C# Dependency Injection with Autofac
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- เผยแพร่เมื่อ 27 ก.ค. 2024
- Dependency Injection in C# can be a really confusing topic. Yet, when done right, Dependency Injection can be one of the best things you do for your application. It allows you to disconnect pieces of your application from each other easily and it allows you to test the various parts of your application independently. Today, I am going to get you started using Dependency Injection using a free tool called Autofac. We will take a small sample application and first apply the Dependency Inversion Principle (the D in SOLID). Then, we will wire up Autofac to handle connecting the various dependencies together.
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0:00 - Intro
1:17 - Demo code overview
5:00 - Refactoring demo code
9:19 - Implementing Autofac: Adding the reference
10:28 - Implementing Autofac: Setup
26:39 - Implementing Autofac: Code explained
33:21 - Recap
36:43 - Why to... : Unit Test
40:33 - Why to... : Changing the code
48:31 - Summary
50:29 - Concluding remarks
This world is blessed to have you man. You have a tremendous skill for teaching. Explaining every bit, every key stroke, every decision as you go. Wow! I wasn't expecting to learn so much.
I appreciate the kind words.
The clearest tutorial ever about autofac! Thank you Tim!
Thank you!
I Can't believe how good these tutorials are, I'm genuinely learning so much! I've got a job lined up at the end of this month and i'm going in confident because of you!
That's awesome! I'm sure you will do great.
I genuinely appreciate your effort to make this stuff easy to understand, and so comprehensive. You are the man! God bless you!
We are glad it helped you.
I have been writing codes for 3 years,
Been so blind all these time, Thank you sir, gonna watch all your lesson one by one
I am glad you found my content to be so valuable.
As usual I have no idea what I was doing but after watching the video a few times, I'm getting a better understanding over the subject. So thanks Tim.
Excellent!
This is the most powerful concept I've learned in your SOLID principle videos. Thank you for the detailed breakdown, clear explanations, and realistic examples of how this can be so incredibly important.
Appreciate the feedback
Awesome content Tim as always. The last few comments you have each video are really what makes a difference. Because of this, we are able to summarize what we understood.
Great to hear!
Thank you that's the one I was waiting for
Same
Excellent!
Thank you very much, Mr.Tim. From now on I'm gonna use dependency injection in future projects.
Great!
I have rewatched this video twice, one at the beginning - nothing was clear, and now it is more clearer! Danke!
Glad it helped!
This lifted so many clouds for me. Thank you. Great videos. This is becoming one of my favorite channels
You are welcome.
I've been struggling with this concept for a while now and to see you set it all up and explain the code paths makes it so clear!
Awesome! I'm glad it helped you clear up the confusion.
This video is amazing! You're amazing for making such quality content videos.
I started watching your videos recently, ".NET Core vs .NET Framework - What's the difference?" was my first video and I can't thank you enough for making these topics comprehensible
Wow, thank you!
Thanks Tim!
I have been trying to get my head around Dependency Injection for quite a while now in my quest to become a developer. Out of the numerous videos and documents I have read about the topic, they have only shown me syntax and examples but not explained it. Your videos are so clear and concise at demonstrating and explaining these concepts that this is the first time I can walk away from a DI video with an understanding on where I have been going wrong.
Pretty sure this is my first TH-cam comment, but I just wanted to show you my appreciation for the time and effort you are putting into your courses.
Awesome! I'm glad it connected with you.
Really appreciate that no ads in the middle. I have pluralsight member, but found yours is much better!
Thanks for watching and sharing your thoughts!
Thank you so much for this!! Watching you teach beats reading documentation any day
You are so welcome!
0:00 - Intro
1:17 - Demo code overview
5:00 - Refactoring demo code
9:19 - Implementing Autofac: Adding the reference
10:28 - Implementing Autofac: Setup
26:39 - Implementing Autofac: Code explained
33:21 - Recap
36:43 - Why to... : Unit Test
40:33 - Why to... : Changing the code
48:31 - Summary
50:29 - Concluding remarks
As always, thank you! Added to the video comments. It will help many others, I am sure.
For the love of god, just take my money when I sign up over at Patreon! this was awesome. Sometimes getting back to the basic principles like this one is so important.. Depending on the project you're on, you can program with blinders on for way too long... These videos get the core principals back in your head and makes life so much easier! Thanks!
