How to Retrieve File Contents from ipfs-http-client in JavaScript

Learn how to effectively use the `cat` method in `ipfs-http-client` to fetch and decode files from IPFS. Step-by-step guide included.
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How to Retrieve File Contents from ipfs-http-client in JavaScript

If you're working with InterPlanetary File System (IPFS) and need to retrieve file contents using ipfs-http-client, you might encounter challenges when trying to decode the returned data. This guide will guide you through the process of fetching a file stored on IPFS using the cat functionality, as well as how to decode its contents into usable formats such as strings or JSON.

Understanding the Problem

When you use ipfs-http-client to read files from IPFS, you typically want to fetch data in a readable format. If you've ever seen an array of binaries in your console log instead of the actual content, you're not alone! This happens because the data is returned in a Uint8Array format. The key to resolving this issue lies in correctly decoding that array into the format you need.

Step-by-Step Solution

Let’s break down the process into clear steps to make it easy for you to follow.

Step 1: Create Your IPFS Client

You first need to set up the ipfs-http-client to interact with your IPFS node. Here’s a sample code snippet that demonstrates how to create a client connected to Infura:

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

You need to replace ipfsUrl() and ipfsAuthPhrase() with the appropriate configurations for your Infura project.

Step 2: Format Your CID

The Content Identifier (CID) is used to point to the file you want to fetch. Ensure your CID is in the correct format:

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

Step 3: Fetch the File Using cat

You can now retrieve the file contents using the cat method. This returns a stream of data:

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

Step 4: Decode the Content

Now that you have your content as an array of binaries, you'll need to decode it based on the type of data you're expecting.

If the content is JSON:

To decode JSON data, create a buffer from the content array and convert it to a string in UTF-8 format before parsing it as JSON:

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

If the content is an image:

If you’re fetching an image, you may want to convert it to a base64 string. Use the following code to do so:

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

Conclusion

By following the steps outlined above, you can effectively retrieve and decode file contents from IPFS using ipfs-http-client. Whether you're working with JSON data or images, decoding is straightforward once you understand how to manipulate the Uint8Array returned by the client.

If you have any further questions or need more assistance with IPFS, feel free to leave a comment below.