Most modern applications need flexible search functionality — whether it’s filtering products in an e-commerce site, searching users in a CRM, or querying logs in a dashboard. Static SQL or JPA queries quickly become unmanageable when handling dynamic filters.

QueryDSL offers a powerful, type-safe alternative. With its fluent API, you can construct complex queries dynamically while retaining full compiler-time validation.

In this post, we’ll explore how to integrate QueryDSL with Spring Boot, and how to build dynamic, flexible search APIs that scale with your application.

What is QueryDSL?

QueryDSL is a domain-specific language for querying relational databases in a type-safe way. It generates query types (e.g., QUser, QProduct) from your entities and allows for expressive, fluent-style query construction.

Benefits:

  • Type safety at compile time
  • Clean syntax similar to Java streams
  • Support for complex boolean logic, joins, and projections
  • Works seamlessly with Spring Data JPA

Adding QueryDSL to Your Spring Boot Project

To get started, add the following dependencies:

<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-apt</artifactId>
<scope>provided</scope>
</dependency>

Then configure your build plugin (for Maven):

<plugin>
<groupId>com.mysema.maven</groupId>
<artifactId>apt-maven-plugin</artifactId>
<version>1.1.3</version>
<executions>
<execution>
<goals>
<goal>process</goal>
</goals>
<configuration>
<outputDirectory>target/generated-sources/java</outputDirectory>
<processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
</configuration>
</execution>
</executions>
</plugin>

Generated classes (like QUser) will appear in target/generated-sources.

Defining Your Entity

Create a JPA entity for users:

@Entity
public class User {
@Id
@GeneratedValue
private Long id;

    private String name;
    private String email;
    private LocalDate birthdate;
}

QueryDSL will generate QUser for this entity.

Creating a Custom Repository with QueryDSL

Extend QuerydslPredicateExecutor or create a custom implementation:

public interface UserRepository extends JpaRepository<User, Long>,
QuerydslPredicateExecutor<User> {
}

Now you can use dynamic predicates in your services or controllers.

Building Dynamic Predicates

You can compose filters based on request parameters:

public Predicate buildPredicate(String name, String email) {
QUser user = QUser.user;
BooleanBuilder builder = new BooleanBuilder();

    if (name != null) {
        builder.and(user.name.containsIgnoreCase(name));
    }
    if (email != null) {
        builder.and(user.email.containsIgnoreCase(email));
    }

    return builder;
}

Then call it:

public List<User> searchUsers(String name, String email) {
return userRepository.findAll(buildPredicate(name, email));
}

This allows full flexibility without writing custom SQL or JPA queries.

Exposing a Flexible Search API

Create a REST controller:

@RestController
@RequestMapping("/api/users")
public class UserController {

    @Autowired
    private UserRepository userRepository;

    @GetMapping("/search")
    public List<User> searchUsers(
        @RequestParam(required = false) String name,
        @RequestParam(required = false) String email) {
        
        QUser user = QUser.user;
        BooleanBuilder builder = new BooleanBuilder();

        if (name != null) {
            builder.and(user.name.containsIgnoreCase(name));
        }
        if (email != null) {
            builder.and(user.email.containsIgnoreCase(email));
        }

        return (List<User>) userRepository.findAll(builder);
    }
}

Call the API like:

GET /api/users/search?name=john&email=gmail

Adding Pagination and Sorting

QueryDSL supports pagination with Spring’s Pageable interface:

@GetMapping("/search")
public Page<User> search(
@RequestParam(required = false) String name,
@RequestParam(required = false) String email,
Pageable pageable) {

    QUser user = QUser.user;
    BooleanBuilder builder = new BooleanBuilder();

    if (name != null) {
        builder.and(user.name.containsIgnoreCase(name));
    }
    if (email != null) {
        builder.and(user.email.containsIgnoreCase(email));
    }

    return userRepository.findAll(builder, pageable);
}

Advanced Filtering with Query Parameters

You can implement range filters, date filters, or boolean flags:

if (minDate != null) {
builder.and(user.birthdate.goe(minDate));
}
if (maxDate != null) {
builder.and(user.birthdate.loe(maxDate));
}

This makes QueryDSL ideal for building advanced search interfaces or data grids.

Pros and Cons of QueryDSL

Pros:

  • Type-safe, fluent syntax
  • Eliminates boilerplate query strings
  • Dynamic query composition
  • Easy integration with Spring Data

Cons:

  • Requires build configuration for code generation
  • Slight learning curve
  • IDE support varies depending on setup

Conclusion

QueryDSL is a powerful tool that dramatically improves how you write dynamic search logic in Spring Boot applications. By leveraging its type-safe API and BooleanBuilder, you can build APIs that adapt to complex filtering requirements — all while maintaining clean, readable code.

For any Java developer working on search-heavy backends, QueryDSL is a must-have in your Spring toolkit.