You probably already know how to do that for <h:inputText>. You can do exactly the same for <f:viewParam>.

<f:metadata>
    <f:viewParam id="foo" ... required="true" />
</f:metadata>
...
<h:message for="foo" />

---

---

Сan如果一个 f：viewParam 是空的，我做一个重定向（或错误）

Сan I do a redirect (or error) if a f:viewParam is empty?

不直接使用标准的JSF验证工具。您需要在< f：viewAction> 中手动执行作业（您需要确保您没有任何验证器/转换器，否则它不会因验证/转换错误而被调用;您也可以使用< f：event type =preRenderView> ）。

Not directly with standard JSF validation facilities. You'd need to do the job manually in <f:viewAction> (you need to make sure that you don't have any validators/converters on it, otherwise it wouldn't be invoked due to a validation/conversion error; you could alternatively use <f:event type="preRenderView">).

<f:metadata>
    <f:viewParam value="#{bean.foo}" />
    <f:viewAction action="#{bean.checkFoo}" />
</f:metadata>

public String checkFoo() {
    if (foo == null || foo.isEmpty()) {
        return "some.xhtml"; // Redirect to that page.
    } else {
        return null; // Stay on current page.
    }
}

发送HTTP错误可以如下完成（这示例发送HTTP 400错误）：

Sending a HTTP error can be done as below (this example sends a HTTP 400 error):

public void checkFoo() {
    if (foo == null || foo.isEmpty()) {
        FacesContext context = Facescontext.getCurrentInstance();
        context.getExternalContext().responseSendError(400, "Foo parameter is required");
        context.responseComplete();
    }
}

---

如果您碰巧使用JSF实用程序库 OmniFaces ，那么您可以使用 < o：viewParamValidationFailed> 标签用于非常目的，而不需要额外的后台bean逻辑

---

If you happen to use the JSF utility library OmniFaces, then you can use the <o:viewParamValidationFailed> tag for the very purpose without needing additional backing bean logic.

发送视图参数验证失败的重定向失败：

Sending a redirect on view param validation fail:

<f:metadata>
    <f:viewParam ... required="true">
        <o:viewParamValidationFailed sendRedirect="some.xhtml" />
    </f:viewParam>
</f:metadata>

在视图param验证失败时发送HTTP 400错误：

Sending a HTTP 400 error on view param validation fail:

<f:metadata>
    <f:viewParam ... required="true">
        <o:viewParamValidationFailed sendError="400" />
    </f:viewParam>
</f:metadata>

另请参见：

• 什么可以< f：metadata>，< f ：viewParam>和< f：viewAction>用于？



See also:

• What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?

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