Chapter I & II
- How to write a controller
- How to write a template
- How to add attributes to Model object
- How to perform validation
- How to write a “controller” which does simple things
How to write a controller
@Controller
@RequestMapping("/path")
public class MyCOntroller {
@GetRequest
public String getMapping(Model model) {
model.addAttribute("...", ...); //How to add attributes to Model object
...
return "templateName";
}
@PostRequest
public String getMapping(@Valid @ModelAttribute('attrName') MyClass onject, Errors errors) {
if (errors.hasErrors()) { // Perform validation
//do something for the error
}
//do something (business logic)
return "templateName";
}
}
How to write a template
Example.
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml"
xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Post Course</title>
</head>
<body>
<form method="post" th:object="${course}">
<h3>Enter course name: </h3>
<input type="text" th:field="*{name}"/>
<!--perform validation-->
<span th:if="${#fields.hasErrors('name')}"
th:errors="*{name}">Name Error</span>
<h3>Enter lecture sections</h3>
<textarea th:field="*{lecs}"></textarea>
<h3>Enter tutorial sections</h3>
<textarea th:field="*{tuts}"></textarea>
<h3>Enter lab sections</h3>
<textarea th:field="*{labs}"></textarea>
<button>Submit your course</button>
</form>
</body>
</html>
Key points
<html lang="en" xmlns="http://www.w3.org/1999/xhtml"
xmlns:th="http://www.thymeleaf.org">
How to perform validation
Combine with the previous code, in model class add annotations:
@Data //@Data is lombok annotation which auto generates constructor, getters, and setters for the fields.
public class MyClass {
@Size(min=3, message="error message") // there are other constrains, such as @Pattern...
private String someInfo;
...
}
How to write a “controller” which does simple things.
@Configuration
public class WebConfig implements WebMvcConfigurer {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/path").setViewName("viewName");
}
}
Other
@Slf4j: is in lombok which provides a logger. (Simply log.info("info");)