C# WPF Tutorial #24 - Using RelayCommand in MVVM 

Thanks so much! I will be back at it soon, still playing a bit of catch up at work.

@@KampaPlays Nice to hear! :)

yes please

@@KampaPlays Thanks for the videos! I haven't coded in C#/.NET since 2010 and I need to make a tool to work with multiple json files.... Not only has the refresher been good, but a lot has changed since then. I have to build an app that uses 39 json "loot table" files that are all different and create a UI that allows users to edit the files in an understandable manner, then save them again so they can be used by a multiplayer game. Not only do I not have any control over the file format, none of the files contain a complete listing of everything that _can_ exist in them. Since a person can use the tool/app to completely keep an item from spawning in-game (a specifically requested feature) would prevent them from adding it back, one of the tasks I have is figuring out how to combine the "default" files into a master 'database'. I _also_ have to collect the various values of the properties in the files as those could be lost as well. So not only do I need to figure out how to build a single reader that can interpret all the files (that will also hopefully work with future versions of said files), I need to implement a configuration file and a local data file that contains all the possible things, places, and categories (all just different values of 'Name'), rarity values, etc. LOL, then I have to be able to spit it all back out into 39 modified .json files and I don't even know if making structural changes to the files will keep them from working. I know I can add/remove certain levels of child nodes, but the position of those specific child nodes changes from file to file...

@@KampaPlays " You see, in the theory of general relativity soon can be soon or not that soon. It depends" ~anonyme

Thank you!

Thanks so much!

I agree, good and short videos, better than some very long videos

Thanks so much. Hope to continue soon!

@@KampaPlays Lets go!

Yes, absolutely 💯

Thanks so much. I'm thinking (and hoping) that I will have enough time to really get back at it by late spring.

Hopefully soon, very glad to have helped!

Do you mind sharing how did you get the JavaScript job? Networking or online application? Did you have a lot of experience? Have any recommendations for a junior web dev ?

​@@shafialanower3820 I had just graduated from university, so I had no work experience, I simply printed my resume and went to an industrial area and entered an office warehouse of a store that sold PC components, they rejected me immediately because they did not need personnel, However, I was lucky because before I left, the person in charge of the IT area called a friend (my current boss) and asked him if they needed a programmer or something related, he said yes, because a guy had resigned the month previous and they were still not looking for replacement. So I went (their office was across the street) and they hired me right away, they asked me the things I knew, I was honest and told them I know such languages ​​and I have such knowledge, but I am characterized by learning very quickly, and there They hired me. I hope my story is of some use to you xD, actually I also looked at jobs online, but everyone asked me for experience and I didn't have the opportunity to even appear for an interview to try to convince them. Now im just earning experience for a better job.

Thanks so much! Will do.

Thanks so much! I try to do one/week, but lately and for probably a couple more months, work is slowing me down a bit, but I'm still at it!

Thanks so much, I'm hoping to be able to have time to get back to them by late spring.

That's great, thank you!

Thanks so much!!

Thanks so much, will be jumping back in soon!

Thanks so much, I really appreciate it and am glad they have helped!

Thank you!

Thank you. Very glad to help!!

Thanks so much. Hopefully I'll be back at it soon!

Awesome!! Thanks!

Awesome, thanks so much!

Can't wait to see more. Please don't stop publishing and if you have more bring it on the table!!! :-)

Glad to help!

Thank you!!

Thanks so much!!!

Thank you!

Awesome, thank you so much!

Awesome, thank you!

Really appreciate that!!

This is amazing. Thank you for writing, it means a lot. Great job powering through, it will pay off!! It's easy to get overwhelmed in this world, even for people doing it for many years. Just remember that the computer does only what you tell it to do, and take it one line at a time! :) Work(s) have been busy but I will be continuing as soon as I can. I wish you the best; thanks again!

Thanks, glad to help!

Great job getting prepared, I hope your interview goes well! If you think about, let me know how it goes!

