GraphQL在查詢時回傳null-有解無憂

第一次嘗試 GraphQL，如果是基本修復，請原諒。

https://i.stack.imgur.com/Hwf8Q.png

我的 API 用于顯示一些從希思羅機場起飛的模擬資料。API 應回傳在 import.sql 檔案中顯示的所有離開。這是使用 Spring 在記憶體資料庫中運行 h2。我的應用程式.properites：

spring.h2.console.enabled=true
spring.h2.console.path=/h2
spring.datasource.url=jdbc:h2:mem:lhrdata

graphql.servlet.mapping=/graphql
graphql.servlet.enabled=true
graphql.servlet.corsEnabled=true

graphiql.enabled=true
graphiql.endpoint=/graphql
graphiql.mapping=graphiql

spring.datasource.username=sa
spring.datasource.password=

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.defer-datasource-initialization=true

物體 > Departure.java

    package com.LHRDepartures.LHROUT.entity;

import javax.persistence.*;
import java.util.Arrays;
import java.util.List;

@Entity
public class Departure {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;
    private String destination;
    private Float arrival_time;
    private String airline;
    private String aircraft_make;
    private String aircraft_model;
    private String terminal;

    public Departure() {
    }

    public Departure(Long id, String destination, Float arrival_time, String airline, String aircraft_make, String aircraft_model, String terminal) {
        this.id = id;
        this.destination = destination;
        this.arrival_time = arrival_time;
        this.airline = airline;
        this.aircraft_make = aircraft_make;
        this.aircraft_model = aircraft_model;
        this.terminal = terminal;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getDestination() {
        return destination;
    }

    public void setDestination(String destination) {
        this.destination = destination;
    }

    public Float getArrival_time() {
        return arrival_time;
    }

    public void setArrival_time(Float arrival_time) {
        this.arrival_time = arrival_time;
    }

    public String getAirline() {
        return airline;
    }

    public void setAirline(String airline) {
        this.airline = airline;
    }

    public String getAircraft_make() {
        return aircraft_make;
    }

    public void setAircraft_make(String aircraft_make) {
        this.aircraft_make = aircraft_make;
    }

    public String getAircraft_model() {
        return aircraft_model;
    }

    public void setAircraft_model(String aircraft_model) {
        this.aircraft_model = aircraft_model;
    }

    public String getTerminal() {
        return terminal;
    }

    public void setTerminal(String terminal) {
        this.terminal = terminal;
    }


}

突變體

package com.LHRDepartures.LHROUT.mutator;

import com.LHRDepartures.LHROUT.entity.Departure;
import com.LHRDepartures.LHROUT.exception.DepartureNotFoundException;
import com.LHRDepartures.LHROUT.repository.DepartureRepository;
import com.coxautodev.graphql.tools.GraphQLMutationResolver;
import org.springframework.stereotype.Component;

import java.util.Optional;


public class Mutation implements GraphQLMutationResolver {
    private DepartureRepository departureRepository;

    public Mutation(DepartureRepository departureRepository){
        this.departureRepository = departureRepository;
    }

    public boolean deleteDeparture(Long ID){
        departureRepository.deleteById(ID);
        return true;
    }
/*
    public Departure updateTerminal(Integer newTerminal, Long Id){
        Optional<Departure> optionalDeparture =
                departureRepository.findById(Id);

        if(optionalDeparture.isPresent()){
            Departure departure = optionalDeparture.get();
          //  departureRepository.setName(newTerminal);
            departureRepository.save(departure);
            return departure;
        } else {
            throw new DepartureNotFoundException("Departure not found!", Id);
        } */
}

存盤庫

package com.LHRDepartures.LHROUT.repository;

import com.LHRDepartures.LHROUT.entity.Departure;
import org.springframework.data.repository.CrudRepository;

public interface DepartureRepository extends CrudRepository<Departure, Long> {

}

詢問

package com.LHRDepartures.LHROUT.resolver;

import com.LHRDepartures.LHROUT.entity.Departure;
import com.LHRDepartures.LHROUT.repository.DepartureRepository;
import org.springframework.stereotype.Component;

@Component
public class Query {
    private DepartureRepository departureRepository;

    public Query(DepartureRepository departureRepository){
        this.departureRepository = departureRepository;
    }

    public Iterable<Departure> findAllDepartures() {
        return departureRepository.findAll();
    }
}