Awesome! I'm so glad they were helpful.
Definitely the best video on Dependency Injection / IOC I that I have seen. Watched about 12 over the past year, because I knew I needed to integrate it into my code. I couldn't quite figure where the value adds were or exactly how to implement properly, because I work by myself and am entirely self taught.
Finally an explanation that makes sense!
Awesome!
31:38 🤯 Been using dependency injection for a while on an inherited project, but how the constructor was getting the the variables instantiated were a mystery to me. I finally understand.
Awesome!
Hi Tim! Thanks for this very good video about Autofac. I'm reading aout autofac to migrate from Unity because it's recently deprecation. Do you recomend actually Autofac or do you think at the moment there are a better alternative? I'm searching also for a Prism WPF application and Autofac is not supported because it's an inmutable IoC container, for Prism it seems that DryIoC is the only alternative. Thanks in advance!
There is built-in DI in .NET Core.
Best explanation I found on the topic from over 7 videos I watched!! Thank you very much!
Also the one explaining Dependency Inversion! Shared with my friends!
Glad it was helpful!
Thanks, Tim Corey. I now understand Dependency Injection. I love how you explain things with examples.
Great!
The best ever teaching style and tutorial that I ever visited or go through on youtube. Very fantastic with each and every bit of detail. I really liked your slow-motion teaching style which is very helpful to understand for non-native english speakers like me. This is my first time that I visited your channel and when even I was not in the middle of this video, I subscribed your channel. I would like to suggest I mean request to make tutorial on other Enterprise Application Patterns especially (MVVM,Communication between loosely coupled components, Navigation, Validation, and other topics given at the link: docs.microsoft.com/en-us/xamarin/xamarin-forms/enterprise-application-patterns/), I will also suggest to make a code map of the given tutorial and summarise the whole topic at the end of the video, that will be really helpful to memorise the whole process. From now to onward, will wait for your upcoming series.Many Thanks
I'm glad you are enjoying the videos. Thanks for the suggestions.
How would you do this for classes that need arguments passed that are only known at runtime?
Another masterpiece from you Tim, state of art, amazing job you’ve done. Thank you so much!
You are welcome.
Great Video! I've been watching a whole lot videos about DI, yours is the only one that I really understand. So much thanks.
Awesome!
Thanks!
Thank you!
I REALLY want to pickup on Blazor WASM which has DI Baked in. I've avoided DI for years as I felt it was never worth all the extra work and overhead let alone the time learning it. Not only that, it also seems to add an additional layer of complexity when troubleshooting issues... DI really seems to obfuscate things... but that's probably my inexperience with it.. I just hate that they baked DI into Blazor... I was hoping my years of experience with Asp.Net MVC would smoothly translate but not with DI! I can understand why it's baked in for projects both a client and a server it makes sense. You explain this all very well and it is understandable, but my goodness it seems like a lot of work for a little!
Yeah, I am reading through comments to see whether I am alone with such thoughts, I think dependency inversion is a great thing to do with factory etc, but to use third-party library and have this magic working on - I don't really see the benefits over doing with hands
After a while it becomes habit and it is second nature. Without DI I imagine you don't unit test everything?
@@movsar42 how do you mock the 3rd party library if you don't use DI?
Every time I search for a programming explation tutorial and see your name I immediately pick it up as one of the first videos. Here is what is great about your videos:
- a nice voice to listen too and I just know that you used good quality mics
- video quality is great and sharp to look at even on mobile
- probably the best thing, you stop and explain things slowly and guide the user through the code instead of rushing it. And just when you have explained it, you repeat it again in an even slower pace and using simple phrases. For me personally, slow explanation and repetion is what sinks deep in my brain for long term storage :)
- sometimes what I miss from your tutorials is drawings and figures to explain the concepts. A figure really tells more than a 1000 words and many people remember concepts easier when they are visualed in a simple way.
I am glad you enjoy the content. I agree on the drawings and figures. I just need to figure out a way I can do that easily (so it doesn't take up my entire week).
Great video. One of the best explanations I've seen of dependency injection, with a code example simple enough to see it working. Also, highlighting the two main reasons for using DI.
Thank you!
Hi Tim!! I reaally liked the video!
