Themeleaf issue with can not be null variable - spring

Question

I was trying to send the posts to DB. However,when I tried to use themeleaf, it shows me the following error:
EL1007E: Property or field 'name' cannot be found on null Exception evaluating SpringEL expression: "name" (template: "StudentForm" - line 264, col 49) An error happened during template parsing (template: "class path resource [templates/StudentForm.html]")
This is what I tried below:
StudentForm.html
<div class="col-lg-10">
<div class="card">
<div class="card-header">
<strong>Basic Form</strong> Elements
</div>
<div class="card-body card-block">
<form th:action="#{/StudentForm}" th:Object="${student}" method="post" enctype="multipart/form-data" class="form-horizontal" role="form">
<div class="row form-group">
<div class="col col-md-3">
<label for="text-input" th:field="*{name}" class=" form-control-label">Ismi sharifi</label>
</div>
<div class="col-12 col-md-9">
<input type="text" id="text-input" placeholder="Iltimos ismni kiriting" class="form-control">
</div>
</div>
<div class="row form-group">
<div class="col col-md-3">
<label for="select" class=" form-control-label">Fakulteti</label>
</div>
<!-- <div class="col-12 col-md-9">
<select name="select" id="select" class="form-control">
<option value="0">Fakultetni tanlang</option>
<option value="1">Option #1</option>
<option value="2">Option #2</option>
<option value="3">Option #3</option>
</select>
</div>
</div> -->
<div class="row form-group">
<div class="col col-md-3">
<label for="email-input" class=" form-control-label">Email Input</label>
</div>
<div class="col-12 col-md-9">
<input type="email" id="email-input" th:field="*{email}" placeholder="Emailni kiriting" class="form-control">
<small class="help-block form-text"></small>
</div>
</div>
<div class="row form-group">
<div class="col col-md-3">
<label for="text-input" class=" form-control-label">To'langan summa</label>
</div>
<div class="col-12 col-md-9">
<input type="text" id="text-input" placeholder="Summani kiriting" class="form-control">
</div>
</div>
<div class="row form-group">
<div class="col col-md-3">
<label for="file-input" class=" form-control-label">File input</label>
</div>
<div class="col-12 col-md-9">
<input type="file" id="file-input" name="file-input" class="form-control-file">
</div>
</div>
</form>
</div>
<div class="card-footer">
<button type="submit" class="btn btn-primary btn-sm">
<i class="fa fa-dot-circle-o"></i> Yuklash
</button>
<button type="reset" class="btn btn-danger btn-sm">
<i class="fa fa-ban"></i> Reset
</button>
</div>
</div>
StudentController.java
package io.javabrains;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.validation.Valid;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
import io.javabrains.Entities.Student;
import io.javabrains.repository.StudentRepository;
import io.javabrains.service.StudentService;
#Controller
public class StudentController {
#Autowired
private StudentRepository repository;
#Autowired
private StudentService service;
#RequestMapping(value= {"/student"},method=RequestMethod.GET)
public ModelAndView student(HttpServletRequest request) {
request.setAttribute("Student", service.findAll());
request.setAttribute("mode", "MODE_TASKS");
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName("student");
return modelAndView;
}
#RequestMapping(value="/StudentForm",method=RequestMethod.POST)
public ModelAndView studentForm(#Valid Student student,BindingResult bindingResult,ModelMap modelMap)
{
ModelAndView modelAndView = new ModelAndView();
service.addStudent(student);
modelAndView.addObject("student",new Student());
modelAndView.setViewName("studentForm");
return modelAndView;
}
#RequestMapping(value={"/StudentForm"},method=RequestMethod.GET)
public ModelAndView studentForm() {
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName("StudentForm");
return modelAndView;
}
public List<Student>getAllEmployers(){
return service.findAll();
}
StudentEntity.java
package io.javabrains.Entities;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.validation.constraints.NotNull;
#Entity
#Table(name = "student")
public class Student {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "studentId")
private int studentId;
#Column(name="name")
#NotNull(message = "Name is compulsort")
private String Name;
#Column(name="email")
#NotNull(message = "Email is compulsory")
private String Email;
#Column(name="department")
#NotNull(message = "department is compulsort")
private String Department;
#Column(name="amount")
#NotNull(message = "Amount is compulsort")
private double Amount;
#ManyToOne
#JoinColumn(name="studentId",referencedColumnName="id",insertable=false, updatable=false)
private DepartmentCategory departmentCategory;

Answer 1

First of all your controller should contain get method which returns Student object as a form to bind. You missed that. It should look something like this:
#RequestMapping(value={"/StudentForm"},method=RequestMethod.GET)
public ModelAndView studentForm() {
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("student", new Student()) //returns object to thymeleaf context
modelAndView.setViewName("StudentForm");
return modelAndView;
}
then you should change your naming convention in your student class, fields should start with lower case. You should notice that you have field Name in your Student class but you want to map th:field="*{name}" in thymeleaf view.
Read something about DTO and Models because you shouldn't use your entities directly in controller layer