Wire Up the WPF Login form to the API - A TimCo Retail Manager Video 

I appreciate the kind words. I'm also glad you are thinking through the things you would have done differently. Keep that up.

Thanks for sharing.

I am glad you are enjoying the videos.

Thank you!

Thank you!

Thanks!

You are welcome.

You are most welcome. Thanks for watching.

Thanks!

Thank you!

Thanks!

You are most welcome. Thanks for watching.

I know Im randomly asking but does someone know a trick to log back into an instagram account? I was dumb forgot the account password. I appreciate any help you can give me.

@Kenzo Kendrick Instablaster :)

@Jeremias Alexzander Thanks so much for your reply. I got to the site thru google and Im waiting for the hacking stuff now. Takes a while so I will get back to you later with my results.

@Jeremias Alexzander It worked and I now got access to my account again. Im so happy! Thanks so much you saved my ass :D

My pleasure!

You are welcome.

You are welcome.

Thanks for sharing.

YAY! thanks for that, was getting a "Bad request" result, scrolled through the comments here to see if anyone else was getting that, turns out I had done a similar typo over there as well! Thanks for pointing me in the right direction!

@@IAmTimCorey Perhaps we should set up a IAmTimCorey slack / discord as a centralized troubleshooting forum for everyone following along with your courses... As always thanks for the great content! I love your teaching style!

Great!

I am glad you stuck with it and figured it out. Debugging gives you great experience.

there is *nameof* expression...

Thank you!

Glad you figured it out.

Caliburn Micro uses the default of click for attaching the event. If you wanted a different event to fire, you would need to bind to it manually.

Merci beaucoup!!

Does it already have 4.0? I though mine still had 3.7. If you are on major version 4, yes, go ahead and upgrade to the latest 4 version. If you are on 3, upgrade to the latest 3 version.

Well, there is one definite reason to have an interface here and another possible reason. The definite reason is because now you can test a class that depends on IAPIHelper without bringing in the "real" dependency of APIHelper. If we want to create a unit test that tests to see how a class responds to a specific response from the HttpClient, we can do so by mocking the APIHelper class. That way we don't actually connect to the real API and make real calls. We can make fake calls that test what happens in various scenarios. That is the definite reason to use the interface. The possible reason to use an interface is if we ever wanted to swap out the APIHelper library for a different one, we could do so by changing one line of code (which concrete class dependency injection returns when the interface is requested). This keeps the system more loosely coupled.

They have made it a lot easier to develop and test with HTTPS.

I'm glad you were able to expand your knowledge and get this working.

Thanks for the suggestion.

I'm glad that helped. It is a bit confusing.

Awesome! We'll look into the token expiration in the future. Right now, the token is long-enough lived that it won't be an issue (it is days).

Wow... so that was the problem I was having. I definitely did not expect that...

Double whammy for me. I accidently had AcccessToken (notice the 3 c's), then Acccess_Token, finally noticed the extra 'c'. Tim, love your videos, but it would be even more amazing if you pointed out these weird idiosyncrasies about naming conventions.

Here you go: ru-vid.com/group/PLLWMQd6PeGY0bEMxObA6dtYXuJOGfxSPx

They are in a playlist on this channel.

Just set up an event listener on the Password box to listen for the enter key event and then fire off the Login event when it happens.

That comes later in this series (we upgrade everything to .NET Core).

Interesting take. Thanks for sharing.

Way to stick with it.

You would deploy the two projects independently. You would deploy the API to a web server and then deploy the WPF to whatever location it needs to go to.

APIs allow you to be flexible in your application. You can add a different UI later, add a mobile application, or even communicate directly between systems without a visible UI. I recommend them for a lot of situation, even when those situations might not include a web-based UI.

By using an interface, we can change out that class later to a different class. Say we had an UpgradedAPIHelper that still implemented IAPIHelper. We could replace the class in the DI system once and upgrade our entire app. Also, we can replace that class when testing classes that depend on it.

@@IAmTimCorey Makes sense. Thank you!

One instance per instance of the application. Every user, when they open the WPF application, creates their own instance.

That means that somewhere you did not instantiate a class. For example PersonModel p = new PersonModel(); You left off the "= new PersonModel()" somewhere (PersonModel being a stand-in for the class that it says is not instantiated. My guess is that I've got a List in a class that I instantiate in the class like so: List Demo { get; set; } = new List();

Good question. Since it is a WPF application, it is a singleton per instance of the app. So no, that shouldn't be an issue unless we write some type of weird code to step on our own toes. Going forward, though, we might consider using the HttpClientFactory to manage our HttpClients more efficiently.