There's one thing I don't quite understand: what if, for example, the Logger class had a constructor that needed parameters, like a string dataBaseOfChoice? Would I have to make the constructor parameterless and set the dataBaseOfChoice through a property or something? In your examples you tend to use constructors that use other classes or interfaces which have a parameterless constructor, so I ended up having this question.
Generally we use parameterless constructors. However, there are ways to use parameters but they aren't as easy as you might want. Remember that if you are using dependency injection, the system needs to know that information on startup, not later on. Usually it is easiest to bring that type of configuration in from a config file or by checking a setting somewhere.
@@IAmTimCorey Ah, I see. Thank you!!!
I have a question: How Autofac resolve 2 Types with the same Interfaces. For example: I want to use BusinessLogic when a checkbox is not checked and BetterBusinesssLogic when a checkbox is checked. By the way great explaination, i really like this video and your playlist about SOLID
There are a number of ways. You can use a named service, you can use metadata, you can use decorators, or you can even just get a list of the types. Their documentation covers each of these scenarios. I hope to cover them in a video at some point although it will be a while.
Thank you, I watched many free course on this and didnt understand it. Now I understand it really well and can start programming this way at work :)
Excellent!
Thank you so much Tim! Ever since your D in SOLID video I've been doing constructor injection everywhere. But I've been newing everything up myself in the main class. Even so, I thought I was living the good life. This will make things even better! Excited to start using Autofac.
Awesome!
Great video! One question about something that's been bugging me:
Dependency Inversion seems great, but what happens when you need your Interfaces to implement new behaviors you didn't foresee? Now you gotta go through every class which implements that interface and refactor. Are there good ways to mitigate or avoid this? I guess what I mean is that I always feel like I'm forgetting something or not future-proofing myself when I design Interfaces and that I'll be going back and adding/editing code; the very thing I was trying to avoid doing by using Interfaces and Inversion.
Other than that, Interfaces really are amazing.
Good question. First, this happens less than you would think, or at least it has less of an impact than you would think. Usually you don't have an interface that is implemented a hundred times that has to be added to. Usually it is much smaller (say less than five implementations). Think about IDisposable (provided by Microsoft). That interface is used all over. However, that isn't something you want to change. If you wanted to expand upon the interface, you might have another interface implement IDisposable and go from there.
Second, changing the interface is a minor thing (the actual interface, not the implementations) but if those implementations really do carry out the interface, they all would need to be updated even if you didn't use an interface. Let's take a data access interface for example. It has a method called LoadData and you have two implementations (SQL and Oracle). Adding a SaveData method definition to the interface means you need to update both implementations but wouldn't you need to anyway? If an interface really does need to change, the underlying objects would need to change anyway. This way you get an error message if they aren't changed (vs not knowing about it).
When it comes to DI, usually we have very tight interfaces to classes (typically a 1:1 ratio for most things) because that is how we load the classes into the DI container so changing an interface is really easy.
Thanks for the reply. That all makes a lot of sense, particularly since most of my Interfaces aren't used on many classes anyway. It's all better than the alternative, which is to not have DI at all!
Tim. How does this one compare to the one Microsoft includes in the Entity Framework? Microsoft.Extensions.DependencyInjection
The built in DI is mostly used in .NET Core but it can be used throughout .NET. However, it is a lighter version of DI than Autofac or other dedicated DI platforms. Definitely nothing wrong with it, but if you need more power you would need Autofac (or similar).
Excellent! This really got me over the hurdle that I frankly have had for a long time. I could use DI but really didn't know what I was doing!
Awesome!
Just wanted to say thanks for the tutorials. You have a knack for easily explaining things that can be difficult to understand.
You are most welcome. Thanks for watching.
Good tutorial. Would be nice to see real life application using dependency injection with mvvm. How and when use DI. Thanks.
Thanks for the suggestion. That might come up in the new course I'm releasing on TH-cam (TimCo Retail Manager).
Hey Tim, what if i have multiple implementations of an interface?
It depends on what you want to do. When you ask for IWorker (an example), and you have four classes that implement IWorker, which one would you expect to get? Either you tell dependency injection about only one of them, or you return a List with all of the instances. Another option would be to specific a specific instance based upon another value. That's a more advanced case, but it is possible.
@@IAmTimCorey Autofac might allow naming different implementations for the same interface.
