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Spring #Autowired service is strangely null inspite of using required fields all over [duplicate]

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#Autowired for #ModelAttribute
(2 answers)
Closed 2 years ago.
I am using a pojo for handling form request and I am trying to access service using Autowired. But it keeps returning null inspite of whatever I try changing. I will publish all my code, please take a look into it.
CategoryAddForm:
In this page, I am trying to use categoryService but it seems be empty(null) and when I try using any function inside the service, I get nullpointerexception. I have not tried to initialize the autowired class anywhere.
#Getter
#Setter
#AllArgsConstructor
#NoArgsConstructor
#Component
public class CategoryAddForm {
private Long id;
private String title;
private String description;
private String language;
private String image_url;
#Autowired
CategoryService categoryService;
public Category save() {
Category category;
if(this.id==null) {
if(this.language==null || this.language.trim().equals("en")) {
category = Category.builder()
.title_en(this.title)
.description_en(this.description)
.image_url(this.image_url)
.en_available(true)
.count(0l).build();
System.out.println("New for English: \n id: "+this.id+" \n title:"+this.title+"\n description: "+this.description+"\n language: "+this.language);
System.out.println(categoryService);
// categoryService.save(category);
}
else {
category = Category.builder()
.title_np(this.title)
.description_np(this.description)
.np_available(true)
.en_available(false)
.count(0l).build();
System.out.println("New for Nepali: \n id: "+this.id+" \n title:"+this.title+"\n description: "+this.description+"\n language: "+this.language);
System.out.println(categoryService);
// categoryService.save(category);
}
}
else {
if(this.language==null || this.language.trim().equals("en")) {
category = Category.builder()
.id(this.id)
.title_en(this.title)
.description_en(this.description)
.en_available(true)
.image_url(this.image_url).build();
}
else {
category = Category.builder()
.id(this.id)
.title_np(this.title)
.description_np(this.description)
.np_available(true)
.image_url(this.image_url).build();
}
}
System.out.println(category);
return categoryService.save(category);
}
}
Form page:
This page sends categoryForm object to /save in controller which invokes the save function that is inside CategoryAddForm
<form th:action="#{'/admin/category/save'}" method="post" th:object="${categoryForm}">
<div class="form-group my-1 p-2 row">
<label for="categoryTitle">Title</label>
<input type="title" class="form-control" name="title" id="categoryTitle" th:field="*{title}">
</div>
<div class="form-group my-1 p-2 row">
<label for="categoryDescription">Description</label>
<textarea rows="5" type="description" class="form-control" name="description" id="categoryDescription" th:field="*{description}">
</textarea>
</div>
<div class="form-check my-1 p-2 row">
<label for="languages">Select Language</label>
<div id="languages" class="row ml-2">
<div class="col-2" >
<input class="form-check-input" type="radio" value="en" th:field="*{language}" id="englishLanguage" th:selected="selected">
<label class="form-check-label" for="englishLanguage">
English
</label>
</div>
<div class="col-2" >
<input class="form-check-input" type="radio" value="ne" th:field="*{language}" id="nepaliLanguage">
<label class="form-check-label" for="nepaliLanguage">
Nepali
</label>
</div>
</div>
</div>
<button type="submit" class="btn btn-primary m-2">Submit</button>
</form>
Category Service Implementation:
This is just for the reference and proof that I have not done anything wrong.
#Service
public class CategoryServiceImpl implements CategoryService {
#Autowired
private CategoryRepository repository;
#Override
public Category save(Category document) {
return repository.save(document);
}
#Override
public Category getById(Long id) {
return repository.getOne(id);
}
#Override
public void delete(Category document) {
repository.delete(document);
}
#Override
public void deleteById(Long id) {
repository.deleteById(id);
}
#Override
public List<Category> getAllCategories() {
return repository.findAll();
}
}
save route in CategoryAdminController:
This function is taking categoryAddForm from the form and calls save() function in categoryAddForm.
#PostMapping(value = "/save")
public ModelAndView submitCategory(#ModelAttribute("categoryForm") CategoryAddForm categoryForm, BindingResult result){
categoryForm.save();
if(result.hasErrors()){
return new ModelAndView("redirect:/admin/category/add?error");
}
return new ModelAndView("redirect:/admin/category/add");
}

The problem is that you are creating a new CategoryAddForm every time you make a reuqest and you are not letting spring manage your beans. If you are creating a new instance of CategorAddForm, spring won't know that he needs to inject your service into it. I think you can try to inject by constructor.

