inject model data into spring webflow in cas - cas

Question

I am upgrading a CAS 4 to a CAS 6. I have done several Spring Boot 2 apps, so I know what I am doing there. I can even do some webflow, but only from scratch.
The documentation clearly states not to mess with the base webflow xml, and to "inject" your own services.
How does one "inject" a service? I really just need to add a message of the day to the login page.
Does anyone have an example of something this simple?

Answer 1

Find below my approach, tested on a cas-maven-overlay installation with cas version at 5.3.x. Some things maybe different on cas 6 branch but I assume the main idea remains.
First, we should create an Action class that will be injected in the login flow and will add the desired message in the flow scope in order to be available at the template(view).
public class DailyMessageAction extends AbstractAction{
#Override
protected Event doExecute(RequestContext context) throws Exception {
context.getFlowScope().asMap().put("dailyMessage", "YOUR_AWESOME_MESSAGE");
return success();
}
}
Then create a WebflowConfigurer class and inject our newly created DailyMessageAction in the actions list(see doInitialize method).
public class DailyMessageWebflowConfigurer extends AbstractCasWebflowConfigurer{
final Action dailyMessageAction;
public DailyMessageWebflowConfigurer(FlowBuilderServices flowBuilderServices,
FlowDefinitionRegistry flowDefinitionRegistry,
ApplicationContext applicationContext,
CasConfigurationProperties casProperties,Action dailyMessageAction){
super(flowBuilderServices, flowDefinitionRegistry, applicationContext, casProperties);
this.dailyMessageAction = dailyMessageAction;
}
#Override
protected void doInitialize() {
final Flow flow = super.getLoginFlow();
flow.getStartActionList().add(dailyMessageAction);
}
}
After that we should inject DailyMessageWebflowConfigurer in cas runtime. This is achieved by creating a configuration class and inject our configurer.
#Configuration
public class CustomWebflowConfiguration {
#Autowired
private CasConfigurationProperties casProperties;
#Autowired
#Qualifier("loginFlowRegistry")
private FlowDefinitionRegistry loginFlowDefinitionRegistry;
#Autowired
private ApplicationContext applicationContext;
#Autowired
private FlowBuilderServices flowBuilderServices;
#RefreshScope
#ConditionalOnMissingBean(name = "dailyMessageAction")
#Bean
public Action dailyMessageAction(){
return new DailyMessageAction();
}
#ConditionalOnMissingBean(name = "dailyMessageWebflowConfigurer")
#Bean
#RefreshScope
public CasWebflowConfigurer dailyMessageWebflowConfigurer(){
final DailyMessageWebflowConfigurer w = new DailyMessageWebflowConfigurer(flowBuilderServices,
loginFlowDefinitionRegistry,
applicationContext,
casProperties,
dailyMessageAction());
w.initialize();
return w;
}
}
Include our CustomWebflowConfigurationclass in META-INF/spring.factories:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=your_package.CustomWebflowConfiguration
The final step is to present the added message in the view. Achieved by adding this line
<div th:utext="${dailyMessage}"></div>
in the templates/casLoginView.html file.

Answer 2

... add a message of the day to the login page...
Modifying the spring webflow directly is not recommended in CAS. read this for more info
So if I were you instead of tinkering with spring webflow, I would try to do something like the following:
Note:
Bare in mind this might not be the recommended way to do so, but I think this will work, and much less work than overriding spring webflow
As you said you are quite familiar with Spring boot, so I won't bored you with detail implementation, I can follow up if you / other reader are confused
If your message of the day can be hard coded, just skip 1-3 and go straight with 4.
Ok here we go:
Override the CasSupportActionsConfiguration, only adding the initialFlowSetupAction bean
Adding a custom class (let named it MyInitialFlowSetupAction) and implement the InitialFlowSetupAction
In MyInitialFlowSetupAction, add something like this:
#Override
public Event doExecute(final RequestContext context) {
Event returnEvent = super.doExecute(context);
configureMyAwesomeMessageOfTheDay(context)
return returnEvent;
}
private void configureMyAwesomeMessageOfTheDay(final RequestContext context) {
String messageOfTheDay = "Spring is the best season!";//Your logic here
context.getFlowScope().put("MESSAGE_OF_THE_DAY", messageOfTheDay);
}
4 . CAS 6 is using WAR overlay, so you can overlay the html file, including this one
https://github.com/apereo/cas/blob/v6.0.3/webapp/resources/templates/casLoginView.html
overlay that file, and add your MESSAGE_OF_THE_DAY to it
<!DOCTYPE html>
<html xmlns:layout="http://www.ultraq.net.nz/thymeleaf/layout" layout:decorate="~{layout}">
...
<body class="login">
<main role="main" class="container mt-3 mb-3">
Message of the day is: ${MESSAGE_OF_THE_DAY}
...
</main>
</body>
</html>
See if this helps you