I am new to spring and am trying to pass a string value via radio button in a form to a controller, then to a view. I can do it with no problem if the controller @RequestParam type is string. But what I want to do next is map the radio button attrib value to an object such as:
@Component
public class ChoiceBean {
private String choice;
public String getChoice() {
return choice;
}
public void setChoice(String choice) {
this.choice = choice;
}
@Override
public String toString() {
return "ChoiceBean{" + "choice=" + choice + '}';
}
}
...but it returns null in the view. What am I doing wrong?
I used this to update my controller methods getChoice() & processChoiceGet().
Here are my files:
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany</groupId>
<artifactId>flashcards-springboot</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>flashcards-springboot</name>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.4.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<properties>
<java.version>1.8</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
form in html
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<title>TODO supply a title</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<div>
<form action="processChoice" method="post">
<input type="radio" name="choicebean" value="1" checked=true>1<br>
<input type="radio" name="choicebean" value="2">2<br>
<input type="submit" value="Submit"/>
</form>
</div>
</body>
</html>
Controller
@Controller
public class FileUploadController {
private static final Logger slf4jLogger
= LoggerFactory.getLogger(FileUploadController.class);
// Holds keys, values in order
Map<String, String> map = new LinkedHashMap<>();
@Autowired
private Utils utils;
@Autowired
ChoiceBean choiceBean;
@GetMapping("/")
public String home() throws IOException {
return "home";
}
// Called from home view
@PostMapping("/upload")
public String handleFileUpload(
@RequestParam("file") MultipartFile file, Model model) {
// Clear map in case of new file upload
map.clear();
try {
// Add map to model
model.addAttribute("theMap",
utils.mapInputStringToMap(file.getBytes()));
} catch (IOException ex) {
slf4jLogger.error(FileUploadController.class.getName(), ex.getCause());
}
return "choice-1";
}
// Map object to attribute
@ModelAttribute("choice")
public ChoiceBean getChoice(HttpServletRequest request)
{
return (ChoiceBean) request.getAttribute("choicebean");
}
@PostMapping("/processChoice")
public String processChoiceGet(
@ModelAttribute("choice") ChoiceBean choice, Model model) {
// Log
slf4jLogger.info("result: " + choice.getChoice());
model.addAttribute("choice",choice.getChoice());
return "flash-card";
}
Output view
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<title>Getting Started: Serving Web Content</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<p th:text="'Hello, ' + ${choice} + '!'" />
</body>
</html>
EDIT: I added an array of numbers to be used as radio button display in handleFileUpload() [<-this works]; also removed getString() from choice:
@Controller
public class FileUploadController {
private static final Logger slf4jLogger
= LoggerFactory.getLogger(FileUploadController.class);
// Holds keys, values in order
Map<String, String> map = new LinkedHashMap<>();
@Autowired
private Utils utils;
@Autowired
ChoiceBean choiceBean;
@GetMapping("/")
public String home() throws IOException {
return "home";
}
// Called from home view
@PostMapping("/upload")
public String handleFileUpload(
@RequestParam("file") MultipartFile file, Model model) {
// Clear map in case of new file upload
map.clear();
try {
// Add map to model
model.addAttribute("theMap",
utils.mapInputStringToMap(file.getBytes()));
model.addAttribute("sources", new String[]{"1", "2"});
} catch (IOException ex) {
slf4jLogger.error(FileUploadController.class.getName(), ex.getCause());
}
return "choice-1";
}
@ModelAttribute("choice")
public ChoiceBean getChoice(HttpServletRequest request)
{
return (ChoiceBean) request.getAttribute("choicebean");
}
@PostMapping("/processChoice")
public String processChoiceGet(
@ModelAttribute("choice") ChoiceBean choice, Model model) {
// Log
slf4jLogger.info("result: " + choice);
model.addAttribute("choice",choice);
return "flash-card";
}
}
...and edited the form to try to capture the command object as 'choice', but value is still null in the view. How can I get the chosen radio button value as a string to display in the view?
<form th:object="${choice}" th:action="@{/processChoice}" method="post">
<div th:each="source : ${sources}">
<input name="source" type="radio" th:value="${source}"/>
<label th:for="source" th:text="${source}">my label</label>
</div>
<input type="submit" value="Submit"/>
</form>
