使用 Meteor 和 blaze 在掌上电脑上正确加载数据

Question

我通过插件 awsp:handsontable@0.16.1 在 Meteor 1.4.1 上使用 handsontable

我遇到的问题是每次更改值时都会重新渲染矩阵，这会产生两个问题。首先是编辑单元格的焦点丢失，滚动回到顶部。第二个是有时值没有保存，因为每次更改都会重新加载矩阵的数据。

我订阅数据和渲染表格的方式如下：

Template.connectivityMatrix.onCreated(function () {
  this.activeScenario = () => Session.get('active_scenario');

  this.autorun(() => {
    this.subscribe('connectivityMatrixUser', this.activeScenario());
  });
});

Template.connectivityMatrix.onRendered(function () {
  this.autorun(() => {
    if (this.subscriptionsReady()) {
      const activeScenario = Session.get('active_scenario');
      const currentScenario = Scenarios.findOne({_id: activeScenario});
      const currentTurn = currentScenario.turn;
      const numObj = ConnectivityMatrix.find({scenario_id: activeScenario, user_id: Meteor.userId(), turn: currentTurn}).count();

      var myData = [];  // Need this to create instance
      var container = document.getElementById('connectivity-matrix');

      var hot = new Handsontable(container, { // Create Handsontable instance
        data: myData,
        startRows: numObj,
        startCols: numObj,
        afterChange: function (change, source) {  // 'change' is an array of arrays.
          if (source !== 'loadData') {  // Don't need to run this when data is loaded
            for (i = 0; i < change.length; i++) {   // For each change, get the change info and update the record
              var rowNum = change[i][0]; // Which row it appears on Handsontable
              var row = myData[rowNum];  // Now we have the whole row of data, including _id
              var key = change[i][1];  // Handsontable docs calls this 'prop'
              var oldVal = change[i][2];
              var newVal = change[i][3];
              var setModifier = {$set: {}};   // Need to build $set object
              setModifier.$set[key] = newVal; // So that we can assign 'key' dynamically using bracket notation of JavaScript object
              ConnectivityMatrix.update(row._id, setModifier);
            }
          }
        }
      });

      myData = ConnectivityMatrix.find({scenario_id: activeScenario, turn: currentTurn, user_id: Meteor.userId()}, {sort: {created_at: 1}}).fetch();  // Tie in our data
      hot.loadData(myData);
    }
  });
});

我想要实现的是只创建一次矩阵，而不是在每次数据更改时重新创建它，以便保持焦点并始终保存数据。 因此，我尝试按照 question 中的建议仅在 this.autorun() 的块中保留最后两行@

Template.connectivityMatrix.onRendered(function () {
  const activeScenario = Session.get('active_scenario');
  const currentScenario = Scenarios.findOne({_id: activeScenario});
  const currentTurn = currentScenario.turn;
  const numObj = ConnectivityMatrix.find({scenario_id: activeScenario, user_id: Meteor.userId(), turn: currentTurn}).count();

  var hot = new Handsontable(container, { // Create Handsontable instance
    ...
  });

  this.autorun(() => {
    if (this.subscriptionsReady()) {
      myData = ConnectivityMatrix.find({scenario_id: activeScenario, turn: currentTurn, user_id: Meteor.userId()}, {sort: {created_at: 1}}).fetch();  // Tie in our data
      hot.loadData(myData);
    }
  });
});

但是当我第一次加载页面时，数据不可用所以我收到错误

无法读取未定义的属性“转”

因此，如何正确获取创建表格所需的所有数据，而无需在单元格值更改时重新渲染它？

提前感谢您的帮助。

Answer 1

您正在尝试在 Scenarios 和 ConnectivityMatrix 集合准备好之前对其进行查询。将所有 mongo 查询移到 this.subscriptionsReady() 条件块中。

Answer 2

我设法做我需要的方法是在矩阵被渲染后停止计算。代码如下：

Template.connectivityMatrix.onRendered(function () {    
  this.autorun((computation) => {
    if (this.subscriptionsReady()) {    
      const currentScenario = Scenarios.findOne({_id: activeScenario});
      const currentTurn = currentScenario.turn;
      const numObj = ConnectivityMatrix.find({scenario_id: activeScenario, user_id: Meteor.userId(), turn: currentTurn}).count();

      var myData = [];  // Need this to create instance
      var container = document.getElementById('connectivity-matrix');

      var hot = new Handsontable(container, { // Create Handsontable instance
        data: myData,
        colHeaders: arrayRowsCols,
        rowHeaders: arrayRowsCols,
        height: '450',
        maxRows: numObj,
        maxCols: numObj,
        columns: columns,
        afterChange: function (change, source) {  // 'change' is an array of arrays.
          if (source !== 'loadData') {  // Don't need to run this when data is loaded
            for (i = 0; i < change.length; i++) {   // For each change, get the change info and update the record
              var rowNum = change[i][0]; // Which row it appears on Handsontable
              var row = myData[rowNum];  // Now we have the whole row of data, including _id
              var key = change[i][1];  // Handsontable docs calls this 'prop'
              var oldVal = change[i][2];
              var newVal = change[i][3];
              var setModifier = {$set: {}};   // Need to build $set object
              setModifier.$set[key] = newVal; // So that we can assign 'key' dynamically using bracket notation of JavaScript object
              ConnectivityMatrix.update(row._id, setModifier);
            }
          }
        }
      });

      myData = ConnectivityMatrix.find({scenario_id: activeScenario, turn: currentTurn, user_id: Meteor.userId()}, {sort: {created_at: 1}}).fetch();  // Tie in our data
      hot.loadData(myData);
      computation.stop();
    }
  });
});