If you follow along in the .NET Framework, you will have a better experience. This course was designed to start with the .NET Framework so that you could learn it, and so that you could learn how to upgrade a real application to .NET Core and beyond.

@@IAmTimCorey ok, thank you very much. Do you suggest a video for api configuration and authentication with net 6?

There is an option now upon template creation to use HTTPS. This isn't as robust as what is in .NET Core. As far as I know, there isn't an automatic redirection to HTTPS, it doesn't force HTTPS (just enables it for development), and it does not deal with HSTS. So yes, they did bring in more HTTPS support into the .NET Framework in later versions, but the HTTPS story in .NET Core is still much better because it is baked in by default, not an add-on.

@@IAmTimCorey I hadn't noticed the option when creating the project. Thanks for the explanation!

Awesome! Congratulations! I'm glad I was able to help, although you were the one that put in the effort. Keep up the good work. As for Rx, no I don't have a video on them yet but it is on the suggestion list.

@@IAmTimCorey Thanks, I'm looking forward for your Rx videos, your explanation is far the best. Cheers. Have nice day.

Rule of thumb: assume it should not be a singleton. Make yourself prove the need for a singleton before you use it. Singletons are used to persist data for the lifespan of an application. The danger is that they then bloat the memory footprint of an application.

Check out 12:25 and beyond. I explain why I put it there. In the future, we do move it to a class library that supports the UI.

I think he did this just to bring it up to current. He also did this in the beginning of the Configuring Swagger in WebAPI video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zQRgB6nasUc.html

Nicholas is correct.

You mean in the Swagger video? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zQRgB6nasUc.html

We aren't using the interface directly. We are asking dependency injection for the class that it has that fits the interface. That way, we can change the implementation centrally in dependency injection and it will change which concrete type the dependents get.

@@IAmTimCorey thanks. I just thought that since you implemented IAPIHelper in the class APIHelper you would have used that class to instantiate _apiHelper. Again, I am nit fluent AT ALL with interfaces.

Im wondering the same... Must have something to do with the "Can" keyword befor the name of the button

Yes, that is a part of CM. The Can keyword tells the system that it makes the control visible or invisible depending on the output.

Thanks! And I'm sorry? :-)

Yeah, it sounds like a naming issue. Either that or when you called it and did the Ctrl+. to add the using, you accidentally created a new class instead.

I used to when I was doing the deploys locally but now I use Azure DevOps to do the transforms in a similar manner (if .NET Framework) and .NET Core makes even that unnecessary in a lot of cases.

It sounds like there is an old NuGet package or something similar causing an issue. Try doing a Rebuild (not just a Build) and then running it again. If that doesn't work, check out the NuGet packages and see if any need an update.

@@IAmTimCorey Thanks Tim. Turns out my version was not capturing some of the packages for updating. Had to manually update some packages depending on the build errors I was getting and after manually updating the rest, the build went on okay.

@@njogusamuel Hi, I am relatvely new to these lessons. I am getting the same issue (Sep 2020) . My packages (except Bootstrapper 3.X) all seem to be up to date through VS2019. Would you be kind enough to explain how you solved this in more detail please? Thank you!

@@MrDareDare Hi Dan, at the time, when trying to get updates through Nuget package manager, some packages were not being picked for updating. Try going through the logs on your error list, then looking up the versions of those packages on the package manager, and resolve them(i'm hoping they are not that many).

Solved it: The clue is in the error message! You need WebActivatorEx and Microsoft Owin installed as References for TRMDesktopUI using the NuGet Package Manager. These are dependencies that the compiler could not find.

Look at the changes you made inside and outside the app. Debugging and testing are critical skills to develop and this ia a great opportunity.

I believe "How To Call An API in C# - Examples, Best Practices, Memory Management, and Pitfalls" is the video I was referencing

Not sure what is happening. Maybe step through the code from the first breakpoint.

@@IAmTimCorey thanks. Got it resolved, It was the key value of grant_type which I mistakenly wrote it grand_type. It took me hours without realizing it. anyway thanks.

