Debugging null reference exceptions in MvvmCross can be challenging, but there are several tools and strategies that can help. Here are some detailed approaches:
Debugging Tools and Strategies
1. Visual Studio Exception Settings**
To effectively debug null reference exceptions, it's crucial to configure Visual Studio to break on all Common Language Runtime (CLR) exceptions. This can be done by going to Debug > Windows > Exception Settings and checking the box next to Common Language Runtime Exceptions. This will allow you to step through the code at the point where the exception is raised, providing valuable insights into what might be causing the null reference[3].2. Source Linking**
MvvmCross supports source linking, which allows you to step through the MvvmCross source code directly from your project. This is particularly useful for understanding how MvvmCross handles certain operations internally. To enable source linking, go to Tools > Options > Debugging > General and tick Enable source server support**[7].3. MvvmCross Playground Sample**
If you're experiencing issues that you can't reproduce in a simple test case, try using the MvvmCross Playground sample app. This sample is included with the MvvmCross source code and can help you isolate the problem by reproducing it in a controlled environment[3].4. Community Support**
The MvvmCross community is active and helpful. If you're stuck, consider asking for assistance on platforms like Stack Overflow or the MvvmCross Slack channel. Additionally, you can raise an issue on the MvvmCross GitHub page if you believe you've found a bug[3].5. Workarounds for Specific Issues**
For issues like null references when using `MvxAsyncCommand`, ensure that `Mvx.IoCProvider` is properly initialized. This can often be resolved by manually setting up the IoC provider in your unit tests[1].6. MvvmCross Plugins**
While plugins themselves might not directly help with debugging null references, they can simplify certain functionalities and reduce the complexity of your codebase, potentially making it easier to identify and fix issues. Ensure that any plugins you use are correctly initialized and referenced in your project[9].7. Code Review and Testing**
Finally, thorough code reviews and unit testing can help catch null reference exceptions early. Ensure that all dependencies are properly injected and that your view models are correctly set up before attempting to use them.By combining these strategies, you can more effectively debug and resolve null reference exceptions in your MvvmCross applications.
Citations:[1] https://stackoverflow.com/questions/53597908/mvvm-cross-null-references-when-unit-testing-mxvasynccommand/53618570
[2] https://www.mvvmcross.com/documentation/plugins/3rd-party-plugins
[3] https://nicksnettravels.builttoroam.com/post-2018-07-31-debugging-and-contributing-to-mvvmcross-aspx/
[4] https://stackoverflow.com/questions/18954938/nullreference-exception-during-binding-with-mvvmcross
[5] https://www.mvvmcross.com/documentation/getting-started/mvvmcross-packages
[6] https://github.com/MvvmCross/MvvmCross/issues/4286
[7] https://www.mvvmcross.com/documentation/contributing/debugging-with-symbols
[8] https://www.nuget.org/packages/MvvmCross.Plugin.BLE/
[9] https://www.mvvmcross.com/documentation/plugins/getting-started