Doctor Search & Dynamic Filtering with Spring Data JPA

Business Scenario

In this lab, we will enhance the Medicare backend by implementing doctor search and dynamic filtering based on specialization, doctor name, and maximum consultation fee.

Pre-Lab Preparation

Phase 6 — Doctor Search & Dynamic Filtering

Understand Request Parameters

Until now we used things like:

Module:

1) Additional Components in Project

GET /api/doctors/5

Here: 5 identifies one particular doctor.

GET /api/doctors?specialization=Cardiologist

That's a: @PathVariable

Filtering is different.

For example:

Here: specialization=Cardiologist doesn't identify one resource.

It modifies/filter the collection.

Therefore we'll use: @RequestParam

Think of it like:

@PathVariable → Which resource? @RequestParam → How should I filter/search?

First Understand Derived Queries

Spring Data allows us to create methods such as:

List<DoctorProfile> findBySpecializationIgnoreCase( String specialization );

Spring interprets the method name:

find
By
Specialization
IgnoreCase

and automatically generates the database query.

Similarly:

List<DoctorProfile> findByConsultationFeeLessThanEqual(BigDecimal maxFee);

means :

WHERE consultation_fee <= maxFee

Searching Doctor Name Is Interesting

Remember our structure:

DoctorProfile --> User --> name

DoctorProfile itself does not contain: name because name belongs to: User

So Spring Data can navigate the relationship:

List<DoctorProfile> findByUser_NameContainingIgnoreCase(String name);

Read that as:

DoctorProfile -> User -> Name -> Containing -> IgnoreCase

For example Search: anaya can match

Dr. Ananya Sharma

And:

ANANYA
ananya
AnAnYa

all work because of: IgnoreCase

But there is a problem...

Suppose we create methods for every possible combination:

specialization
name
maxFee
specialization + name

specialization + maxFee
name + maxFee
specialization + name + maxFee

We'd eventually end up with ridiculous method names such as:

findBySpecializationIgnoreCaseAndConsultationFeeLessThanEqualAndUser_NameContainingIgnoreCase(...)

Technically possible, but not clean

Add a Doctor Response DTO

This is where we will introduce another DTO.

Why? : Currently returning DoctorProfile gives something like:

{
    "id": 1,
    "user": {
        "id": 2,
        "name": "Dr. Ananya Sharma",
        "email": "ananya@example.com",
        "phone": "9876543211",
        "role": "DOCTOR"
    },
    "specialization": "Cardiologist",
    "experienceYears": 8,
    "consultationFee": 1200
}

The patient doctor listing doesn't need:

email
phone
role

It needs:

Doctor ID
Doctor Name
Specialization
Experience
Fee
Photo

So this is a genuine reason for a DTO

Create DoctorResponse

dto/
└── DoctorResponse.java

package com.medicare.dto;
import java.math.BigDecimal;

public class DoctorResponse {

    private Long id;
    private String name;
    private String specialization;
    private Integer experienceYears;
    private BigDecimal consultationFee;
    private String photoUrl;

Create:

    public DoctorResponse(
            Long id,
            String name,
            String specialization,
            Integer experienceYears,
            BigDecimal consultationFee,
            String photoUrl) {

        this.id = id;
        this.name = name;
        this.specialization = specialization;
        this.experienceYears = experienceYears;
        this.consultationFee = consultationFee;
        this.photoUrl = photoUrl;
    }

    public Long getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getSpecialization() {
        return specialization;
    }

    public Integer getExperienceYears() {
        return experienceYears;

    }

    public BigDecimal getConsultationFee() {
        return consultationFee;
    }

    public String getPhotoUrl() {
        return photoUrl;
    }
}

Update DoctorProfileRepository

Instead of allowing users to type any random value such as:

repository/
└── DoctorProfileRepository.java

Create:

Our final repository can be:

package com.medicare.repository;
import java.math.BigDecimal;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import com.medicare.entity.DoctorProfile;

public interface DoctorProfileRepository
        extends JpaRepository<DoctorProfile, Long> {

    boolean existsByUserId(Long userId);

    @Query(""" 
            SELECT d FROM DoctorProfile d JOIN d.user u WHERE
                (:specialization IS NULL 
                   OR LOWER(d.specialization) = LOWER(:specialization))
            AND
                (:maxFee IS NULL OR d.consultationFee <= :maxFee)
            AND
                (:name IS NULL 
                  OR LOWER(u.name) LIKE CONCAT(CONCAT('%', LOWER(:name)), '%'))
            """)
    List<DoctorProfile> searchDoctors(

            @Param("specialization")
            String specialization,

            @Param("maxFee")
            BigDecimal maxFee,

            @Param("name")
            String name
    );
}

Understand JPQL

We wrote : SELECT d FROM DoctorProfile d

Notice: DoctorProfile and not: doctor_profiles

Why? - Because this is: JPQL not raw SQL.

Why JOIN d.user u?

