完善了数据同步功能

model/class.js

@@ -9,10 +9,10 @@ class Class extends AV.Object{
     this.set("name", value);
   }
   get students(){
-    return this.get("students");
+    
   }
   add_student(user){
-    this.addUnique("students", user.id);
+    
   }
   del_student(user){
     let students = this.get("students");
@@ -20,23 +20,19 @@ class Class extends AV.Object{
       this.remove(user.id);
     }
   }
-  static all() {
-    var query = new AV.Query("Class_");
-    return query.find();
-  }
   enter() {
     this.leave();
     this._presence = new Presence({
       user: AV.User.current(),
       class: this
     });
-    this._presence.save();
+    this._presence.save(); 
   }
   leave() {
     if (this._presence != null) {
       this._presence.destroy();
     }
-  }
+  } 
   present_students() {
     var query = new AV.Query("Presence");
     //query.equalTo("class", this._class.id);

pages/classroom/classroom.js

@@ -1,55 +1,115 @@
 // 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: [],
-  present_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
-    present_students: [], // 出席的学生的用户名即上文提及的student.username
-    students: [],  // 该课程所有的学生
-    unpresent_students: [], //没有出席的学生的用户名，不建议使用该数据，考虑弃用
+    //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）
   },
-  fetch_present: function(){
+
+  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 = AV.Object.createWithoutData("Class_", options.class_id);
-    this.class.fetch().then((class_)=>{
-      console.log(this.class);
-      this.setData(this.class.get("name"));
-    })
+    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 () {
-    this.fetch_present().then((presents)=>{
-      console.log({students: presents.map((present)=>{return present.get("user")})});
-      this.setData(jsonify({students: presents.map((present)=>{return present.get("user")})}));
-    })
     console.log("onReady");
   },
 
@@ -58,6 +118,7 @@ Page({
    */
   onShow: function () {
     console.log("onShow");
+    console.log("enter class when onShow");
     this.class.enter();
   },
 
@@ -75,13 +136,14 @@ Page({
   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)();
   },
 
   /**

pages/classroom/classroom.json

@@ -1,3 +1,4 @@
 {
-  "usingComponents": {}
+  "usingComponents": {},
+  "enablePullDownRefresh": true
 }