在线教育项目-day08【最终发布】

最终需要查询到课程名称、封面、分类、讲师、简介、价格等信息，需要我们去查询多张表

有三种多表连接

1.内连接

2.左外连接

3.右外连接

我们使用左外连接，因为可能有数据为空的情况

最终一个sql语句：

select ec.id,
ec.title,
ec.price,
ec.lesson_num,
ecd.description,
et.name,
es1.title as oneSubject,
es2.title as twoSubject
from edu_course ec
left outer join edu_course_description ecd on ec.id=ecd.id
left outer join edu_teacher et on ec.teacher_id=et.id
left outer join edu_subject es1 on ec.subject_parent_id=es1.id 
left outer join edu_subject es2 on ec.subject_id=es2.id
where ec.id=1256870825265496066

 sql语句写完了，我们来整理后端

先创建一个实体类

@Data
public class CoursePublishVo {
    private String id;
    private String title;
    private String cover;
    private Integer lessonNum;
    private String subjectLevelOne;
    private String subjectLevelTwo;
    private String teacherName;
    private String price;//只用于显示
}

根据我们创建的实体类书写mapper

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.dm.eduservice.mapper.EduCourseMapper">
    <!--sql语句根据k课程id查询对应信息-->
    <select id="getPublishCourseInfo" resultType="com.dm.eduservice.entity.vo.CoursePublishVo">
        select ec.id,
        ec.title,
        ec.cover,
        ec.lesson_num as lessonNum,
        es1.title as subjectLevelOne,
        es2.title as subjectLevelTwo,
        et.name as teacherName,
        ec.price
        from edu_course ec
        left outer join edu_course_description ecd on ec.id=ecd.id
        left outer join edu_teacher et on ec.teacher_id=et.id
        left outer join edu_subject es1 on ec.subject_parent_id=es1.id
        left outer join edu_subject es2 on ec.subject_id=es2.id
        where ec.id=#{courseId}
    </select>
</mapper>

书写controller方法

    //根据课程id查询课程确认信息
    @GetMapping("getPublishCourseInfo/{id}")
    public R getPublishCourseInfo(@PathVariable String id) {
        CoursePublishVo coursePublishVo = courseService.publishCourseInfo(id);
        return R.OK().data("publishCourse",coursePublishVo);
    }

serviceimpl

    @Override
    public CoursePublishVo publishCourseInfo(String id) {
        CoursePublishVo publishCourseInfo = baseMapper.getPublishCourseInfo(id);
        return publishCourseInfo;
    }

这里出现了一个问题

测试：报告异常

AbstractHandlerExceptionResolver.java:194 |org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver |Resolved exception caused by handler execution: org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.guli.edu.mapper.CourseMapper.getCoursePublishVoById

原因分析

dao层编译后只有class文件，没有mapper.xml，因为maven工程在默认情况下src/main/java目录下的所有资源文件是不发布到target目录下的，

解决方法：

1.把xml复制到target文件夹中

2.把xml文件放在resourse文件jia下

3.通过配置（推荐）

（1）在pom.xml中设置

（2）application.properties配置

1.  

2. 

 

 再编译可以看到已经有了xml的文件

测试成功

 前端

先在course.js中添加接口

    //课程提交
    getPublishCourseInfo(id){
        return request({
            url: '/eduservice/edu-course/getPublishCourseInfo/'+id,
            method: 'get',

          })
    }

然后书写页面

<template>

  <div class="app-container">

    <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="3" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="最终发布"/>
    </el-steps>
    <div class="ccInfo">
      <img :src="coursePublish.cover">
      <div class="main">
        <h2>{{ coursePublish.title }}</h2>
        <p class="gray"><span>共{{ coursePublish.lessonNum }}课时</span></p>
        <p><span>所属分类：{{ coursePublish.subjectLevelOne }} — {{ coursePublish.subjectLevelTwo }}</span></p>
        <p>课程讲师：{{ coursePublish.teacherName }}</p>
        <h3 class="red">￥{{ coursePublish.price }}</h3>
      </div>
    </div>
     <div>
      <el-button @click="previous">返回修改</el-button>
      <el-button :disabled="saveBtnDisabled" type="primary" @click="publish">发布课程</el-button>
    </div>
  </div>
</template>