@@joaocorreiafreitas712 I did the same 😂 Thanks for this hint ;)

Are you using the https version of the URL? You should be. Also, try going to it with a web browser using https. Maybe you need to trust the certificate.

This error occurred when trying to run both projects at the same time in the connecting the api video

Not sure. Maybe a bad version of a NuGet package? I'm using VS2019 so that shouldn't be a problem.

Hi did you get any solution?. I am ruuning out with same problem

@@uttamchaturvedi Hey Uttam, Having the same problem. I just rolled back to my previous version of the project. My version now is on par with the end of part 10 of this video series. I'm going to go through this section again and see if I can more easily find the problem, and I'll get back to you if I find anything.

I just did a course in the Foundation in C# course series on data access ( www.iamtimcorey.com/p/foundation-in-c-data-access ). In there, I did a lesson on Entity Framework (Code First). When you do code first, it generates a bunch of SQL code for you. Then, when you do LINQ statements to get data, it creates ad-hoc queries to get the data. You are responsible for knowing what the generated SQL is and knowing how to optimize it because EF Core is still not great at optimization. For instance, one of the big things people love about EF is that you can bring in relationships easily. So if I have a PersonModel that has a list of AddressModels and PhoneNumberModels inside it, I can just ask for the PersonModel and everything inside to be populated and EF will do that. However, the way it does that is that it queries the SQL database for all of the People joined with all of their matching addresses joined with all of their matching phone numbers. That may sound fine until you look at the results. The query will create one row for each person, address, phone number combination. So one person could generate 30+ rows with mostly duplicate data. If you asked for 100 people, you could be transferring thousands of rows across the network. Inside C#, EF will strip out the duplicates and present you with 100 models and you might never know that you transferred thousands of records. If you create your own queries using something like Dapper, you can make much better decisions which leads to much faster data processing. That is why Dapper can be an order of magnitude faster than EF. Now EF Core is a LOT more efficient than EF (the .NET Framework version) and EF Core is getting closer to Dapper in terms of speed in a lot of scenarios. However, EF Core is still something that takes a lot more SQL knowledge to maintain and do well. People often use it as an excuse to not know SQL, which is a big mistake.

It is a similar process. I'm not sure if there is a double convert in your method or not compared to mine. It would be interesting to investigate.

@@IAmTimCorey I'll let you know if I'll get the chance to play with it a little more 😎

You wouldn't inject it in a method. You would do constructor injection or property injection. You can also create instances by calling the container directly (I do that in this course I believe).

@@IAmTimCorey Thanks for the reply! I tried it in a method to see if it was possible, but when it wasn't working Google failed me on the specifics of "why". This course has been fantastic by the way. I'm developing a CRM as a semester long project and decided... with only 5 weeks left to switch from WinForms to WPF. It's exposed a lot about my data library that was insufficient but with your examples I'm improving it vastly! Thanks again!

Excellent! I'm so glad it has been helpful.

ASP.NET MVC doesn't need to do this because it lives in the same context as the API. Everywhere else needs to do this, even MVC applications that are disconnected from their API. We have an API endpoint for getting the token. We are using Swagger to call that endpoint. We end up with 2 databases because I don't like to mix my authentication database with my "regular" database.

Ok Thanks Tim. I understand that Swaager is just a UI for our API. I checked Startup.Auth.cs here I can see the /Token endpoint. I think aspnet identity is doing all this for us.

That grant_type will get you every time.

The API security wall? Done.

Sorry, never mind. I got it working now. Thanks.

I’m glad you figured it out.

Not sure if that's the problem but: Make sure to right-click on "References", click "Add Reference", a Dialog opens, click "Assemblies" on the left and then search for "System.Configuration" in the top right search bar.

We probably should have. In looking at it, I don't see a reason why we didn't.

Why are you setting your base address to be a blank URL? If you don't have a base address, don't set it. It isn't pulling from the app.config file here.

Were you able to solve this? I am getting the same error. Edit: Fixed it. I also had this line by mistake: apiClient.BaseAddress = new Uri(""); It needs to be changed to: apiClient.BaseAddress = new Uri(api); where we are receiving api address from the app.config

I found something. The problem seems to be the password itself. It contains $ and that seems.to be the problem. The same password works via postman...

I'm glad you figured that out.

