pk8f3pmu2/pages/classroom/classroom.js

// pages/classroom/classroom.js
const AV = require("../../lib/av-live-query-weapp-min")
const { jsonify } = require('../../utils/leancloudutils');
const bind = require("../../lib/live-query-binding")

Page({
  /**
   页面的初始数据
   students: 该课程所有的学生
    元素student
      student.objectId  该学生的主键，唯一
      student.username 学生的用户名，是唯一，就像微信号一样
      student.name  学生的姓名
   */
  presence: null,
  students: [],
  class: null,
  class_id: null,
  data: {
    //以下数据的同步由该代码文件实现，数据的呈现由classroom.wxml实现
    //命名可能有点混乱......
    present_students: [], 
    // 出席的学生的用户名即上文提及的student.username，考虑弃用，建议替换为presen_stu_ids
    present_stu_ids: [], //出席的学生的主键objectId 
    students: [],  // 该课程所有的学生,  元素类型见上文中的student
    present_stus: [], //出席的学生，元素类型与students中的一样
    unpresent_students: [], //没有出席的学生的用户名，不建议使用该数据，弃用
    class_name: "",//课程名称
    class_id: "",//该课程的主键（编号）
  },

  pull_present: function(){
    var query = new AV.Query("Presence");
    //console.log(this.class);
    query.equalTo("class", this.class);
    query.include("user");
    set_present = this.set_present.bind(this);
    return AV.Promise.all([query.find().then(set_present), query.subscribe()]).then(([presents, subscription])=>{
      this.subscription = subscription;
      if(this.presenceUnbind) this.unbind();
      this.presenceUnbind = bind(subscription, presents, set_present);
    }).catch(error=> console.error(error.message));
  },
  set_present: function(presents){
    //console.log("set_present");
    //console.log(presents);
      var student_ids = presents.map((present)=>{
        user = present.get("user");
        //console.log(user);
        //console.log(typeof user);
        return user.id;
        //return user.get("username");
      });
      //console.log("student_ids:"+student_ids.toString());
      //console.log("students:"+this.students);
      present_stus = this.students.filter(student=> student_ids.indexOf(student.id)>-1)
      //console.log(present_stus);
      present_stu_usernames = present_stus.map(stu => stu.get("username"));
      present_stu_ids = present_stus.map(stu=>stu.id)
      this.setData({
        present_stu_ids: present_stu_ids, 
        present_students: present_stu_usernames});
      this.setData(jsonify({present_stus}));
      return presents;
  },

  fetch_class: function(class_id){
    this.class = AV.Object.createWithoutData("Class_", class_id);
    return this.class.fetch().then((class_) => {
      //console.log(this.class);
      this.setData({
        class_name: this.class.get("name"),
        class_id: this.class.get("objectId")
      });
    }).catch(error=>console.error(error.message))
  },
  fetch_students: function(){
    //console.log("fetch_students");
    var query = new AV.Query("StudentClassMap");
    query.equalTo("class", this.class);
    query.include("user");
    //console.log("fetch_students2")
    return query.find();
  },
  set_students: function(studentClassMaps){
    //console.log("set_students");
    var students = []
    studentClassMaps.forEach((scm, idx, a)=>{
      console.log(a);
      students.push(scm.get("user"));
    });
    this.students = students;
    console.log("this.students");
    console.log(students);
    this.setData(jsonify((students)));
    return students;
  },

  /**
   * 生命周期函数--监听页面加载
   */
  onLoad: function (options) {
    this.class_id = options.class_id;
    //this.class = AV.Object.createWithoutData("Class_", this.class_id);
    this.fetch_class.bind(this)(this.class_id).then(this.fetch_students).then(this.set_students.bind(this)).then(this.pull_present.bind(this));
    console.log("onLoad");
  },

  /**
   * 生命周期函数--监听页面初次渲染完成
   */
  onReady: function () {
    console.log("onReady");
  },

  /**
   * 生命周期函数--监听页面显示
   */
  onShow: function () {
    console.log("onShow");
    console.log("enter class when onShow");
    this.class.enter();
  },

  /**
   * 生命周期函数--监听页面隐藏
   */
  onHide: function () {
    this.class.leave();
    console.log("onHide");
  },

  /**
   * 生命周期函数--监听页面卸载
   */
  onUnload: function () {
    this.class.leave();
    console.log("onUnload");

  },

  /**
   * 页面相关事件处理函数--监听用户下拉动作
   */
  onPullDownRefresh: function () {
      this.pull_present.bind(this)();
  },

  /**
   * 页面上拉触底事件的处理函数
   */
  onReachBottom: function () {

  },

  /**
   * 用户点击右上角分享
   */
  onShareAppMessage: function () {
    console.log("onShareAppMessage");
  }
})