<script>
import course from '@/api/course/course'
export default {
  data() {
    return {
      saveBtnDisabled: false, // 保存按钮是否禁用
      courseId:'',
      coursePublish:{}
    }
  },
  created() {
    console.log('publish created')
    if(this.$route.params&&this.$route.params.id){
        this.courseId=this.$route.params.id
        this.getPublishCourseInfo()
    }
  },

  methods: {
    getPublishCourseInfo(){
      course.getPublishCourseInfo(this.courseId)
        .then(response=>{
         this.coursePublish=response.data.publishCourse
        })
    },

    previous() {
      console.log('previous')
      this.$router.push({ path: '/course/chapter/'+this.courseId })
    },

    publish() {
      console.log('publish')
      this.$router.push({ path: '/course/list'+this.courseId })
    }
  }
}
</script>
<style scoped>
.ccInfo {
    background: #f5f5f5;
    padding: 20px;
    overflow: hidden;
    border: 1px dashed #DDD;
    margin-bottom: 40px;
    position: relative;
}
.ccInfo img {
    background: #d6d6d6;
     500px;
    height: 278px;
    display: block;
    float: left;
    border: none;
}
.ccInfo .main {
    margin-left: 520px;
}

.ccInfo .main h2 {
    font-size: 28px;
    margin-bottom: 30px;
    line-height: 1;
    font-weight: normal;
}
.ccInfo .main p {
    margin-bottom: 10px;
    word-wrap: break-word;
    line-height: 24px;
    max-height: 48px;
    overflow: hidden;
}

.ccInfo .main p {
    margin-bottom: 10px;
    word-wrap: break-word;
    line-height: 24px;
    max-height: 48px;
    overflow: hidden;
}
.ccInfo .main h3 {
    left: 540px;
    bottom: 20px;
    line-height: 1;
    font-size: 28px;
    color: #d32f24;
    font-weight: normal;
    position: absolute;
}
</style>

因为我们数据库中默认都是一个未发布状态

所以我们要修改这个状态

后端：

    //课程最终提交
    @PostMapping("publicCourse/{id}")
    public R publicCourse(@PathVariable String id) {
        EduCourse eduCourse=new EduCourse();
        eduCourse.setId(id);
        eduCourse.setStatus("Normal");
        courseService.updateById(eduCourse);
        return R.OK();
    }

前端：

    //发布课程
    publicCourse(id){
        return request({
            url: '/eduservice/edu-course/publicCourse/'+id,
            method: 'post',

          })
    }

<template>

  <div class="app-container">

    <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="3" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="最终发布"/>
    </el-steps>
    <div class="ccInfo">
      <img :src="coursePublish.cover">
      <div class="main">
        <h2>{{ coursePublish.title }}</h2>
        <p class="gray"><span>共{{ coursePublish.lessonNum }}课时</span></p>
        <p><span>所属分类：{{ coursePublish.subjectLevelOne }} — {{ coursePublish.subjectLevelTwo }}</span></p>
        <p>课程讲师：{{ coursePublish.teacherName }}</p>
        <h3 class="red">￥{{ coursePublish.price }}</h3>
      </div>
    </div>
     <div>
      <el-button @click="previous">返回修改</el-button>
      <el-button :disabled="saveBtnDisabled" type="primary" @click="publish">发布课程</el-button>
    </div>
  </div>
</template>

<script>
import course from '@/api/course/course'
export default {
  data() {
    return {
      saveBtnDisabled: false, // 保存按钮是否禁用
      courseId:'',
      coursePublish:{}
    }
  },
  created() {
    console.log('publish created')
    if(this.$route.params&&this.$route.params.id){
        this.courseId=this.$route.params.id
        this.getPublishCourseInfo()
    }
  },

  methods: {
    getPublishCourseInfo(){
      course.getPublishCourseInfo(this.courseId)
        .then(response=>{
         this.coursePublish=response.data.publishCourse
        })
    },

    previous() {
      console.log('previous')
      this.$router.push({ path: '/course/chapter/'+this.courseId })
    },

    publish() {
      course.publicCourse(this.courseId)
        .then(response=>{
            this.$message({
                        type: 'success',
                        message: '课程发布成功!'
                    });

        })
      this.$router.push({ path: '/course/list' })
    }
  }
}
</script>
<style scoped>
.ccInfo {
    background: #f5f5f5;
    padding: 20px;
    overflow: hidden;
    border: 1px dashed #DDD;
    margin-bottom: 40px;
    position: relative;
}
.ccInfo img {
    background: #d6d6d6;
     500px;
    height: 278px;
    display: block;
    float: left;
    border: none;
}
.ccInfo .main {
    margin-left: 520px;
}

.ccInfo .main h2 {
    font-size: 28px;
    margin-bottom: 30px;
    line-height: 1;
    font-weight: normal;
}
.ccInfo .main p {
    margin-bottom: 10px;
    word-wrap: break-word;
    line-height: 24px;
    max-height: 48px;
    overflow: hidden;
}

.ccInfo .main p {
    margin-bottom: 10px;
    word-wrap: break-word;
    line-height: 24px;
    max-height: 48px;
    overflow: hidden;
}
.ccInfo .main h3 {
    left: 540px;
    bottom: 20px;
    line-height: 1;
    font-size: 28px;
    color: #d32f24;
    font-weight: normal;
    position: absolute;
}
</style>

效果