I am working on a spring mvc project and I want to submit values from two drop boxes and a text box

I have to take month (drop box), year (drop box) and text from the user, which is packaged as a 'Permissions' class object, and sent to the server.
<div id="Setpermissions" class="modal">
<div class="modal-content animate" >
<div class="imgcontainer">
<span onclick="document.getElementById('Setpermissions').style.display='none'" class="close" title="Close Modal">×</span>
</div>
<form id="my-form" action = "Permissions" method="post">
<select name="mon" multiple="multiple" size="10">
<%
for(i=1;i<13;i++) {
out.println("<option value = " + i + "> " + Month.of(i) + "<option>");
}
%>
</select>
<select name="year" multiple="multiple" size="10">
<%
int year = Integer.parseInt(Year.now().toString());
for(i=1;i<13;i++) {
out.println("<option value = " + year + "> " + year + "<option>");
year=year-1;
}
%>
</select>
<fieldset>
<label><input id="Reason" placeholder="Reason" type="text" name="Reason"></label>
</fieldset>
<!-- use this for server-side processing -->
<input type="submit" name="submitted" value="submit" />
</form>
</div>
</div>
Here is my servlet code:
#RequestMapping(value = "/Permissions", method = RequestMethod.POST)
public String Permissions(#Validated Permissions per, Model model) {
System.out.println(per.getReason());
return "user";
}
}
Permissions class:
public class Permissions {
private int mon;
private int year;
private String reason;
private String permission;
public String getPermission() {
return permission;
}
public String getReason() {
return reason;
}
}
But I am not getting directed to the right page (user.jsp), and the values are not reaching the servlet. Please help

2 Things you should try:
Your backing object (Permissions in this case) should have both Getters and Setters for all fields. This is because, when you click submit and send your request to your backend, Spring will call the setX(x) methods for each field. (ex. setYear(year)). As you have no Setters, I don't believe this will work.
You are using capitalized names in your HTML (Reason) instead of the exact field name (reason). I'm not sure if this affects anything, but might try it.

How to stay on the same page after form submit thymleaf and Spring boot?

Hello guys i have a question regarding what is mentioned in the title. Is it possible to stay on the same page and submit . I found something with javascript but it is not working for me because i m using thymleaf and spring boot. Or i just don't know how to adapt it to my case.
thymeleaf code:
<form th:action="#{/tweets/tweet}" th:object="${tweet}" method="post">
<div class="row">
<div class="col">
<input type="text" th:field="*{content}" class="form-control" placeholder="What's happening? Tell us!">
</div>
<div class="col">
<input class="form-control" type="submit" value="Submit" />
</div>
</div>
</form>
the controller class:
#Controller
#RequestMapping("tweets")
#Slf4j
public class TweetController {
private TweetService tweetService;
public TweetController(TweetService tweetService) {
this.tweetService = tweetService;
}
#PostMapping("/tweet")
#ResponseStatus(CREATED)
public Tweet tweet(#Valid #ModelAttribute("tweet") Tweet tweet, Principal
principal, BindingResult result) {
if(result.hasErrors()){
//do somethign
}
if (!tweet.getContent().equals(null) && !tweet.getContent().equals("") && !tweet.getContent().isEmpty()) {
tweetService.createTweet(tweet.getContent(), principal);
}
}
#GetMapping("/")
public String goToIndex(Model model){
model.addAttribute("tweet",new Tweet());
return "overview";
}
And i have server.context-path=/api
I have one more additional question to this topic. When i wanted to redirect it to another page i was getting a blank page. Not an error not an exception just a blank page. Any help ? I m new to this.

