无法从下载的Blob中读取readyStreamBody

问题描述

我可以检查内部缓冲区以查看是否存在我的文本数据吗?我在正确使用node.js的Stream.read()吗?

I can I check the internal buffer to see if my text data is present? Am I using node.js' Stream.read() correctly?

我有一个文本文件作为blob存储在azure存储中.当我下载Blob时，我得到了可读的流以及有关Blob的信息.返回数据的contentLength为11，这是正确的.

I have a text file as a blob stored on azure-storage. When I download the blob I get readable stream as well as info about the blob. The return data has a contentLength of 11 which is correct.

我看不懂蒸汽.它始终返回null. node.js文档说，

I am unable to read the steam. It always returns null. The node.js docs say,

根据Node.js，没有可用数据.

According to Node.js there is no data available.

async function downloadData(){
    const textfile = "name.txt"

    const containerURL = ContainerURL.fromServiceURL(serviceURL, "batches")
    const blockBlobURL = BlockBlobURL.fromContainerURL(containerURL, textfile );
    let baseLineImage = await blockBlobURL.download(aborter, 0)

    console.log(baseLineImage.readableStreamBody.read())
    return

}

方法blobBlobURL.download下载数据.更特定于Azure it，

The method blobBlobURL.download downloads the data. More specific to Azure it,

在Node.js中，数据以Readable流readStreamStreamBody返回在浏览器中，数据以promise blobBody的形式返回

In Node.js, data returns in a Readable stream readableStreamBodyIn browsers, data returns in a promise blobBody

推荐答案

根据您的代码，我看到您正在使用适用于JavaScript的Azure存储SDK V10 .

According to your code, I see you were using Azure Storage SDK V10 for JavaScript.

在此软件包 @azure/storage-blob 的npm页面中，是示例代码中名为streamToString的异步函数，可以帮助您从可读流中读取内容，如下所示.

In the npm page of this package @azure/storage-blob, there is an async function named streamToString in the sample code which can help you to read the content from readable stream, as below.

// A helper method used to read a Node.js readable stream into string
async function streamToString(readableStream) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    readableStream.on("data", data => {
      chunks.push(data.toString());
    });
    readableStream.on("end", () => {
      resolve(chunks.join(""));
    });
    readableStream.on("error", reject);
  });
}

然后，您的代码将如下所示编写.

Then, your code will be writen like below.

async function downloadData(){
    const textfile = "name.txt"

    const containerURL = ContainerURL.fromServiceURL(serviceURL, "batches");
    const blockBlobURL = BlockBlobURL.fromContainerURL(containerURL, textfile );
    let baseLineImage = await blockBlobURL.download(aborter, 0);

    let content = await streamToString(baseLineImage.readableStreamBody);
    console.log(content)
    return content
}

希望有帮助.

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