ASP.NET Core 2.1: Building a Simple Web API

This tutorial will take you through how to create a simple .NET Core 2.1 Web API our demo will focus on creating an Inventory Store to Add and Get items. As we go through this video we will explore some of the new features of .NET Core 2.1
If you have a question, email me at [e-mail]
If you liked this video, share, like and, subscribe.
Subscribe To My KZbin Channel: bit.ly/2eEfYkY
Visit my blog site: danieldonbavan...
Connect with me on social media:
Twitter: / donbavand
GitHub: github.com/don...

[@1evh]

Very good introduction. Thanks. If I could make a suggestion re naming convention, particularly Number? I find it easier to read when the number of the class name matches the intent, so a Class is typically singular and a Collection is typically plural: - InventoryItem - InventoryService - AddInventoryItem() [singular, because you’re only adding one] - AddInventoryItems(List) (plural, because you’re adding more than one] - Dictionary _inventoryItems [plural] - GetInventoryItems() [plural, because you’re returning a collection] Just a thought...

[@DanielDonbavand]

Completely agree, mistake on my part.

[@1evh]

Daniel Donbavand Thanks mate. Glad that the comment adds value. No need to characterize it as a Mistake though - it’s still valid, maybe just not optimal... All the best!

[@soho1080]

Nice and simple introduction to the topic! v cool.

[@kishan2307]

Great tutorial! That's how most production app looks like.

[@default632]

note 3.1 is out, so is this still applicable?

[@rochilds969]

This is necessary disable SSL in Postman. File>Settings>General>SSL Certificate Verification "OFF"

[@tylios2]

The only Thing that missed for me, thanks a lot

[@R4Z0R99]

Thank You

[@shiviselin]

Excellent video. Thanks Daniel, I was able to run the Core API successfully. A great start into a new technology.

[@rockingvirdi96]

Very well done

[@hbgl8889]

For an API I would not recommend doing HTTPS redirects or any sort of URL normalization redirects (trailing slash, lower case URL, etc). Many clients will not resend all request headers on a redirect and you will lose important headers like Authorization. Either accept the request or reject it with an error code.

Excellent!! Especially the postman part.

[@DanielDonbavand]

Thank you!!!

[@kevinm8865]

Agreed!!

[@STUPIDYOUTUBE_HIDINGMSGS]

Thumbs up!

[@ianjames6193]

Fantastic dude ... exactly what I needed.

[@xjdn-34-gdndnk-45-aa]

Ooh nice! Thank you a lot! Just exactly what I look for! After investigating a few hours of your 15 minutes tutorial(you make everything fast using IDE features, without any detailed explanation) I understood the basics of building rest API on C#. So, I subscribe on your channel! Could you please make another tutorial using some SQL or MongoDB, maybe Redis for some maybe simple shop or something like this? It will popularize you channel a lot :)

[@MITHUNROYabir]

Thank you so much. Please upload more about Production level CORE 3.0 REST API Architecture

[@jeremiahalde8375]

hi please help me got this error. Severity Code Description Project File Line Suppression State Error CS1061 'IInventoryServices' does not contain a definition for 'AddInventoryItems' and no accessible extension method 'AddInventoryItems' accepting a first argument of type 'IInventoryServices' could be found (are you missing a using directive or an assembly reference?) InventoryService C:\Users\jalde\source epos\InventoryService\InventoryService\Controller\InverntoryController.cs 25 Active

[@ijeomaenem2671]

Very nice video. Thanks Daniel

[@JonoSchoeman]

Great! Exactly what I needed! Keep it up!

[@STUPIDYOUTUBE_HIDINGMSGS]

Thank you! Great tutorial, simple, easy-to-understand and follow. Can you make a follow-up on this to use SQL database perhaps? :)

[@saifmirza2611]

I followed this step by step but for some reason I get an error on Postman saying 404 not found

[@c-wa]

Came here, looking at the view count. Unfortunately had to quit the video just after about a minute or so, as it was too hard for me to follow this thick accent. Wish I understand this some day soon.

[@bigchunk1]

No need to use [FromBody] in the parameters of your post method? No raw string parser? I guess I did it the more hacky way. I'm assuming this is the better way to do it.