Yes, this is possible using ajax. I would recommend doing it using jQuery though. So, if you would like to submit your form and stay in the same page, you could do the following.
HTML
<form id="tweet-form" th:action="#{/tweets/tweet}" th:object="${tweet}" method="post">
<div class="row">
<div class="col">
<input type="text" th:field="*{content}" class="form-control" placeholder="What's happening? Tell us!">
</div>
<div class="col">
<input id="submit-form" class="form-control" type="button" value="Submit" />
</div>
</div>
</form>
Changes:
Added an id to the form.
Added an id to your input.
Change submit input's type for button.
jQuery
$('#submit-form').on('click', function() {
var form = $('#tweet-form');
$.ajax({
url: form.attr('action'),
data: form.serialize(),
type: post,
success: function(result) {
// Do something with the response.
// Might want to check for errors here.
}, error: function(error) {
// Here you can handle exceptions thrown by the server or your controller.
}
})
}
Controller
#PostMapping("/tweet")
#ResponseStatus(CREATED)
public Tweet tweet(#Valid #ModelAttribute("tweet") Tweet tweet, Principal
principal, BindingResult result) {
if(result.hasErrors()){
// Throw an exception or send a null Tweet.
}
if (!tweet.getContent().equals(null) && !tweet.getContent().equals("") && !tweet.getContent().isEmpty()) {
tweetService.createTweet(tweet.getContent(), principal);
}
// You are returning a Tweet, so you must return something.
return tweet;
}
Your controller pretty much stay the same. Just remember to return something.

Your example doesn't show what the tweet() method returns. It should return a Tweet object but doesn't have any return value. What are you attempting to do with that return value? If you're not handling it with Javascript someway, then get rid of #ResponseStatus(CREATED) and return a either a Model or a String pointing to your html file, like so:
#PostMapping("/tweet")
public String tweet(#Valid #ModelAttribute("tweet") Tweet tweet, Principal
principal, BindingResult result) {
if(result.hasErrors()){
//do somethign
}
if (!tweet.getContent().equals(null) && !tweet.getContent().equals("") && !tweet.getContent().isEmpty()) {
tweetService.createTweet(tweet.getContent(), principal);
}
return "redirect:/name-of-html-file";
}
reference
If you want thymeleaf to handle the tweet and the HttpStatus you could instead return something along the lines of
ModelAndView model = new ModelAndView("your-view");
model.addAttribute(tweet);
model.setStatus(HttpStatus.CREATED);
return model;

Neither BindingResult nor plain target object for bean name 'matrix[0][0]' available as request attribute

I have a matrix (array of arrays) of boolean values which I want to show in a form and then submit after changing. I have problems rendering this and I have no more ideas why it is not working. Can anybody give me an advice?
My Controller:
#Controller
#RequestMapping(value = "/konfiguration")
public class VerteilungController {
#ModelAttribute("matrix")
public List<List<Boolean>> getVerteilungenMatrix() {
List<List<Boolean>> result2 = new ArrayList<>();
for (int i = 0; i < kategorien.size(); i++) {
result2.add(new ArrayList<>());
}
//...
return result2;
}
#RequestMapping(value = "/verteilung", method = RequestMethod.GET)
public String showPage(Model model) {
model.addAttribute("matrix", getVerteilungenMatrix());
return "konfiguration/verteilung";
}
}
The form:
<form id="verteilung_form" class="form-horizontal" method="post" action="/verteilung"
th:action="#{/konfiguration/verteilung}"
th:object="${matrix}">
<table class="table-hover">
<tr th:each="row: ${matrix}">
<td th:each="value: ${row}">
<input type="checkbox" th:field="${matrix[__${rowStat.index}__][__${valueStat.index}__]}"/>
</td>
</tr>
</table>
<div >
<button th:text="#{button.save}" class="btn btn-default" type="submit" name="save">Speichern</button>
<button th:text="#{button.reset}" name="reset" class="btn btn-default">Zurücksetzen</button>
</div>
</form>
Openening the page I get
Exception: Error during execution of processor 'org.thymeleaf.spring4.processor.attr.SpringInputCheckboxFieldAttrProcessor'
And in the log
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'matrix[0][0]' available as request attribute

