Resolving null Values in TextField and DatePicker in Flutter Todo App

Описание: Learn how to prevent `null` values in your Flutter Todo app by properly managing TextField and DatePicker inputs.
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This video is based on the question https://stackoverflow.com/q/65928317/ asked by the user 'elios_cama' ( https://stackoverflow.com/u/14163640/ ) and on the answer https://stackoverflow.com/a/65932336/ provided by the user 'Bach' ( https://stackoverflow.com/u/10488444/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting null Values in Your Flutter Todo App

Developing a Todo application can be a rewarding experience as you get to incorporate features like task creation with deadlines. However, you may encounter issues, particularly when inputs are not being captured as expected. If you find that your TextField and DatePicker in Flutter return null values when you click the "Add" button, you're not alone!

In this guide, we will diagnose the problem and provide you with an effective solution to ensure your application captures and retains user input correctly.

The Problem: Unexpected null Values

In a typical scenario, your Add Screen will feature a TextField for users to input the task title and a DatePicker for selecting a task deadline. However, when you click the "Add" button, it may create a task with an empty title and date. This is commonly due to improper value handling in the code.

Code Snippet Overview

Here's the problematic part of your code that causes the null values:

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As you can see, the input values used to create a new task (newTaskTitle and formatedDate) are not being appropriately retained when you navigate away from the Add Screen.

The Solution: Implementing TextEditingController and Async Handling

To properly manage user inputs, we need to employ TextEditingController for the TextField, and modify the way we handle date selection with the DatePicker. Below is a step-by-step breakdown of the solution.

Step 1: Use TextEditingController

The TextEditingController assists in managing the state of your TextField. Let's create an instance of it:

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Step 2: Update TextField to Utilize the Controller

Modify your TextField in the build method to utilize the _textController, ensuring that it captures user input:

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Step 3: Return the Date from the DatePicker

Make sure your date selection returns the selected date properly. Here’s how you can do this with an Async Function:

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In the callback when the "OK" button is pressed, use your formatted date directly.

Step 4: Finalize the Add Button Logic

Now that we have our inputs correctly set, we can finalize the Add button logic, capturing both the task title and chosen date accurately:

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Implementing a Complete Solution

Overall, here’s how your revised AddScreen would look:

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Wrap Up

By utilizing TextEditingController and properly handling the DatePicker, you can effectively eliminate the issue of null values in your Flutter Todo app. Implement these strategies to enhance the robustness of your application, providing a seamless experience for users.

Feel free to share any further challenges or questions you may have while developing your Flutter app in the comments below!