如何加入自定义查询spring boot答案

【问题标题】：How to join custom queries spring boot如何加入自定义查询spring boot
【发布时间】：2022-01-08 23:41:25
【问题描述】：

我需要创建一个端点，通过城市列表按州返回人口普查数据，我目前使用两个端点来获取。

目前的回应：

自定义查询一：censusByState

[
    {
        "id": 1,
        "code": 11,
        "name": "Rondônia",
        "statePopulation": 1815278,
        "countCities": 52
    },
    {
        "id": 2,
        "code": 12,
        "name": "Acre",
        "statePopulation": 906876,
        "countCities": 22
    },
    {...
     },
    {
        "id": 27,
        "code": 53,
        "name": "Distrito Federal",
        "statePopulation": 3094325,
        "countCities": 1
    }
]

自定义查询二：censusCitiesByState

[
    {
        "code": 1100015,
        "name": "Alta Floresta d Oeste",
        "cityPopulation": 22516
    },
    {
        "code": 1100023,
        "name": "Ariquemes",
        "cityPopulation": 111148
    },
    {...
    },
    {
        "code": 1101807,
        "name": "Vale do Paraíso",
        "cityPopulation": 6490
    }
]

预期响应：

[
    {
        "id": 1,
        "code": 11,
        "name": "Rondônia",
        "statePopulation": 1815278,
        "countCities": 52,
        "cities": [
            {
                "code": 1100015,
                "name": "Alta Floresta d Oeste",
                "cityPopulation": 22516
            },
            {...
            },
            {
                "code": 1101807,
                "name": "Vale do Paraíso",
                "cityPopulation": 6490
            }
        ]
    },
    {...
    },
    {
        "id": 2,
        "code": 12,
        "name": "Acre",
        "statePopulation": 906876,
        "countCities": 22,
        "cities":[
             {
                "code": 1200013,
                "name": "Acrelândia",
                "cityPopulation": 15721
            },
            {...
            },
            {
                "code": 1200807,
                "name": "Porto Acre",
                "cityPopulation": 19141
            }
        ]

    }
]

你能帮帮我吗？

我的课：

型号

状态

package com.example.demo.model;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

@Entity
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "states")
@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class State {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private Integer code;
    private String name;

    @Column(length = 2)
    private String uf;

}

城市

package com.example.demo.model;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

@Entity
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "cities")
@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class City {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "state_id", nullable = false, foreignKey = @ForeignKey(name = "fk_cities_states1"))
    private State state;
    private String  code;
    private String name;

}

人口普查

package com.example.demo.model;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

@Entity
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "census_population")
@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class CensusPopulation {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "census_id", nullable = false, foreignKey = @ForeignKey(name = "fk_census_population_census1"))
    private Census census;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "city_id", nullable = false, foreignKey = @ForeignKey(name = "fk_census_population_cities1"))
    private City city;
    private Long  population;

}

界面

CensusStateStats

package com.example.demo.dto;

public interface CensusStateStats {
    Long getId();
    Integer getCode();
    String getName();
    Long getStatePopulation();
    Long getCountCities();
}

CensusStateCitiesStats

package com.example.demo.dto;

public interface CensusStateCitiesStats {
    Integer getCode();
    String getName();
    Long getCityPopulation();
}

DTO

CensusStateStatsDto

package com.example.demo.dto;

import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
public class CensusStateStatsDto {
    private Long id;
    private Integer code;
    private String name;
    private Long statePopulation;
    private long countCities;

    public CensusStateStatsDto(CensusStateStats censusStateStatsDto) {
        this.id = censusStateStatsDto.getId();
        this.code = censusStateStatsDto.getCode();
        this.name = censusStateStatsDto.getName();
        this.statePopulation = censusStateStatsDto.getStatePopulation();
        this.countCities = censusStateStatsDto.getCountCities();
    }

}

CensusStateCitiesStatsDto

package com.example.demo.dto;

import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
public class CensusStateCitiesStatsDto {
    private Integer code;
    private String name;
    private Long cityPopulation;

    public CensusStateCitiesStatsDto(CensusStateCitiesStats censusStateCitiesStats) {
        this.code = censusStateCitiesStats.getCode();
        this.name = censusStateCitiesStats.getName();
        this.cityPopulation = censusStateCitiesStats.getCityPopulation();
    }
}

存储库

CensusPopulationRep

package com.example.demo.repository;

import com.example.demo.dto.CensusStateCitiesStats;
import com.example.demo.dto.CensusStateStats;
import com.example.demo.model.CensusPopulation;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

import java.util.List;

public interface CensusPopulationRep extends JpaRepository<CensusPopulation, Long> {

