Confluence plugin: Show error message on current page

[Tobias Uhmann]

I am developing a Confluence plugin that has a web item which triggers an action that communicates with a web service. When receiving the response I redirect to another page.

When I receive an error or no response at all I want to stay on the page and show an error message. It's absolutely ok to reload the page for that.

My action class inherits from ConfluenceActionSupport. So, I tried using addActionError() and addActionMessage() but without success. The page gets reloaded but no message appears.

Here's my atlassian-plugin.xml :

<xwork name="translate-xwork" key="translate-xwork">
       <package name="translate-package" extends="default" namespace="/plugins/translate-package">
           <default-interceptor-ref name="defaultStack"/>
           <action name="translate-action" class="com.aoe.deepl.TranslateAction">
               <result name="success" type="redirect">${translatedPage.urlPath}</result>
               <result name="error" type="redirect">${page.urlPath}</result>
           </action>
       </package>
   </xwork>

What am I doing wrong? Don't the standard Confluence pages show error messages set this way? Do I have to write a custom velocity template for that? Is redirecting to the current page the wrong approach? Where can I find the documentation for the XML attributes, i.e. what can I specify for the type attribute instead of 'redirect'?

Update:

My problem is very similar to this one: https://community.developer.atlassian.com/t/how-to-show-user-message-in-confluenceactionsupport-after-execute/2383 .

The only difference is that I don't want to run client-side code to show the message but server-side.

It should behave like when opening the Add-ons manager as an admin. In that case an AUI warning message is shown at the top when the page is loaded.

Thanks in advance!