多对多ormlite问题

编程问答 2022-06-11

问题描述

我使用的数据库是ormlite。 这是一个用于存储项目，开发人员的数据库，另一个用于存储项目与开发人员之间的多对多关系的数据库。 但是当我想使用示例开发人员的名称时，它们为null。 谢谢你。

DatabaseHelper helper = DatabaseManager.getDatabaseHelper(this);
        DeveloperEntity developerEntity = new DeveloperEntity("ahmad","java",null);
        try {
            helper.getDeveloperDao().createOrUpdate(developerEntity);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        ProjectEntity projectEntity = new ProjectEntity("acopal",null);
        try {
            helper.getProjectDao().createOrUpdate(projectEntity);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        DeveloperProjectEntity developerProjectEntity = new DeveloperProjectEntity(developerEntity,projectEntity);
        try {
            helper.getDeveloperProjectDao().createOrUpdate(developerProjectEntity);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
             developerProjectEntityList = DatabaseManager.getDatabaseHelper(this)
                    .getDeveloperProjectDao().
                            queryForAll();
        } catch (SQLException e) {
            e.printStackTrace();
        }

package com.example.acopaldatabase.database.model;

import com.j256.ormlite.field.DatabaseField;
import com.j256.ormlite.table.DatabaseTable;

import java.io.Serializable;

@DatabaseTable(tableName = "developer_project")
public class DeveloperProjectEntity implements Serializable {


    @DatabaseField(generatedId = true)
    private int id;

    @DatabaseField(foreign = true,columnName = "developer_id",canBeNull = false)
    private DeveloperEntity developer;

    @DatabaseField(foreign = true,columnName = "project_id",canBeNull = false)
    private ProjectEntity project;


    public DeveloperProjectEntity() {
    }


    public DeveloperProjectEntity(DeveloperEntity developer,ProjectEntity project) {
        this.developer = developer;
        this.project = project;
    }




    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }


    public DeveloperEntity getDeveloper() {
        return developer;
    }
    public void setDeveloper(DeveloperEntity developer) {
        this.developer = developer;
    }



    public ProjectEntity getProject() {
        return project;
    }
    public void setProject(ProjectEntity project) {
        this.project = project;
    }
}

查看调试结果： 这是图片，请打开它

Debug Result

解决方法

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androidandroiddatabasejavajavaormlite