I recently watched your series on solid, and so I'm glad to see a tutorial on dependency injection.
Great!
Awesome tutorial :) I trying to watch all videos one by one . Thanks a lot for putting so much efforts for our learning .
So nice of you
how can we donate to you tim? do you have monero address or a bitcoin address where i can donate?
I really appreciate that. I set up Patreon so folks could contribute. You can also purchase a course (links in video comments). You contribution allow me to continue to make the free training on TH-cam. Thank you!!
Thank you so much, finally a simple explanation of Dependency Injection. I had hard time to understand it through many other people explaining it.
Excellent! I'm glad it finally clicked.
Thanks Tim for dedicating your time to building easy to understand c# tutorials. Am learning a lot through you.
You are welcome. I'm glad you are learning a lot.
Great. Dependency injection done automatically, through the autofac without sending it explicitly in constructor. Thank you so much. @IAm Timcorey
You are welcome.
Thanks Tim, another excellent, clear and easy to follow lesson! Your videos are always great to revisit so programmers can hit their own "refresh" button and really listen to that nagging voice in the back of our heads trying to remind us to think about future manageable scalability and not just rush to beat another deadline!
You are welcome.
This video was great. Really helped me quickly understand Autofac usage, and the justification of using it for dependency injection. Really cool stuff. Sub well deserved
Thank you for the very gracious comments and encouragement.
That's wonderful, Tim. I'm going to refactor my entire application!
Great! Just take it one step at a time.
Hi Tim. i just wanted to thank you for the great content you are making. This video and the dependency inversion video just made this topic so clear to me. Just inject everything trough the constructor and DIcontainer will do the rest. so easy
Awesome! I'm glad you got so much value out of them.
As always , so thoroughly described , and easy to understand , really love these videos! Thank you Tim !!!
Glad you like them!
Awesome! Best explanation and it's use that I've heard in many years!
Glad it was helpful!
Very good explanation TimCorey. Thank you for making this video. It helps me to understand DI very well.
You are most welcome. Thanks for watching.
This really is powerful! Thanks for clearing it up, Tim!
Glad it helped. Thanks for trusting Tim
Excellent! Everything straight to the point and I now I understand how the dependency injection (DI) tool works. I attended company's training 6 years ago, where the senior system analyst kept mentioning about the IOC concept but sad he is Java background. We have no clue how to do DI using .Net practically, and that time there is no much online resources about .Net DI.
I did some interface classes sometimes to play around in switching different database drivers, data logging and business logic classes buy manually initialise the object in a configuration class. This seems to be manual dependency injection if I not wrong.
Besides DI, interface also helpful sometimes when I want to do something similar with a group of classes inherited from different parents. For example, I write a form data binding class to get and set value for every field control from different companies like Microsoft, DevExpress and Telerik. An interface with get() and set(value) methods can help to achieve this.
I am glad it was so helpful and yes, you have the right idea with interfaces. They are REALLY useful.
Thank you for this great illustration on DI, I just wanted to say that you simplify the concept of DI = R1.R2.R3 which are R1 = Register, R2 = Resolve, R3 = Run, you are great.
Thanks for that!
Thanks a lot Tim for explaining the basics of Dependency Injection with very good clarity.
You are welcome!
Thisbis a great demo to understand why disconnected architecture is so important , i liked how simply you managed to convey the idea which is definitely very good for those wgo are new to the concept and for experienced professionals to revisit the basics of the application architecture.
Thanks for sharing..
Thank you!
Just what i was looking for, Perfect timing. Thanks
Awesome!
You are .NET & C# knowledge mine! So simple and so satisfying explanation! I will definatelly buy one of your courses when I will save some money:D Keep on with your amazing work!
THANKS!
You are most welcome. Thanks for watching.
You are good at what you are conveying, It is one of the best thing a teacher have and yes, You are a great teacher.
Thank you!
Tim, these videos are amazing. Thanks a ton for taking the time to record them, and for making them available here on TH-cam. Thanks to this vid, I have a better understanding of dependency injection, and how to wield it in my applications. Time to rebuild and play with the code!
(BTW, Autofac was on 81.2M downloads when I watched this. Quite a few more than the 12.9M downloads it had when this video was first recorded/uploaded. I wonder how much this vid helped add to that number?)
Thank you for watching and commenting. Your support is greatly appreciated!