Appreciate that! Do you have any specific wishes for Telerik controls or just how to incorporate the library, etc?

Thanks so much!!

Excellent!! You sound like a software engineer to me, especially getting offended at structure and performance! 🤣 Keep at it, and even if you don't want to leave your current job, there's tons of remote/freelance gigs out there if you want to turn your tinkering into dollars!

Great!!

Thanks so much, I'm very glad its helpful! Will be back at it soon.

You will likely need to bind some ObservableCollection type to your dataGrid and from there create and populate your data so it displays correctly. I don't have anything specific to that yet - but this may be helpful if you are still having issues. (sorry for my delayed response) stackoverflow.com/questions/24539022/how-to-bind-wpf-datagrid-to-observablecollection

Thank so much!!!

Thanks so much, glad it helped!

Thank you!! I'm glad they are helpful. Keep at it, the best way to be a coder is to write code!! 😁

Glad to help, thank you for watching!

Thank you!!

Good luck on the library!! Hopefully I'll be starting back up soon, too.

Thank you!!!

Thank you, hopefully I should be back at it soon!

Thanks!

Thanks so much!!!

Thank you! I hope to get back to it in the next couple of weeks or so once work calms down.

That was quick! So glad you enjoyed them. I don't have any video tutorial references on hand - I really want to do a series on databases when I have more time. Browsing around, I found this, it looks like it covers the important no-frills howtos of C# + MSSQLServer: zetcode.com/csharp/sqlserver/ I think learning this is most important, rather than starting with an ORM like entity framework that obfuscates how things happen. Many times a simple database application, especially a personal one, is easier to just implement yourself rather than take on the extra complexity. From there, if you are interested, you might want to check out additional tools/ORMs like: Dapper: www.learndapper.com/#what-does-dapper-do Entity Framework: learn.microsoft.com/en-us/visualstudio/data-tools/create-a-simple-data-application-with-wpf-and-entity-framework-6?view=vs-2022 If you are looking for a lighter-weight database option, SQLite [flat file, non-server] may interest you. sqldocs.org/sqlite/c-sharp-sqlite/

Thanks!

Thanks!!

It is on my to-do list! thanks!

Sorry for the delay.. really appreciate the thoughts! I will definitely make a deeper look with navigation and data passing/persistence. Many times it can be as easy as maintaining references to your active views' view models, and the data will be held in those objects, but it's close up on my todo list when i can get back into it. Usually for these tutorials I just create a single Window and put logic into it. Window comes with behaviors to start/close the application as well as minimize/maximize/etc. User Control is basically UI space with nothing extra, so its great for separating out pieces, creating reusable widgets, swapping panels, etc.

Thanks, yes navigation and swapping between views/viewmodels are both on my todo list!

@@KampaPlays will be waiting

Thank you, really appreciate that!!

I'll be continuing the series, I will try to start from the ground up to create a whole project.

@@KampaPlays thank you so much, well appreciated

Thank you, hopefully soon!

You would call API/logic inside of the ViewModel itself. That way you can use the results/response to update your UI and your models. You may want to separate the bulk of that logic into another class to be called from the ViewModel if it makes sense to do so.

Thank you, I'm glad it was helpful. I can add this to my todo list!

Thank you. I'll add this to my list, but it may be some time before I get to covering any specific 3rd party packages.

Will be back at it as soon as work calms down a bit!!

Got it :D In Viewmodel: public ICommand delIng { get { return new RelayCommand(param => deleteIng(param)); } } void deleteIng(object ing) { //Do sth }

Thanks! I would strongly recommend using the generic version of the RelayCommand class. It will keep you from ending up with hundreds of lines of duplicated code, and if changes ever need to be made, they can be done in a single place. Expression bodied members are a bit crazy looking at first, but they are an amazing tool in C# I and definitely think it's worth learning! learn.microsoft.com/en-us/dotnet/csharp/programming-guide/statements-expressions-operators/expression-bodied-members

@@KampaPlays That's interesting because I saw this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-bYPU8X8f2xU.html (this is his conclusion) from a seemingly experienced guy, who is also making wpf tutorials. He talks about the pros and cons of creating a class for each command and he also presents an example in which using relay commands would actually result in duplicated code. So I got the impression that it doesn't really matter which way to do it... I'll definitely still look into expression bodied members though!