服務

package com.LHRDepartures.LHROUT.service;

import com.LHRDepartures.LHROUT.entity.Departure;
import org.springframework.stereotype.Service;

import java.util.List;

public interface DepartureService {
    List<Departure> retrieveDeparture();
}

控制器

package com.LHRDepartures.LHROUT.web;

import com.LHRDepartures.LHROUT.entity.Departure;
import com.LHRDepartures.LHROUT.service.DepartureService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class DepartureController {
    private DepartureService departureService;

    @Autowired
    public void setDepartureService(DepartureService departureService){
        this.departureService = departureService;
    }

    @GetMapping("/departure")
    public ResponseEntity<List<Departure>> getAllDeparture(){
        List<Departure> list = departureService.retrieveDeparture();
        return new ResponseEntity<List<Departure>>(list, HttpStatus.OK);
    }

}

GraphQL 架構：

type Departure{
    id: ID!
    destination  : String!
    arrival_time : Float!
    airline : String!
    aircraft_make : String
    aircraft_model : String
    terminal : String!
}

type Query {
    findAllDepartures: [Departure]
}

type Mutation {
    deleteDeparture(id:ID) : Boolean
    updateTerminal(newTerminal : String, id:ID!): Departure!

}

匯入.sql

INSERT INTO departure (id, destination, arrival_time, airline, aircraft_make, aircraft_model, terminal) VALUES (1, 'LAX - Los Angeles Intl.', '1234', 'British Airways', 'AIRBUS', 'A380', '5');
INSERT INTO departure (id, destination, arrival_time, airline, aircraft_make, aircraft_model, terminal) VALUES (2, 'JFK - New York John F. Kennedy Intl.', '1345', 'British Airways', 'BOEING', '777-300', '5');
INSERT INTO departure (id, destination, arrival_time, airline, aircraft_make, aircraft_model, terminal) VALUES (3, 'MAN - Manchester Intl.', '1400', 'British Airways', 'AIRBUS', 'A319', '5');
INSERT INTO departure (id, destination, arrival_time, airline, aircraft_make, aircraft_model, terminal) VALUES (4, 'FRA - Frankfurt Intl.', '1521', 'Lufthansa', 'AIRBUS', 'A319', "3');
INSERT INTO departure (id, destination, arrival_time, airline, aircraft_make, aircraft_model, terminal) VALUES (5, 'CPT - Cape Town Intl.', '1605', 'Virgin Atlantic', 'BOEING', '787-900', '2');
INSERT INTO departure (id, destination, arrival_time, airline, aircraft_make, aircraft_model, terminal) VALUES (6, 'LAX - Los Angeles Intl.', '1634', 'British Airways', 'BOEING', '777-300', '5');

我知道那里有很多東西，但我很困惑。任何幫助表示贊賞。

uj5u.com熱心網友回復：

目前，您沒有將您的 graphql 服務器和業務邏輯粘合在一起的代碼。

幸運的是，Spring Boot 提供了與 Spring Boot for GraphQL 專案的無縫集成 GraphQL 集成。

為了開始使用它，只需將以下依賴項添加到您的構建工具中。

implementation 'org.springframework.boot:spring-boot-starter-graphql'

然后，您需要將架構添加到以下位置：

resources/graphql/schema.graphqls

您的架構定義看起來不錯，因此添加到此位置時它將起作用

最后，您需要定義一個控制器，它將您的業務邏輯系結到 graphql 服務器。

    import com.example.graphql.departure.model.Departure;
import com.example.graphql.departure.model.DepartureRepository;
import org.springframework.graphql.data.method.annotation.QueryMapping;
import org.springframework.stereotype.Controller;

@Controller
public class DepartureController {

    private final DepartureRepository departureRepository;

    public DepartureController(DepartureRepository departureRepository) {
        this.departureRepository = departureRepository;
    }

    @QueryMapping
    public Iterable<Departure> findAllDepartures() {
        return departureRepository.findAll();

    }
}

檢查如何使用 @QueryMapping 注解來定義有效的 graphql 查詢。

然后，如果你運行一切，你應該能夠看到結果。

查看此示例專案以獲取參考https://github.com/CaptainAye/graphql-sample

轉載請註明出處，本文鏈接：https://www.uj5u.com/ruanti/518070.html

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