Our doctor name exists inside:

DoctorProfile -> User -> Name

So: JOIN d.user u gives the query access to u.name

Then we can search: LOWER(u.name)

Optional Specialization

This portion:

(:specialization IS NULL
    OR LOWER(d.specialization) = LOWER(:specialization))

means

Did user provide specialization?
       │
   ┌───┴───┐
   NO      YES
   │        │
 ignore   match specialization
 filter

Maximum Fee

This portion:

(:maxFee IS NULL OR d.consultationFee <= :maxFee)

means if: maxFee = 1000 return doctors charging:

but not:

₹1200
₹1500
₹2000

Doctor Name Search

This portion means: contains

LOWER(u.name)
LIKE CONCAT(CONCAT('%', LOWER(:name)), '%')

So searching: ananya can find: Dr. Ananya Sharma

Searching: sharma can also find: Dr. Ananya Sharma

Update DoctorService

We're also going to start returning DoctorResponse instead of exposing the complete DoctorProfile entity through our public doctor APIs.

package com.medicare.service;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;
import org.springframework.stereotype.Service;
import com.medicare.dto.DoctorProfileRequest;
import com.medicare.dto.DoctorResponse;
import com.medicare.entity.DoctorProfile;
import com.medicare.entity.Role;
import com.medicare.entity.User;
import com.medicare.exception.DoctorNotFoundException;
import com.medicare.exception.UserNotFoundException;
import com.medicare.repository.DoctorProfileRepository;
import com.medicare.repository.UserRepository;

@Service
public class DoctorService {

    private final DoctorProfileRepository doctorRepository;
    private final UserRepository userRepository;

    public DoctorService(
            DoctorProfileRepository doctorRepository,
            UserRepository userRepository) {

        this.doctorRepository = doctorRepository;
        this.userRepository = userRepository;
    }

    public DoctorResponse createDoctor(DoctorProfileRequest request) {

        User user = findUserById( request.getUserId() );

        if (user.getRole() != Role.DOCTOR) {

            throw new IllegalArgumentException(
                    "Doctor profile can only be created for a DOCTOR user"
            );
        }

        if (doctorRepository.existsByUserId(user.getId())) {

            throw new IllegalArgumentException(
                    "Doctor profile already exists for this user"
            );
        }

        DoctorProfile doctor = new DoctorProfile();

        doctor.setUser(user);

        doctor.setSpecialization(
                request.getSpecialization()
        );

        doctor.setExperienceYears(request.getExperienceYears());
        doctor.setConsultationFee(request.getConsultationFee());
        doctor.setPhotoUrl( request.getPhotoUrl());
        DoctorProfile savedDoctor = doctorRepository.save(doctor);
        return mapToDoctorResponse(savedDoctor);
    }

    public List<DoctorResponse> searchDoctors(
          String specialization, BigDecimal maxFee, String name) {
        specialization = normalizeText(specialization);
        
        name = normalizeText(name);

        if (maxFee != null && maxFee.compareTo(BigDecimal.ZERO) <= 0) {
            throw new IllegalArgumentException(
                    "Maximum consultation fee must be greater than zero"
            );
        }

        List<DoctorProfile> doctors = doctorRepository.searchDoctors(
           specialization, maxFee, name);

        List<DoctorResponse> responses = new ArrayList<>();

        for (DoctorProfile doctor : doctors) {
            responses.add(mapToDoctorResponse(doctor));
        }
        return responses;
    }

    public DoctorResponse getDoctorById(Long id) {
        DoctorProfile doctor = findDoctorById(id);
        return mapToDoctorResponse(doctor);
    }

    public DoctorResponse updateDoctor(Long id, DoctorProfileRequest request) {

        DoctorProfile doctor = findDoctorById(id);
        doctor.setSpecialization(request.getSpecialization());
        doctor.setExperienceYears(request.getExperienceYears());
        doctor.setConsultationFee(request.getConsultationFee());
        doctor.setPhotoUrl(request.getPhotoUrl());
        DoctorProfile updatedDoctor =doctorRepository.save(doctor);
        return mapToDoctorResponse(updatedDoctor);
    }

    public void deleteDoctor(Long id) {
        DoctorProfile doctor = findDoctorById(id);
        doctorRepository.delete(doctor);
    }

    private DoctorProfile findDoctorById(Long id) {

        return doctorRepository.findById(id).orElseThrow(() ->
                        new DoctorNotFoundException("Doctor not found with id: "
                          + id));
    }

    private User findUserById(Long id) {

        return userRepository
                .findById(id)
                .orElseThrow(() ->
                        new UserNotFoundException(
                                "User not found with id: " + id
                        )
                );
    }

    /*
     * Converts DoctorProfile entity into the simpler
     * response sent to the frontend.
     */
    private DoctorResponse mapToDoctorResponse(
            DoctorProfile doctor) {

        return new DoctorResponse(
                doctor.getId(),
                doctor.getUser().getName(),
                doctor.getSpecialization(),
                doctor.getExperienceYears(),
                doctor.getConsultationFee(),
                doctor.getPhotoUrl()
        );
    }

    /*
     * Empty request parameters should behave
     * the same as parameters that were not supplied.
     */

    private String normalizeText(String value) {
        if (value == null || value.isBlank()) {
            return null;
        }
        return value.trim();
    }
}

Why normalizeText()?

