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Discover the best practices for calling asynchronous methods in Flutter to ensure optimal performance and user experience.
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How to Efficiently Load Data in Flutter Without Overloading Service Calls

When developing applications, particularly in Flutter, a common challenge arises when attempting to fetch data from a server. This is especially relevant when creating features like an "endless" list of recommended items as viewed by users. While you want to keep your application responsive and functional, it becomes crucial to avoid excessive service calls that can degrade performance and user experience.

The Problem at Hand

Imagine you want to display a list of recommended items to users based on their interaction with the application. To achieve this, you've implemented an asynchronous method, getItemsFromServer(...), which fetches 100 new items from the server. However, this process can be costly in terms of server usage, application performance, and user device battery life.

The challenge arises when you attempt to call this function naively with a simple condition:

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While this approach seems straightforward, it leads to a significant problem: if the user views or clicks on items, this method could potentially be invoked multiple times—up to 20 times—before your application has a chance to finish the first call.

The Need for an Efficient Solution

Your goal is to ensure that getItemsFromServer(...) is called only when required, specifically when there are less than 20 items that the user hasn't viewed yet, all while maintaining a smooth user experience.

Solution Overview

The best way to address this issue is to manage the call to the asynchronous method using a Future object. This allows you to track whether the fetch operation is already in progress and prevents duplicate calls while waiting for the response.

Implementation Steps

Here is an effective way to implement this in your Flutter application:

Declare a Future Variable: Use a Future variable to track the state of an ongoing data fetch.

Control Access with a Conditional Check: Before calling the fetch method, check if the variable is null and if the number of items is below your threshold (e.g., 20).

Handle the Asynchronous Operation: After making the call, await its completion, then reset the variable. This ensures that subsequent interactions don’t trigger another call until the current one completes.

Here is a practical code snippet demonstrating this approach:

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

Explanation of the Code

Future Variable: The itemsBeingGotten variable tracks whether a fetch operation is currently in progress.

Conditional Logic: The if statement checks both conditions—if there’s no current operation and if the items not viewed are less than 20.

Async Call: If the conditions are met, it assigns the getItemsFromServer() call to itemsBeingGotten and awaits its completion before resetting the variable to allow future calls when necessary.

Conclusion

By efficiently managing your asynchronous method calls, you can significantly improve the responsiveness of your Flutter application while reducing unnecessary server load. This approach not only enhances performance but also elevates the overall user experience by ensuring that users have a smooth interaction with your application without interruptions.

Implementing a strategy to track ongoing operations using a Future object is a foundational practice in building efficient applications, especially when dealing with data fetching mechanisms.

By following these guidelines, you can create a robust solution that effectively manages service calls in your Flutter projects.