    @Query(value = "SELECT s.id, s.code, s.name, s.uf, " +
            "SUM(cp.population) AS statePopulation, " +
            "COUNT(cp.id) AS countCities, " +
            "FROM census_population cp " +
            "INNER JOIN cities c ON c.id = cp.city_id " +
            "INNER JOIN states s ON s.id = c.state_id " +
            "GROUP BY s.code, s.name, s.uf"
            , nativeQuery = true)
    List<CensusStateStats> censusByState();

    @Query(value = "SELECT c.code, c.name, " +
            "SUM(cp.population) AS cityPopulation, " +
            "FROM census_population cp " +
            "INNER JOIN cities c ON c.id = cp.city_id " +
            "WHERE c.state_id = :state " +
            "GROUP BY c.code, c.name "
            , nativeQuery = true)
    List<CensusStateCitiesStats> censusCitiesByState(@Param("state") Long state);

}

服务

人口普查服务

package com.example.demo.service;

import com.example.demo.dto.CensusStateCitiesStats;
import com.example.demo.dto.CensusStateStats;
import com.example.demo.model.CensusPopulation;
import com.example.demo.repository.CensusPopulationRep;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
@RequiredArgsConstructor
public class CensusPopulationService {

    private final CensusPopulationRep censusPopulationRep;

    public List<CensusPopulation> findAll() {
        return censusPopulationRep.findAll();
    }

    public List<CensusStateStats> censusByState() {
        return censusPopulationRep.censusByState();
    }

    public List<CensusStateCitiesStats> censusCitiesByState(Long state) {
        return censusPopulationRep.censusCitiesByState(state);
    }
}

控制器

人口普查控制器

package com.example.demo.controller;

import com.example.demo.dto.CensusStateCitiesStatsDto;
import com.example.demo.dto.CensusStateStatsDto;
import com.example.demo.model.CensusPopulation;
import com.example.demo.service.CensusPopulationService;
import lombok.RequiredArgsConstructor;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.stream.Collectors;

@RestController
@RequestMapping("api/v1/census-population")
@RequiredArgsConstructor
public class CensusPopulationController {

    private final CensusPopulationService censusPopulationService;

    @GetMapping
    public ResponseEntity<List<CensusPopulation>> findAll() {
        return ResponseEntity.ok(censusPopulationService.findAll());
    }

    @GetMapping("/state-stats")
    public ResponseEntity<List<CensusStateStatsDto>> censusByState() {
        return ResponseEntity.ok(censusPopulationService.censusByState().stream()
                .map(CensusStateStatsDto::new)
                .collect(Collectors.toList()));
    }

    @GetMapping("/state-cities-stats")
    public ResponseEntity<List<CensusStateCitiesStatsDto>> censusCitiesByState(@RequestParam(required = false) Long state) {
        return ResponseEntity.ok(censusPopulationService.censusCitiesByState(state).stream()
                .map(CensusStateCitiesStatsDto::new)
                .collect(Collectors.toList()));
    }
}

【问题讨论】：

你想加入自定义查询还是通过多个数据库调用获取数据可以吗？
我想加入自定义查询，最终过滤一个州并列出该州的城市
那么这更像是一个 SQL 问题，而不是 Java 或 Spring Boot。
谢谢João，这次我会使用Hassan的建议

标签： java sql spring-boot

【解决方案1】：

您可以创建一个新类StateCityCensusDto，然后在查询censusCitiesByState 时也返回stateId

@Data
public class StateCityCensusDto {

    private StateCensus stateCensus;
    private List<CityCensus> cities;

}

    Integer getCode();
    String getName();
    Long getCityPopulation();
    //add stateId retrieve from query
    Long getStateId();
}

然后返回城市旁边的州。


      List<CensusStateStats> stateCensusList = //retrieve from the db;
      List<CensusStateCitiesStats>  //retrieve from the db;
      List<StateCityCensusDto> stateCityCensusList = new ArrayList<>();

    stateCensusList.forEach(stateCensus -> {
         StateCityCensusDto stateCityCensus = new StateCityCensusDto();
         stateCityCensus.setStateCensus(stateCensus);
         stateCityCensus.setCities(cityCensusList.stream()
                  .filter(c -> c.getStateId() == stateCensus.getId())
                  .collect(Collectors.toList()));
                   
        stateCityCensusList.add(stateCityCensus);
    });

【讨论】：

非常感谢 Hassan 的帮助，这正是我想要的。
不客气 :)