Suppose React accidentally sends: GET /api/doctors?name=

Technically: name = "" rather than: null

We convert:

""
" "
"     "

null

so those empty filters don't affect the query.

Update DoctorController

Our previous:

@GetMapping
public ResponseEntity<List<DoctorProfile>>
getAllDoctors()

will now become dynamic.

package com.medicare.controller;
import java.math.BigDecimal;
import java.util.List;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import com.medicare.dto.DoctorProfileRequest;
import com.medicare.dto.DoctorResponse;
import com.medicare.service.DoctorService;

import jakarta.validation.Valid;

@RestController
@RequestMapping("/api/doctors")
public class DoctorController {

    private final DoctorService doctorService;

    public DoctorController(DoctorService doctorService) {

        this.doctorService = doctorService;
    }

    @PostMapping
    public ResponseEntity<DoctorResponse>
            createDoctor(@Valid @RequestBodyDoctorProfileRequest request) {
        DoctorResponse savedDoctor = doctorService.createDoctor(request);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedDoctor);
    }

    @GetMapping
    public ResponseEntity<List<DoctorResponse>>
            searchDoctors(
                    @RequestParam(required = false)
                    String specialization,

                    @RequestParam(required = false)
                    BigDecimal maxFee,

                    @RequestParam(required = false)
                    String name) {
        List<DoctorResponse> doctors =
                doctorService.searchDoctors(specialization,maxFee,name);
        return ResponseEntity.ok(doctors);
    }

    @GetMapping("/{id}")
    public ResponseEntity<DoctorResponse>
            getDoctorById(@PathVariable Long id) {

        return ResponseEntity.ok(
                doctorService.getDoctorById(id)
        );
    }

    @PutMapping("/{id}")
    public ResponseEntity<DoctorResponse>
            updateDoctor(
                    @PathVariable Long id,
                    @Valid
                    @RequestBody
                    DoctorProfileRequest request) {

        return ResponseEntity.ok(doctorService.updateDoctor(id,request)
        );
    }

    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteDoctor(@PathVariable Long id) {

        doctorService.deleteDoctor(id);

        return ResponseEntity.noContent().build();
    }
}

We've kept: GET /api/doctors as the main doctor-list endpoint.

/api/doctors/all
/api/doctors/filter
/api/doctors/search
/api/doctors/by-name
/api/doctors/by-fee

We didn't create:

That would unnecessarily clutter the API.

Test: Get All Doctors

Our previous:

GET http://localhost:8080/api/doctors

Expected :

Search by Specialization

GET http://localhost:8080/api/doctors?specialization=Cardiologist

200 OK

Expected:

[
    {

        "id": 1,
        "name": "Dr. Ananya Sharma",
        "specialization": "Cardiologist",
        "experienceYears": 8,
        "consultationFee": 1200.00,
        "photoUrl": "https://example.com/ananya.jpg"
    }
]

Search by Doctor Name

GET
http://localhost:8080/api/doctors?name=ananya

Filter by Maximum Fee

GET
http://localhost:8080/api/doctors?maxFee=1000

Suppose:

Dr. Rohan     ₹700
Dr. Priya     ₹900
Dr. Ananya    ₹1200
Dr. Arjun     ₹1500

Result:

Dr. Rohan

Dr. Priya

Dr. Ananya

Dr. Arjun

Combine Filters

GET /api/doctors?specialization=Cardiologist&maxFee=1500&name=ananya

The result must satisfy all three conditions

Search With Only Two Filters

GET /api/doctors?specialization=Cardiologist&maxFee=1300

Filters are optional, so this also works:

Invalid Maximum Fee

GET /api/doctors?maxFee=-500

Filters are optional, so this also works:

Our service detects:

maxFee.compareTo(BigDecimal.ZERO) <= 0

and throws:

IllegalArgumentException

which our existing global handler converts into:

400 BAD REQUEST

What If No Doctor Matches?

Suppose

GET /api/doctors?specialization=SpaceDoctor

No matches.

Should we return: 404 NOT FOUND

No : We should return: 200 OK

Why? - Because the collection /api/doctors exists. The search simply returned zero matches.

We are done with this lab. The latest source code has been uploaded to GitHub. You can access the latest commit using the link below:

Github_repository_link

Great job!

You have successfully implemented doctor search and dynamic filtering in the Medicare backend using Spring Data JPA, custom queries, and DTOs.

Checkpoint

Git Push

git push origin branchName

Next-Lab Preparation

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