FileReader 未使用 AngularJS 正确加载文件 [英] FileReader not loading file properly using AngularJS

问题描述

我正在尝试将一个 csv 文件加载到 AngularJS 中，以便我可以对内容进行一些操作.它并不像我想要的那样工作.为了测试它是否正确加载，我将其加载到文本区域以查看内容.

当我加载文件时，它说它已正确加载，但 onload() 事件在我加载第二个 CSV 文件之前似乎不会触发，在这种情况下，第一个文件显示在文本区域中.

HTML:

<输入 ng-model="csv"onchange="angular.element(this).scope().fileChanged()"type="file" accept=".csv" id="fileInput"/>
<br/><div><textarea ng-model="csvFile" readonly="true" style="width:99%; height:500px" disabled></textarea>

JS:

$scope.fileChanged = function() {$scope.$apply(function() {var csvFileInput = document.getElementById('fileInput');var reader = new FileReader();var csvFile = csvFileInput.files[0];reader.onload = function(e) {$scope.csvFile = reader.result;};reader.readAsText(csvFile);});};

当我将其放入 JSFiddle 时，该文件根本不会出现在文本区域中.我是 JSFiddle 的新手，所以我不知道为什么会这样.

任何帮助都将不胜感激.

解决方案

重新排列一些代码行，希望注释足够解释

$scope.fileChanged = function() {//定义读者var reader = new FileReader();//加载事件的处理程序(只是定义它，现在不执行它)reader.onload = function(e) {$scope.$apply(function() {$scope.csvFile = reader.result;});};//获取<输入>元素和选定的文件var csvFileInput = document.getElementById('fileInput');var csvFile = csvFileInput.files[0];//使用 reader 读取选中的文件//当读操作成功完成时，加载事件被触发//并由我们的 reader.onload 函数处理reader.readAsText(csvFile);};

参考:MDN 上的 FileReader

I'm trying to load a csv file into AngularJS so I can do some manipulation on the contents. It is not quite working as I want it to. To test if it is loading properly, I am loading it into a textarea to view the contents.

When I load the file, it says it is loaded properly but the onload() event doesn't seem to be firing until I load a second CSV file, in which case the FIRST file is displayed in the textarea.

HTML:

<div>
  <input ng-model="csv"
            onchange="angular.element(this).scope().fileChanged()"
            type="file" accept=".csv" id="fileInput"/>
</div>
<br/>
<div>
  <textarea ng-model="csvFile" readonly="true" style="width:99%; height:500px" disabled></textarea>
</div>

JS:

$scope.fileChanged = function() {

  $scope.$apply(function() {
      var csvFileInput = document.getElementById('fileInput');
      var reader = new FileReader();
      var csvFile = csvFileInput.files[0];
      reader.onload = function(e) {
          $scope.csvFile = reader.result;
      };
      reader.readAsText(csvFile);
  });
};

And when I put this into JSFiddle, the file doesn't appear in the textarea at all. I'm new with JSFiddle so I don't know why that is happening.

Any help at all would be appreciated.

解决方案

Reordering some lines of your code, hope the comments are explanatory enough

$scope.fileChanged = function() {

  // define reader
  var reader = new FileReader();

  // A handler for the load event (just defining it, not executing it right now)
  reader.onload = function(e) {
      $scope.$apply(function() {
          $scope.csvFile = reader.result;
      });
  };

  // get <input> element and the selected file 
  var csvFileInput = document.getElementById('fileInput');    
  var csvFile = csvFileInput.files[0];

  // use reader to read the selected file
  // when read operation is successfully finished the load event is triggered
  // and handled by our reader.onload function
  reader.readAsText(csvFile);
};

Reference: FileReader at MDN

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