Thanks Tim. You always make these concepts super simple to understand.
You are most welcome. Thanks for watching.
I used MVC and know DI for a long time, but your video makes my understanding much more deeply.
Awesome!
Outstanding tutorial Tim! thank you, please keep up the exceptional work!
You are most welcome. Thanks for watching.
Finally I could understand Autofac. Your video clarify much things. Thank you.
You are most welcome. Thanks for watching.
Omg. Mind blown. This was an awesome tutorial. I have so many plans for this concept for my game engine. Thanks so much!!
You are welcome.
Precise video on Dependency Injection on TH-cam. You deserve more views!
Thank you!
This explanation was so much clearer than the one that Microsoft published... thanks Tim, I’m gonna try this out!
I am glad it was so helpful.
Crystal Clear Explanation on DI after watching multiple videos
Thanks for watching
Thanks Tim, I was waiting for this...
You are welcome.
This is such an hard concept to grasp as a beginner, at least it was for me. I watched your class factory video tried to implement it in a small team project and there were millions of issues. But after learning what reflection is and studying SOLID's in general this video makes perfect sense now. You don't realize how useful this is until you try to implement it manually and struggle. Once again thanks for being such an useful and cool mentor for all us beginners which are trying grasp these concepts for the first time.
I'm glad you pushed through the difficulty and stuck with it. Nice work.
Bravo Bravo.The best explanation ever
For first time it looked scary,but close to end every step was understandable
Excellent!
Thank you very much Tim! you are great explaining things
I came back to this comment section to apologize for my negative comment about this video as i said "this is the most confusing way to explain dependency injection" as what I said was false, and was due to my lack of understanding of some of the fundamentals of DI. After watching this video again I would say that it is a very good tutorial. Thanks Time
I am glad it finally clicked.
IAmTimCorey it sure did, thanks a lot Tim. And again I apologize for my previous comment
No worries.
Thanks Tim . Best video I have seen on dependency injection
Thank you!
I've read about DI a few times in the past. Every single time, i ended up more confused than i started. Now I finally actually understand it...and realised that i'd been doing it for some parts of my projects already, manually (without autofac or similar)
Excellent!
This was honestly amazing. I was surprised by the end of this lol.
Awesome!
Very nice job on making an "abstract concept" more concrete! Thanks
You are welcome.
I just got it, literally a week before I start a junior .NET dev job. Phew just in time.
Awesome!
Great tutorial. I am going to continue with more of them from your playlist!
Great!
Fantastic work! Thank you for a detailed explanation of DI containers.
You are welcome.
Great explaination. Finally had my concepts clear about dependency injection.
Great to hear!
I must admit, I was skeptical over this video to being with - being almost an hour long and I just want information fast.
But, I am really glad I stumple upon it, cause it gave a lot better understanding than most video I had found so far, thanks. Ill subscribe from now on. :)
I am glad it was helpful.
Spectacular video, clear and easy to follow. Thank you!!!
You are welcome.
Hey Tim, I recently subscribed to your channel. I must say all your videos are really great. I watched your dependency inversion principe video. that cleared some of the doubts i had in regards to IOC. This video is informative too. I really appreciate your effort. Keep up the good work. Thanks
I am glad you are finding it so valuable.
Damn, Tim a f****ing Legend! I am watching this tonight, to become an expert is a must for me.
Thank you.
Fantastic one!! It completely explains the core concept.
Glad it was helpful!
What an Explanation!!! Thanks a lot, sir, for sharing this priceless knowledge.
You are welcome.
This was a perfect explanation and demonstration, thank you!
You're very welcome!
Awesome explanation of IOC! Thank you for the lesson.
You are welcome.
A big Like for this video!
I was picking up someone else's project at work, which as written in this way. Now I get the point of it. :)
Excellent!
Perfect Explanation . Many Authors must follow this style
Thank you!
Thank you so much . Finally found this very simple and clear video about dependency injection
You are welcome.
What a tutorial. I understand every bit and piece. Thank you sir.
You are welcome.
Amazing demonstration, Tim.
Thanks!
Thanks for this video! It helped me a lot to better understand dependency inversion. Thank you so much!
You're very welcome!
Great job as usual, this video and your SOLID vids have helped me a lot!
I'm glad they have been helpful.