Скачать или смотреть How to Dynamically Add Rows to a Column in Flutter

Discover how to dynamically add rows to a column in Flutter without errors. This step-by-step guide will help you understand widget immutability and dynamic list creation in Dart.
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This video is based on the question https://stackoverflow.com/q/78075540/ asked by the user 'Güven Acar' ( https://stackoverflow.com/u/4207853/ ) and on the answer https://stackoverflow.com/a/78075779/ provided by the user 'Su Mit' ( https://stackoverflow.com/u/18523016/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Dynamically Add Rows to a Column in Flutter: A Beginner's Guide

If you are new to Flutter and just starting to explore its rich user interface capabilities, you might find yourself in a situation where you want to dynamically add rows to a column. This task can be a bit tricky, especially when dealing with Flutter's widget immutability.

In this guide, we are going to address a common problem faced by new Flutter developers: how to properly add dynamic rows to a dynamic column without encountering an UnsupportedError.

The Problem: Understanding Widget Immutability

To illustrate the problem, here's the code you may have started with:

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

When you try to run this code, an error will pop up:

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

Why Does This Error Occur?

In Flutter, widgets are immutable, which means their properties (like children) can't be changed after they've been created. When you attempt to add rows to a column using .children.add(), you're trying to modify a property of an immutable widget, which leads to the UnsupportedError.

The Solution: Building a List of Widgets Dynamically

To dynamically add rows to a column without encountering such errors, you'll need to build your widget list in a different way. Here's how you can do that:

Step-by-Step Implementation

Define Your Rows Dynamically: Instead of trying to modify the Column directly, define your rows within a list.

Use the List.generate Method: This method will allow you to create the list of rows dynamically.

Here's an improved version of your code:

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

Key Changes Made

Removed Immutable Widgets: Instead of trying to reuse an immutable Row, we generate new Row widgets each time in a loop inside the List.generate() method.

Dynamic List Creation: The List.generate() method creates a list of Row widgets, which allows us to have as many rows as needed without modifying an immutable column.

Conclusion

Adding dynamic rows to a column in Flutter can be challenging if you're unaware of the immutability of widgets. By embracing a list-generating approach, you can create a responsive UI that adjusts to various states without throwing errors.

Now that you have a grasp of how to dynamically add rows to columns, you can expand your Flutter app's capability with confidence. If you have any further questions or need additional guidance on Flutter, feel free to reach out!