@@dariostromajer1625 Hey, that was a good watch, and a pretty clean way to do things. I wasn't trying to say it was wrong, but mostly that I would give it a go (especially with expression bodied members themselves) before you go with the other method. I've used both methods with success, but what I've noticed is with a team of people, things can get much muddier faster with command specific implementations, but as long as you follow a good standard and keep consistent I say do what you are comfortable with.

My biggest suggestion would be to pick a personal/work project you want to complete and let necessity drive your learning using the Microsoft available resources. learn.microsoft.com/en-us/dotnet/desktop/wpf/controls is a good place to start, they have lots of information for each component including sample code and examples.

As far as I know, WPF is strictly Windows. There are several WPF-like alternatives that are cross platform though. Check out Avalonia UI. MAUI also is similar, in that it uses XAML, but Avalonia is much closer to native WPF.

Sorry for the confusion -- WPF bindings and commands are one of the more "black magic" things that are hard to see how they work. Those parameters are provided so you can make RelayCommand more generic. You can pass any function to serve as your command action, and any function to serve as your predicate (whether or not you can do that action). So for example, using a button, you can bind a RelayCommand, and provide a "DoThis()" and a "CanDoThis()", and it will handle things like disabling the button based on "CanDoThis()" to running "DoThis()" when the button is clicked. I hope this is helpful.

@@KampaPlays yes I think I understand. What's the alternative? Do you create a new class with new methods for each button?

Are you asking how you can pass something to the Execute method of your command? If so, you can set the property CommandParameter on your button in xaml. You can also do it in code-behind with yourButtonName.CommandParameter = something...

Thank you! Dario's answer is correct, and I will add these to my todo list, as it can be confusing!

Appreciate it. Yeaaaah, life happened. Lots of work and family things. I am planning to return as soon as I can with a continuation of the series and advanced topics, but I have to get past a few more hurdles first! Thanks for watching :)

@@KampaPlays damn, hang in there!

Thank you!! It is possible, but since you can't bind directly to SelectedItems, you have to use another way such as a CommandParameter or custom control. I will add this to my to-dos! This might help clear things up in the meantime: stackoverflow.com/questions/9880589/bind-to-selecteditems-from-datagrid-or-listbox-in-mvvm

Will add it to my todo!

@@KampaPlays Thanks a lot.

Many things in WPF "handle themselves" when it comes to resolution changes -- What are you interested in doing?

Will add to my list of to-dos.

Will add to my todos!

@@KampaPlays please do

This is on my todo list, thanks!

I don't include code with these short, beginner level tutorials. This is to help the most people learn and retain the information. The best way to learn to code is to write code.

@@KampaPlays I have thirty years experience and just switched to WPF. I’d encourage you to include the code because people don’t have time to write code for these. I’m finding solutions elsewhere and now I look for code before viewing.

@@talktodale I appreciate the feedback and definitely understand your point (I don't watch tutorial videos myself, as its faster for me to just reference the documentation). I will absolutely include repos for more complex/lengthy topics, but my primary goal here is to help people learn, understand, and retain. I would highly recommend going straight to Microsoft learn.microsoft.com/en-us/dotnet/desktop/wpf/ and skip videos entirely if you are an experienced programmer, as it has a wealth of example code for everything you might need. Again, thanks for the feedback and best of luck to you.

@@KampaPlays that would be fine but you don't say which version of .Net you are using and although it works with the older versions, it does not work with .NET 8.0

With remote programming jobs being so available, I bet you could get work anywhere! :)

Sure -- kampaplays@gmail.com but honestly I don't check the mail as often as I check comments here!

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