[FIXED] No implementation type is registered for return type org.springframework.data.domain.Page<DTO>

Issue

im developing a spring boot application in java, and when i was trying to implement pagination on my application, i had to add a Page converter to my custom mapper, but got this error:

(java: No implementation type is registered for return type org.springframework.data.domain.Page<com.celulaweb.crud.service.dto.CidadeDTO>.)

I was wondering why am i getting the error, since the List converter works just fine.

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.celulaweb</groupId>
    <artifactId>crud</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>crud</name>
    <description>Crud Estudo CelulaWeb</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.modelmapper</groupId>
            <artifactId>modelmapper</artifactId>
            <version>3.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct</artifactId>
            <version>1.4.1.Final</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.liquibase</groupId>
            <artifactId>liquibase-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-commons</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>1.1.0.Final</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.8.1</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.liquibase</groupId>
                <artifactId>liquibase-maven-plugin</artifactId>
                <version>3.4.1</version>
                <configuration>
                    <outputChangeLogFile>src/main/resources/liquibase-outputChangeLog.xml</outputChangeLogFile>
                    <url>jdbc:mysql://localhost/crud</url>
                    <username>root</username>
                    <password>root</password>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <encoding>UTF-8</encoding>
                    <source>1.8</source>
                    <target>1.8</target>
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                            <version>${lombok.version}</version>
                        </path>
                        <path>
                            <groupId>org.mapstruct</groupId>
                            <artifactId>mapstruct-processor</artifactId>
                            <version>1.4.1.Final</version>
                        </path>
                    </annotationProcessorPaths>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

CustomMapper.java

package com.celulaweb.crud.service.mappers;

import com.celulaweb.crud.domain.Cidade;
import com.celulaweb.crud.service.dto.CidadeDTO;
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.springframework.data.domain.Page;
import org.springframework.stereotype.Component;

import java.util.List;

@Component
@Mapper(componentModel = "spring")
public interface CidadeMapper {

    @Mapping(source = "id", target = "id")
    @Mapping(source = "nome", target = "nome")
    @Mapping(source = "qtdHabitantes", target = "qtdHabitantes")
    @Mapping(source = "estado", target = "estado")
    CidadeDTO cidadeParaDTO(Cidade cidade);
    List<CidadeDTO> cidadeParaDTO(List<Cidade> cidade);
    Page<CidadeDTO> cidadeParaDTO(Page<Cidade> cidade);
    Cidade cidadeDTOParaCidade(CidadeDTO cidadeDTO);

}

Solution

I resolved the error by getting the Page<CidadeDTO> cidadeParaDTO(Page<Cidade> cidade); out of my custom mapper and adding the snippet below to my entity service

public Page<CidadeDTO> listarCidades(Pageable pageable){
    Page<Cidade> cidadePage = cidadeRepository.findAll(pageable);
    List<CidadeDTO> cidadeDTOPage = cidadeMapper.cidadeParaDTO(cidadePage.getContent());
    return new PageImpl<>(cidadeDTOPage, pageable, cidadePage.getTotalElements());
}

that worked for me 😁

Answered By - IgorGarciaRez
Answer Checked By - Terry (JavaFixing Volunteer)