How to Store a Json Object in SharedPreferences with Flutter

Learn how to effectively store and retrieve JSON objects in SharedPreferences using Flutter with step-by-step guidance.
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This video is based on the question https://stackoverflow.com/q/71805974/ asked by the user 'Mustafizur Rahman' ( https://stackoverflow.com/u/18269269/ ) and on the answer https://stackoverflow.com/a/71806192/ provided by the user 'Dani3le_' ( https://stackoverflow.com/u/11442598/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Store a Json Object in SharedPreferences with Flutter

Storing data locally on a user's device is crucial for many applications, especially when you want to keep a user's session active or save user's settings. In Flutter, one of the most common ways to achieve this is by using the SharedPreferences package. In this guide, we'll tackle the specific question: How can we store a JSON object in SharedPreferences in Flutter?

Understanding the Problem

You may often find yourself needing to save a user's login information returned from an API in a JSON format. However, SharedPreferences only accepts strings as its data type. Therefore, it's essential to encode the JSON object into a string before storing it and decode it back into a JSON object when retrieving it.

Example Scenario

Let’s say you've just logged in a user, and you've received a JSON response containing a user token and other information. Below is an example of a response you might receive:

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You want to save this JSON data locally using SharedPreferences.

Solution: Storing JSON in SharedPreferences

1. Encoding JSON to String

To store the JSON object, you need to convert it into a string format using jsonEncode. Here's how you can save the data after a successful login:

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2. Decoding String back to JSON

When you need to retrieve the data, you can get the string associated with the key and convert it back into a JSON object using jsonDecode. Here's how:

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3. Full Implementation Example

Here’s how you can tie everything together into your login method:

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Key Takeaways

SharedPreferences can only store strings, so always encode your JSON object before saving it.

When retrieving data, ensure you decode it back into a format you can work with.

Use jsonEncode to convert JSON objects to strings and jsonDecode to convert strings back to JSON objects.

Conclusion

Working with JSON data in Flutter via SharedPreferences is straightforward once you understand the encoding and decoding process. By leveraging this knowledge, you can efficiently manage user sessions and preferences in your Flutter applications, providing a seamless user experience.

Now that you understand how to store Json objects in SharedPreferences, it's time to apply this knowledge in your own Flutter projects!