Spring-Boot MVC JPA Filters

Let me start by saying I’m fairly new to Spring Boot so apologies if I’m making a silly mistake somewhere. I am trying to retrieve the value of my form post using @RequestParam so I can utilize it in a JPA query to return kids who have a specific pet type. I’ve done other JPA queries and had successful results, but getting the Enum value from a populated select so I can pass it back to the controller query has me stumped.

I keep getting the error:

Required request parameter ‘p’ for method parameter type String is not present

I need to pass the petType to the Post method findByPet_PetTypeEquals in order to retrieve what kids have that particular pet type. I just can’t figure out how to pass that form data back to the controller.

Kid class:

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id; 
    
    private String name;
    
    private Integer age;
    
    @OneToOne
    @JoinTable(name="KID_PET", joinColumns=@JoinColumn(name="KID_ID"),
    inverseJoinColumns=@JoinColumn(name="PET_ID"))
    private Pet pet;

Pet class:

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;
    private String name;
    private Boolean furry; 
    
    @Enumerated(EnumType.STRING)
    private PetType petType;

PetType Enum:

public enum PetType {
    
    DOG, CAT, FISH, BIRD, HAMSTER;

}

Relevant Controller Methods:

    private KidRepository kidRepo;
    
    @GetMapping("/")
    public String index(Model model) {
        
        model.addAttribute("kid", new Kid());
        model.addAttribute("petType", PetType.values());
        
        return "index";
    }

    @PostMapping("/findByPet_PetTypeEquals")
    public String findByPet_PetTypeEquals(Model model, @RequestParam String p) {
            
        
        List<Kid> kidList = kidRepo.findByPet_PetTypeEquals(p);
        model.addAttribute("kidList", kidList);
        
        return "displayKid";
        
    }

Form:

    <form method="post" th:action="findByPet_PetTypeEquals">
    
        Pet Type: <select th:field="*{petType}">
        
        <option th:each="p : ${petType}" th:value="${p}" th:text="${p}"></option>
        
        </select>
    
        <button type="submit">Submit</button>
        
    </form>

Repo:

public interface KidRepository extends JpaRepository<Kid, Long>{
    
    public List<Kid> findByAgeGreaterThan(Integer age); // DONE
    public List<Kid> findByPetNotNull(); // DONE
    public List<Kid> findByPet_PetTypeEquals(String p); // NOT DONE
    public List<Kid> findByPet_FurryIsTrue(); // DONE
}

Any advice or guidance is greatly appreciated! Thank you.

Answer

as method param in findByPet_PetTypeEquals, give Enum instead of String.

@Enumerated is just an annotation that allows JPA/hibernate to store enum as string in DB and while retrieving convert string to enum. So, in your method param, it should be enum type