You've misused th:object and th:field. th:object stands for command objects which represents the entire form.
Command object is the name Spring MVC gives to form-backing beans, this is, to objects that model a form’s fields and provide getter and setter methods that will be used by the framework for establishing and obtaining the values input by the user at the browser side.
On the other hand th:field does all the heavy work of binding your input with a property in the form-backing bean. Values inside th:field should point to a field of the object from th:object.
Values for th:field attributes must be selection expressions (*{...}), which makes sense given the fact that they will be evaluated on the form-backing bean and not on the context variables (or model attributes in Spring MVC jargon).
Please check it out here.
So back to your code. To fix it you should create a form-backing bean class and provide the matrix as a field inside that class, for example:
public class FormBean {
private List<List<Boolean>> matrix;
FormBean() { }
public FormBean(List<List<Boolean>> matrix) {
this.matrix = matrix;
}
public List<List<Boolean>> getMatrix() {
return matrix;
}
public void setMatrix(List<List<Boolean>> matrix) {
this.matrix = matrix;
}
}
Next please provide object of FormBean as a model attribute. When you provide method marked as #ModelAttribute then assignment to a model will be done for you. Update your controller body to the following:
#ModelAttribute("formBean")
public FormBean getFormBean() {
return new FormBean(getVerteilungenMatrix());
}
#RequestMapping(value = "/verteilung", method = RequestMethod.GET)
public String showPage() {
return "konfiguration/verteilung";
}
private List<List<Boolean>> getVerteilungenMatrix() {
List<List<Boolean>> result2 = new ArrayList<>();
for (int i = 0; i < kategorien.size(); i++) {
result2.add(new ArrayList<>());
}
//...
return result2;
}
Finally please update your form to the following:
<form id="verteilung_form" class="form-horizontal" method="post" action="/verteilung"
th:action="#{/konfiguration/verteilung}"
th:object="${formBean}">
<table class="table-hover">
<tr th:each="row: *{matrix}">
<td th:each="value: ${row}">
<input type="checkbox" th:field="*{matrix[__${rowStat.index}__][__${valueStat.index}__]}"/>
</td>
</tr>
</table>
<div >
<button th:text="#{button.save}" class="btn btn-default" type="submit" name="save">Speichern</button>
<button th:text="#{button.reset}" name="reset" class="btn btn-default">Zurücksetzen</button>
</div>
</form>
Now everything should work as expected.

How to validate date format in spring form without using Annotation?

addEmployee.jsp
<form:form id="bookForm" modelAttribute="employee" method="post" action="${baseURL}employee/saveemployee" class="form-horizontal" enctype="multipart/form-data">
<div class="form-group">
<label for="publishedOn" class="col-xs-4 control-label">Birth Date
</label>
<div class="col-xs-8">
<form:input path="personalInformation.dateOfBirth" placeholder="yyyy-MM-dd" class="datepicker form-control" />
<form:errors path="personalInformation.dateOfBirth"></form:errors>
</div>
</div>
<div class="form-group">
<label for="dateOfJoining" class="col-xs-4 control-label">Date Of Joining</label>
<div class="col-xs-8">
<form:input path="dateOfJoining" placeholder="dateOfJoining" class="form-control" />
<form:errors path="dateOfJoining"></form:errors>
</div>
</div>
</form:form>
This is jsp form in which i have to validate date feilds
whenever i click on save button it gives null pointer exception.
2)EmployeeAddController.java
#RequestMapping(value="/saveemployee",method = RequestMethod.POST)
public String saveEmployee(#ModelAttribute("employee")Employee employee,BindingResult result,Errors e,ModelMap map){
employeeValidatorobj.validate(employee,e);
if(e.hasErrors())
{
map.addAttribute("employee",employee);
return "addEmployee";
}
else{
System.out.println("inside save");
System.out.println(employee.getPersonalInformation().getFirstName());
map.addAttribute("employee",new Employee());
iEmployeeService.saveEmployee(employee);
map.addAttribute("message", "EmployeeAdded sucessfully");
return "employeeList";
}
}
This is controller here i am checking if form has errors or not.`
3)emolyeeValidator.java
public class EmployeeValidator implements Validator {
private Pattern pattern;
private Matcher matcher;
private static final String DATE_PATTERN="((?:19|20)\\d\\d)/(0?[1-9]|1[012])/([12][0-9]|3[01]|0?[1-9])";
#Override
public boolean supports(Class<?> arg0) {
return Employee.class.equals(arg0);
}
#Override
public void validate(Object obj, Errors errors) {
// Employee employee=new Employee();
Employee employee = (Employee) obj;
String date=employee.getDateOfJoining().toString();
if (!date.matches(DATE_PATTERN)) {
pattern=pattern.compile(DATE_PATTERN);
matcher=pattern.matcher(date);
if(matcher.matches()){
errors.rejectValue("dateOfJoining", "dateOfJoining.incorrect","enter correct dateOfJoining");
}
}
This is employeeValidator class for custome validation of date but when i am try to save record it gives null pointer exception.i have also mapped employeevalidator in bean.and whenever iam trying to validate with .equals() string method then it gives exception on jsp page string cannot convert into java.util.Date.please check code and suggest me how to check condition in employeeValidator for date format (YYYY-MM-DD)