Скачать или смотреть How to Append a Blob File in Azure Blob Storage Using NodeJS

Learn how to efficiently `append data` to a JSON blob file in Azure Blob Storage using the @ azure/storage-blob SDK in NodeJS.
---
This video is based on the question https://stackoverflow.com/q/70639321/ asked by the user 'Krishna Ecrio' ( https://stackoverflow.com/u/17731111/ ) and on the answer https://stackoverflow.com/a/70639425/ provided by the user 'Gaurav Mantri' ( https://stackoverflow.com/u/188096/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How do I append a blob file using @ azure/storage-blob sdk ? (NodeJS)

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Append a Blob File in Azure Blob Storage Using NodeJS

Appending data to a blob in Azure Blob Storage might seem straightforward at first glance, but it requires a deeper understanding of how blob storage works. In this guide, we'll tackle a common issue faced when trying to append data to a JSON blob and provide a clear solution to help you achieve your goal.

The Problem

Suppose you have a JSON file called mainfile.json stored in Azure Blob Storage. This file contains an array of objects, and you want to append a new object to this array. Here’s the current state of the file:

[[See Video to Reveal this Text or Code Snippet]]

You wish to append this new data:

[[See Video to Reveal this Text or Code Snippet]]

The desired output for mainfile.json after appending should be:

[[See Video to Reveal this Text or Code Snippet]]

You are using the @ azure/storage-blob SDK, and your code to handle this looks like this:

[[See Video to Reveal this Text or Code Snippet]]

However, the output is not what you expected, and it reveals a misunderstanding of how Blob Storage handles data.

Understanding Azure Blob Storage

Before diving into the solution, it's essential to grasp how Azure Blob Storage operates:

Blob Storage treats all entries as a sequence of bytes without understanding the structure (like JSON).

It cannot automatically parse and manage data formats like JSON. This means the SDK cannot recognize that you intend to append an item to a JSON array.

The Solution

To successfully append a new piece of JSON data to your existing blob, we will follow these steps:

Step 1: Download the Blob Content

First, read the existing blob content into a string. You will need to utilize the SDK to download the current blob and convert it to a string format.

Step 2: Parse and Modify the JSON

Use JSON.parse to convert the string into a JavaScript array object. Add your new data object to this array.

Step 3: Upload the Updated JSON

Once the new object is appended, convert the array back to a string format using JSON.stringify, and upload it back to the blob storage, overwriting the original data.

The Code Implementation

Here's how the updated code will look:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Appending data to a blob in Azure Blob Storage requires you to handle the JSON structure yourself, using the parsing and stringifying methods of JavaScript. By downloading the blob, modifying the content with JSON.parse and JSON.stringify, and re-uploading it, you can effectively expand your JSON object.

Implement this approach in your project, and you’ll be able to append data to your blobs successfully!