我正在使用Flyway尝试创建,然后在Spring Boot Web应用程序启动时播种数据库。 Flyway在第一次迁移中成功创建了数据库表,但由于NullPointerException而未能在第二次填充中。
这是位于软件包db.migration中的迁移代码,称为V2_seed_database.java:
package db.migration;
import org.flywaydb.core.api.migration.BaseJavaMigration;
import org.flywaydb.core.api.migration.Context;
import net.tekknow.medaverter.db.seeds.AppointmentSeeder;
public class V2__seed_database extends BaseJavaMigration {
public void migrate(Context context) {
AppointmentSeeder appointmentSeeder = new AppointmentSeeder();
appointmentSeeder.seed();
}
}
这是AppointmentSeeder代码:
package net.tekknow.medaverter.db.seeds;
import org.json.JSONArray;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import net.tekknow.medaverter.domain.Appointment;
import net.tekknow.medaverter.service.AppointmentService;
@Service
public class AppointmentSeeder {
@Autowired
AppointmentService appointmentService;
@PostConstruct
public void seed() {
String json = "[" +
"{\"id\":1,\"patient_id\":1,\"dateTime\":\"10/29/2010\",\"physician_id\":1,\"lab_id\":1,\"note_id\":0}" +
"]";
org.json.JSONArray appointments = new JSONArray(json);
for (int i=0; i<appointments.length(); i++) {
JSONObject appointment = appointments.getJSONObject(i);
Appointment dbAppointment = new Appointment();
dbAppointment.setId(appointment.getInt("id"));
dbAppointment.setPatientId(appointment.getInt("patient_id"));
dbAppointment.setDateTime(appointment.getString("dateTime"));
dbAppointment.setPhysicianId(appointment.getInt("physician_id"));
dbAppointment.setLabId(appointment.getInt("lab_id"));
dbAppointment.setNoteId(appointment.getInt("note_id"));
appointmentService.save(dbAppointment);
}
}
}
这是AppointmentRepository代码:
package net.tekknow.medaverter.db;
import org.springframework.data.jpa.repository.JpaRepository;
import net.tekknow.medaverter.domain.Appointment;
public interface AppointmentRepository extends JpaRepository<Appointment,Integer> {
}
这是AppointmentService代码:
package net.tekknow.medaverter.service;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import net.tekknow.medaverter.db.AppointmentRepository;
import net.tekknow.medaverter.domain.Appointment;
@Service
@Transactional
public class AppointmentService {
@Autowired
AppointmentRepository repo;
public void save(Appointment appointment) {
System.out.println("AppointmentService.save: appointment="+appointment.toString());
repo.save(appointment); //its failing here
}
}
这是约会bean:
package net.tekknow.medaverter.domain;
import javax.persistence.*;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;
@Entity
@Table(name = "appointments")
public class Appointment {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@NotBlank
@Column(unique = true)
private int patient_id;
@Size(max = 32)
private String date_time;
private int physician_id;
private int lab_id;
private int note_id;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
... other getters and setters, truncated for brevity
当我运行程序时,迁移开始但在此行失败:
repo.save(appointment); //its failing here
,并显示以下错误消息:
由以下原因引起:java.lang.NullPointerException:在null net.tekknow.medaverter.service.AppointmentService.save(AppointmentService.java:32) 〜[classes /:na]
仅在失败的代码行之前,我输出它说为null且不为null的对象的内容:
AppointmentService.save:约会= ID:1,患者ID:1, date_time:10/29/2010,doctor_id:1,lab_id:1,note_id:0
有什么建议吗?
答案 0 :(得分:1)
这与休眠无关,您以错误的方式使用了Spring依赖项注入:您试图自动装配静态字段,这是不允许的。
请参见Can you use @Autowired with static fields?。
更新
现在您有
AppointmentService appointmentService = new AppointmentService();
而不是将此字段注入到Seeder。
如果要使依赖项注入起作用, Seeder必须是一个Spring管理的bean(可能是@Service
)。另请参见@PostConstruct
,您可以在初始化bean之后使用它来调用方法。
更新2
您仍在自己使用new
实例化Spring Bean,因此不会注入依赖项。
AppointmentSeeder appointmentSeeder = new AppointmentSeeder();
但是,您已经成功地将问题推向了Flyway。现在的问题是Flyway迁移不是Spring Bean:它们是由Flyway而非Spring创建的,因此它们的依赖项不会由Spring自动关联。
Flyway 4.1通过允许使用带有一些配置的预先存在的Spring Bean(或其他Java对象)解决了这个问题
请参见API: Make it possible to use pre-instantiated Java-based migrations #1062。
ApplicationContext applicationContext = ...; // obtain a reference to Spring's ApplicationContext. Flyway flyway = Flyway.configure() .dataSource(url, user, password) // Add all Spring-instantiated JavaMigration beans .javaMigrations(applicationContext.getBeansOfType(JavaMigration.class).values().toArray(new JavaMigration[0])) .load(); flyway.migrate();
另请参见JavaMigration和BaseJavaMigration Javadoc。
答案 1 :(得分:0)
也许您应该将JSON文件中的** note_id **的值更改为 1 !
答案 2 :(得分:0)
在AppointmentSeeder中执行此操作,
xcode-select --install