Скачать или смотреть How to Dynamically Retrieve the id From a List in Flutter

Discover how to dynamically get the `id` from your list in Flutter and navigate between pages. Learn how to use `GridView.builder` effectively to pass data!
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This video is based on the question https://stackoverflow.com/q/72505079/ asked by the user 'Giovanni' ( https://stackoverflow.com/u/11069440/ ) and on the answer https://stackoverflow.com/a/72505436/ provided by the user 'Babul' ( https://stackoverflow.com/u/4353594/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction: Navigating with Dynamic IDs in Flutter

When developing an app with Flutter, you may encounter situations where you need to pass data (like an id) from one page to another. This is especially common when dealing with lists—such as a CardView containing various categories in a grid format. In this guide, we’ll address the challenge of dynamically retrieving the id from a list and passing it to a new page when an item is clicked.

Understanding the Problem

In the example given, there's a DUMMY_CATEGORIES list that holds category objects, each containing a name and an id. The goal is to tap on a category within a GridView and navigate to a new page, carrying the id of the tapped category.

Here’s a quick recap of the relevant components in the code:

DUMMY_CATEGORIES: Holds the categories' data.

HomePage: Displays categories in a grid format using GridView.

The challenge lies in how to capture the correct id associated with a category when the user interacts with it.

Solution Overview: Using GridView.builder

A great way to address this issue is by utilizing the GridView.builder widget instead of the standard GridView. This approach allows for dynamic item creation and provides easy access to tap actions for each item.

Implementing GridView.builder

Step 1: Use GridView.builder

Here’s how you can implement the GridView.builder in your HomePage widget:

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

Breakdown of the Code:

GridView.builder: This sets up the grid with dynamic content.

itemCount: Measures how many items you have (duration of DUMMY_CATEGORIES).

itemBuilder: This function defines how to create each grid item.

InkWell: A material design ripple effect that allows for tap actions.

Step 2: Create the NewScreen

Next, you'll want to set up the NewScreen class, which will receive the id you passed from the previous screen:

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

Explanation of the NewScreen:

NewScreen: A simple StatelessWidget that takes the received id as a constructor argument.

AppBar: Displays the title showing which category ID was selected.

body: Contains a centered text widget to confirm which id was passed.

Conclusion

By leveraging GridView.builder, you can easily handle dynamic content in Flutter and enable navigation while passing necessary data like an id. This technique not only enhances interactivity in your app but also provides a seamless user experience.

Next time you need to pass data between pages in your Flutter application, remember this approach for simplicity and effectiveness! Feel free to share your comments or questions below. Happy coding!