Solving the getParam is not a function Error in React Navigation Header

Learn how to resolve the `TypeError: navigation.getParam is not a function` issue in your React Native app by effectively using onLogout functions in headers.
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This video is based on the question https://stackoverflow.com/q/73342419/ asked by the user 'Youssef' ( https://stackoverflow.com/u/11833845/ ) and on the answer https://stackoverflow.com/a/73343069/ provided by the user 'Essadrati' ( https://stackoverflow.com/u/15824823/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving the getParam is not a function Error in React Navigation Header

React Navigation is an essential library for navigating between screens in React Native applications. While it offers powerful features, developers may encounter common issues, such as the "TypeError: navigation.getParam is not a function" error. In this post, we will dissect a specific case of this error and provide a clear solution.

The Problem: Understanding the Error

In this scenario, a developer attempts to implement a logout functionality in a header icon situated within a tab navigator. The goal is to make the icon trigger a function called onLogout defined in a separate file. However, when they try to access the function via navigation.getParam, the application throws an error indicating that this method does not exist.

Code Snippet Causing Issues

Here’s a simplified representation of the problematic code:

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

This code fails mainly due to the misunderstanding of how navigation parameters are passed and accessed in the context of React Navigation.

The Solution: Correctly Accessing Parameters

1. Adjust Navigation Options

To fix the error, we need to modify the way we access the navigation parameters. Below is the corrected code snippet:

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

2. Setting Parameters in the Settings Component

Next, ensure that the onLogout function is set as a parameter in the Settings component. You can initialize the parameter in the componentDidMount lifecycle method like this:

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

3. Binding the Function

Do not forget to bind the onLogout function in the constructor before using it:

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

Conclusion: Testing the Implementation

After implementing these adjustments, you should be able to navigate to your Settings screen and see the logout icon. Clicking on it should execute the onLogout function without any errors.

Key Takeaways

Always use props.route.params instead of navigation.getParam to access parameters in function components.

Make sure to set parameters correctly within lifecycle methods.

Ensure all functions are properly bound to avoid context issues.

Implement these solutions in your React Native project, and you should be well on your way to a seamless user experience with functional headers!

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