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How to retrieve a list of data in spring boot without passing any variable. We are passing only URL for the GET request.

For example, in below code I am passing "roll no" and it is working fine, it is fetching corresponding student detail.

 @GetMapping{"/fetch/{rollNo}")
   
   public List<StudentDetail> findStudentDeatilbyRollNo (@PathVariable String rollNo){
    return StudentService.findStudentDetailByRollNo(rollNo);
  }

But when I want to fetch all student data without passing parameter it is giving me error "Non-static method 'fetchAllStudentDetail()' can not be referenced from a static context"

@GetMapping{"/allStudentDetails")
   
   public List<StudentDetail> fetchAllStudentDeatil(){
    return StudentService.fetchAllStudentDeatil();
  }

Someone, please help me with the problem.

Rajeev
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3 Answers3

1

The error means that you are trying to call a non static method in a static way :

To fix that, try to make this method static.

StudentService.fetchAllStudentDeatil()

To make it static you add the static word

public static List<StudentDetail> fetchAllStudentDeatil()
DEV
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1

I see several issues in your code, follow below steps to resolve.

  1. In your RestController class autowire StudentService.

Example 1:

@Autowired  
private StudentService studentService;

Example 2:

private final StudentService studentService;

@Autowired
public RestControllerClassName(StudentService studentService){
    this.studentService = studentService;
}

Read more: Spring @Autowire on Properties vs Constructor

  1. Add @Service in the StudentService class.

  2. Remove static from both the methods in StudentService fetchAllStudentDeatil() and findStudentDetailByRollNo(rollNo).

  3. Finally in your RestController, use studentService.fetchAllStudentDeatil() and studentService.fetchAllStudentDeatil(rollNo)

  4. Optional, correct the typo in Deatil

Gaurav kumar Singh
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you need to define the function fetchAllStudentDeatil inside student service where you are retrieving all the entries in your table ;

static List<Student> fetchAllStudentDeatil {     return studentRepo.findAll();  }

Also make sure that the method on GetMapping is not static . In case it is, make the fetchAllStudentDeatil also static.

Gurkirat Singh Guliani
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  • I already have defined fetchAllStudentDeatil inside student service. How to make fetchAllStudentDeatil static. – Rajeev Dec 30 '21 at 09:11
  • by adding the keyword static in the method definition. I have updated my answer . let me know if it helps or some other error persist – Gurkirat Singh Guliani Dec 30 '21 at 09:12
  • Singh Thank you, But in Controller class "fetchAllStudentDeatil" is non-static . I don't want to make service ,repo or entity class methods static because there are many other methods depending on those classes. Is there any other way? – Rajeev Dec 30 '21 at 09:19
  • please share your controller class, student service and the repo. it will be easier to assist. Having said that, the error you quoted usually comes when we try to access non static method from a static block of code. – Gurkirat Singh Guliani Dec 30 '21 at 09:21