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Discover how to identify file types by extracting extensions from Base64 strings in Flutter and Dart with a simple function.
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How to Easily Get File Extensions from Base64 Strings in Flutter | Dart

When working with files in a Flutter application, you might come across a situation where you receive a base64 string from an API. Understanding the file type encapsulated in that string is essential, especially if you want to display different files appropriately—like images or documents. In this guide, we'll explore how to identify the file extension from a base64 string in Flutter effectively.

The Problem

Imagine receiving a base64 string of a document from an API.

You may need to determine which format the string represents. For example:

If it’s an image (like jpg, jpeg, or png), you would want to display it in an image widget.

If it’s a PDF, you might want to use a PdfView widget.

Thus, knowing how to extract the file extension from a base64 string becomes crucial. So, how can you achieve this in Dart and Flutter? Let’s dive into the solution!

Solution: Identifying File Extensions

The Approach

You can determine the file type by checking the first character of your base64 string. Each different file type corresponds to a specific character as follows:

/: JPEG

i: PNG

R: GIF

U: WebP

J: PDF

Implementing the Solution

To make this process easier, you can create a simple function that checks the first character and returns the appropriate extension. Below is a code snippet you can use in your Flutter application:

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

How to Use the Function

Pass the Base64 String: Simply call the getBase64FileExtension function, passing the base64 string as an argument.

Handle the Output: Store the returned string (the file extension) and use it to decide how to display your content.

Example Usage

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

Conclusion

Identifying the file extension from a base64 string in Flutter is straightforward with the function we’ve explored. By checking the initial character of the base64 string, you can efficiently determine the file type, enabling you to display the content accurately. This small step can significantly enhance the user experience in your Flutter applications.

Feel free to adapt and use the function we've provided to meet your requirements!