I will answer my questions:(But I would be glad to hear a short answers from you also) "Our initial project is we need to build a desktop app that runs a cash register handles inventory and manages the entire store". "In order to grow we will create a WebAPI layer" Because for now we want a desktop app but it makes sense that tomorrow our client would like to sell online, using WebAPI layer will help us to cover and achieve this new requirement fast. "The WebAPI layer is going to service a desktop, web and mobile application".

Yep, you answered your own question (well, I guess I did, but you found that part). Initially, setting up an API can be a bit of extra work. However, by doing so, we set ourselves up for the future, where we can be resilient in the face of change. To give you a picture of the future of this application, we will upgrade to .NET Core. Because this is broken apart as it is, we can upgrade each project one at a time instead of needing to do all at once. Next, we are going to upgrade our projects to .NET 5. The cool thing is that this is as far as the WPF project will go. It will not progress to .NET 6 (or at least, that is the plan). However, it will continue to operate just fine even as we upgrade our API to .NET 6 and beyond. After the .NET 5 upgrade, we will be adding at least one, but probably two different user interfaces (Blazor WebAssembly at least). They will use the same API. There will be some additions to the API, which the WPF application may benefit from as well, but the core calls will stay the same. If there is a bug in the API, we can fix it and the fix will benefit both user interfaces. After that, we will be utilizing microservices to make our API more powerful and more capable of handling growth. That won't affect our user interfaces at all. Finally, by using an API, we can safely deploy a WPF project to the end users without giving them access to a database connection string or other sensitive data.

@@IAmTimCorey Thanks Tim

I am glad you figured it out.

It is quicker. That's about it. It is up to you if you prefer to see the full type or not.

@@IAmTimCorey Thank you!

You can only use var when you know the type anyway. Thats what it is for.

I had username and password parameter in the LogIn method, which were null when LogIn button is clicked. So context.UserName and Password were null, so user was always null. I have removed these parameters and user the properties. It works now :) Thanks

I am glad you figured it out.

@@vivekacharya3110 I have the same issue . Thank you !!! but in my case it null only password that send to Login method.

and it has explain in the previous video.

Well I managed to find the problem. Got it all working.

@@tanzib82 I have the same problem how did you solve it?

@@tanzib82 could you please explain what you did? I am having the same problem and I am just banging my head against the wall

@@jasonm5995 hello, honestly I do not remember what I did. Ill look at the project again see if I can remember.

I just renamed "AccessToken" property inside the AuthenticateUser class to "access_token" and it worked.

You will have to debug to figure out why.

Windows 7 is still strong and will be for the next 5+ years

@@DamianWalczak Almost all of my customers are running Windows 10.

Corporate moves a lot slower the larger it gets so having Windows 7 is not uncommon. In fact, there are still organizations I work with that have large installations of Windows XP (shudder). However, there is a larger reason why I stick with WPF: simplicity. What do you expect from UWP that is better than WPF? Unless you are planning to distribute the software through the store (which isn't a good idea with corporate software), I don't see a benefit. It is limited to Windows 10, unless you side-load the app, it isn't something you can distribute easily, and you are more restricted on what you can put in your application. UWP is mostly for if you want to have your app work on the XBox or if you want to distribute through the Windows Store.

@@seanmiller7889 "Almost"

In Corporate there is never the question to use UWP. Be Happy you can stick with WPF and propably will for a loooong time :) You stick to WPF for Windows or you go QT with C++. UWP Should never be an Option

This is a more advanced course. We are using techniques I've covered in other videos so you should be able to find tutorials that will get you up to speed.

I'm not sure. You will have to do some debugging. Something is different. Have you tried logging on using Postman to see if it gets the same result?

Hi, Anthony! Make sure that you don't use camel case for access_token. The response body seems like: { "access_token": "", "token_type": "", "expires_in": , "userName": "", ".issued": "", ".expires": "" } Ensure that you use the right naming for the properties in your AuthenticatedUser class public string access_token { get; set; } public string userName { get; set; }

@@spolus Thanks, had the same issue and this solved it

​@@spolus I hat the same problem but the reason was that I accidently created the property Access_Token {get; private set;} -> with private setter it surely fails. Your solution is interesting. Tim did name it Access_Token and UserName. Same did I and it runs.

@Pavel Solomin You are a life saver thank you!!

Found this issue. I had to make the interface public.

Good catch.

