Combine Thymeleaf error pages

[php-coder]

We have 3 error pages (src/main/webapp/WEB-INF/views/error/{403,404,500}.html) that nearly identical to each other:

--- 403.html    2019-05-07 18:43:19.988009600 +0100
+++ 500.html    2019-05-07 18:43:19.993828400 +0100
@@ -10,3 +10,3 @@
                <meta name="robots" content="noindex" />
-               <title th:text="#{t_403_title}">403: forbidden</title>
+               <title th:text="#{t_500_title}">500: internal server error</title>
                <link rel="shortcut icon" type="image/x-icon" href="../../../favicon.ico" th:href="${FAVICON_ICO}" />
@@ -56,6 +56,6 @@
                                        <h1 id="error-code">
-                                               403
+                                               500
                                        </h1>
-                                       <h4 id="error-msg" th:text="#{t_403_description}">
-                                               Forbidden
+                                       <h4 id="error-msg" th:utext="#{t_500_description('&lt;br /&gt;')}">
+                                               Internal<br />server error
                                        </h4>

The difference are the following:

• title
• error code
• error message

The task is to combine them into a single page and use condition to find out what eror message/code. Perhaps, we can utilize th:switch/th:case.

See also https://www.thymeleaf.org/doc/articles/springsecurity.html part 3 with an example of that approach. Keep in mind, that our approach will be similar by idea but not literally -- we won't pass error message from controller but will decided what message to show dependig on a reponse status.

[mukeshk]

Currently ErrorPagesCustomizer - maps to different request - to respective methods in ErrorController.
As per Step#3 of the Article shared. we need to have common exception handler.
Do we need to make changes to ErrorController?

[php-coder]

Thank you, Mukesh! It's indeed a good question!

Currently ErrorPagesCustomizer - maps to different request - to respective methods in ErrorController.

Yes, ErrorPagesCustomizer maps errors to URLs and these URLs are served by ErrorController (all expect FORBIDDEN_PAGE).

As per Step#3 of the Article shared. we need to have common exception handler.

As far I see we don't need a common exception handler, we might have many exception handling mechanisms but all of them should use a single view.

Do we need to make changes to ErrorController?

Yes, we need to modify both methods to return a String type (instead of void) and return name of a view file (let's name it "error/status-code").

In order to modify FORBIDDEN_PAGE, we need to change

mystamps/src/main/java/ru/mystamps/web/config/MvcConfig.java

Line 108 in 41b4250

registry.addViewController(SiteUrl.FORBIDDEN_PAGE);