意见:如何从“内部"设置数据?功能?

问题描述

我正在使用Vue和Axios显示进度条. uploadProgress 是我的Vue实例中的数据键.当我尝试使用内部函数进行设置时，它只是说其未定义.这是我的代码的简化版本:

I'm using Vue and Axios to display a progress bar. uploadProgress is a data key in my Vue instance. When I try to set it using an inner function, it just says its undefined. Here's a simplified version of my code:

someVueMethod() {
  this.uploadProgress = 0 // this works

  let config = { 
    onUploadProgress(progress) {
      // this doesn't work, error says uploadProgress is undefined
      this.uploadProgress += progress.loaded / progress.total
    }
  }
  axios.put(url, file, config).then(res => {
    // handle the response
  })
}

如何从该内部函数中设置 uploadProgress ?

How can I set uploadProgress from within that inner function?

推荐答案

您已将 uploadProgress 添加到函数 someVueMethod 的上下文中，但尝试在其中访问函数 onUploadProgress 的上下文.您需要使用这样的原始上下文.

You have added uploadProgress to the context of the function someVueMethod, but are trying to access it in the context of the function onUploadProgress. You need to use the original context like this.

someVueMethod() {
  var self = this; //store the context of someVueMethod
  this.uploadProgress = 0 // this works

  let config = { 
    onUploadProgress(progress) {
      // use the original context using self
      self.uploadProgress += progress.loaded / progress.total
    }
  }
  axios.put(url, file, config).then(res => {
    // handle the response
  })
}

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