The LogIn() method is now an async method. If you call an async method without awaiting it, you will not get the return data (or capture any exceptions). That's not a good thing. You can use the ".Result()" on an async method to call it synchronously but that typically isn't a wise idea because you are forcing something that should be async to run synchronously.

You can watch all of the videos in order if you use the playlist: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Xtt6mS0p2_c.html They are labeled as to what each of them does in case you want to watch just one specific one.

Thanks for sharing the idea. It's always clearer when we look back over the work.

@@tomthelestaff-iamtimcorey7597 found you can use Trace.WriteLine() to log to the output so guess it is built into WPF already. Just failed to Google it properly

Yes, that's the plan. We are developing in .NET Framework so that we can demonstrate how to port over an existing application.

lol, it happens to all of us.

Hi Tim, I already got the solution for this one. I thought it was deadlock causing me the issue, the issue is on SSL/TLS. I'm using a VS2019 and everytime you create a solution with Individual Authorization it automatically adds up the HTTPS. Anyway, thanks for your awesome videos will continue this course.

Glad you got it figured out.

@@IAmTimCorey I really appreciate your videos and it helps me to expand my knowledge and force (in a good/positive way) me to know something I don't know.

Hi Julius, how did you manage to solve the issue? Thanks Mark

@@markboylan9215 My solution was: In Solution Explorer, right click on WebApp project (TRMDataManager) and click Properties. Under the Web Tab, change Project URL from https to http. Save changes. Next, in App.config file, under , for key="api", change value from localhost to localhost. Save changes. After doing these changes I got response from HttpResponseMessage. Hope it helped! Good Luck!

You mean that the username and password you are trying to capture from the form are null? It sounds like you have a naming issue between your property and your TextBox.

@@IAmTimCorey No, at api side when i am post my username and password to generate token for user, (Token/Create) method receive username and password as null. With postman everything work fine.

We haven't added them yet. This project is meant to be a real-world simulator. So, we started with .NET Framework so we could upgrade to .NET Core. We also started with no unit tests so that we could add unit tests to an existing project (something very few tutorials cover).

Great catch

I have a video on EF best practices on this channel that covers more about EF and my reluctance to use it, especially when training others. The simple version is that EF takes a lot of skill to get right. It is easy to get it working, it is hard to get it right. That's the big problem. I have seen too many apps that work in development that then cause major problems in production (when it is too late to change). I prefer to use Dapper because it doesn't hide bad code. You are forced to write good SQL. Also, by writing your queries in SQL, it is much easier to improve them compared to ad hoc queries from EF.

@@IAmTimCorey thanks, Tim. Agreed that EF does make getting going easier, perhaps much easier. I suppose one could suffer from if you don’t know what you don’t know…

when I do this trough swagger,its ok but from login form I always get bad request

It sounds like something is different. Are you marking the grant_type as password? Are you send a POST request?

@@IAmTimCorey I found a bug :D Instead of grant_type,I wrote grant-type hahahah

I like it. Way to push yourself to learn.

@@IAmTimCorey Oh yeah, I'd rather sit and look blankly at the screen for an hour and eventually figure it out then do a copy pasta! Shout out from the the Garbage Collectors Discord! Quite a few of us like your stuff. Even some of the experienced guys approve of you 🤣

Forgot to add that searched though the comments. found others with what seem to be the same or similar issue. but those answers did not work for me.

Got it! rename of ApiClient to apiClient failed to rename all uses in the code.

I'm glad you got it figured out.

I think the reason is the Nuget versions compatibility but I still have other types of execption when I play with the versions

I'm running into the same issue 😟

@@Thunderbuck if I remember it was a nuget version problem try to use the same nuget versions that tim use

@@aymanawadallah6948 Hmmm. Already using the same versions but for Newtonsoft.Json, and I've rolled that back now and it didn't fix. I'll have to dig in :-)

That's a pretty generic error. You are going to have to do some digging to figure it out. The good news is that this debugging process is actually one of the best teachers when it comes to programming. Try not to shortcut the process. Track down the error by narrowing down what it could be. At the very least, you should be able to get a more descriptive error statement. From there, you can either fix the problem or at least be able to have enough information for someone else to point you in the right direction.

For everyone that comes with the error 'System.Exception' in mscorlib.dl'. It means that your call to the API is returning a "Bad Reques' because some of the keyValuePairs does not conform to the API parameters. So check you key value pair. Mine is missing the " " (two doubule quote) on the password string on the grant_type.