[@deepz513]

Great Tutorial thank you, for netcoreapp3.1, it worked with only Project profile, where I could give a https url and it automatically added SSL certificate on build. In start up class I had to add services.AddMvc(options => { options.EnableEndpointRouting = false; }); For some reason I was not able to make it work with IIS Express profile

[@aubame-bloodclut-zette6745]

do you have the code for this somewhere? I'm getting an error regarding the service variable, because we implemented the the add and get methods in the InventoryServices class but we are setting our service variable to type IInventoryServices its saying that the methods haven't been implemented can anyone help?

[@MaxTaylorHayden]

Great tutorial, thank you!

[@4Siblings313]

Awesome, excellent tutorial. Keep it up dude :-)

[@iceniveth]

Should it be that when inventoryItems is null on AddInventoryItems will return BadRequest instead of NotFound? Seems that NotFound doesn't make sense since we're creating an item instead of looking up. Or am I missing the point?

[@DanielDonbavand]

Yip, great call.

[@ihorbond]

good catch!

[@vanthiennguyen4135]

how to install Postman

[@binzigo]

tks but why I got error when I typed CompatibilityVersion.Version_3_1. It does not show suggestions as usual so It gets an error says " 'Startup.CompatibilityVersion' does not contain a definition for 'Version_3_1"

[@ma-arufburad8826]

Great tutorial bro!

[@jackyloo653]

That's a very awesome tutorial video for a beginner like me! Thanks Daniel! Btw, may I know why did you inject the service layer using DP rather then instantiating the needed service object in the controller itself? Is there any benefit of doing this or this is a recommended practical way of writing code in ASP.Net Core?

[@DanielDonbavand]

Thanks Jacky. Dependency injection helps us develop loosely coupled code. "DI is a technique to create a dependency or dependencies outside the class that uses it. The dependencies are injected from the code that calls the class and any information about their creation are kept away from the inside of the class. This is also why DI is an implementation of the Inversion of control (IoC) principle." reference www.codementor.io/mrfojo/c-with-dependency-injection-k2qfxbb8q Extra reading/information: hackernoon.com/solid-principles-made-easy-67b1246bcdf - Have a look at the "D" part of the SOLID principles www.codementor.io/mrfojo/c-with-dependency-injection-k2qfxbb8q I hope this helps. Thanks for your comment and for watching my videos :)

[@shanthureddy4234]

Thanks , better undestanding :)

[@cineksuw1]

Hi Daniel ! I watch and make step by step this tutorial but i have problems in 9:30. My Visual Studio after clicking _services dont create public InventoryController. Why is that? When i write it by myself i get " Error CS0051 Inconsistent accessibility: parameter type 'IInventoryServices' is less accessible than method 'InventoryController.InventoryController(IInventoryServices)' InventoryService "

[@DanielDonbavand]

Sorry it's taken a while to get back to you. Is your IInventoryServices class is public? If this still doesn't fix the issue, feel free to email me with some code snippets, so I can try and help debug further. You can find my email in my KZbin profile.

[@JavierLopezPR]

@@DanielDonbavand Thank you

[@findzee]

it is very good and simple video , would love to see more on using the template and integration with EF and angular 6 front end

[@ihorbond]

Hey Daniel great tutorial just what I was looking for short and on point! Quick question: you inject service as singleton because in this example you are managing application state by yourself right? Would you inject it as scoped or transient if you had the actual database connection to store items ? If so, which one (scoped or transient) would you pick and why? Thanks

[@DanielDonbavand]

Hi Ihor, it depends what database you connecting to. If you were using something like DynamoDB, then you would register the DynamoDB client and let the client manage this for you. Let's have a look first one what both scoped and transient is and does Transient Transient lifetime services are created each time they're requested. This lifetime works best for lightweight, stateless services. Scoped Scoped lifetime services are created once per request. If you were using something like Entity Framework then the Entity Framework contexts are usually added to the service container using the scoped lifetime because web app database operations are normally scoped to the request. The default lifetime is scoped if a lifetime isn't specified by an AddDbContext overload when registering the database context. Services of a given lifetime shouldn't use a database context with a shorter lifetime than the service. Further information can be found here docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-2.2

[@squarebodyrancher]

Thanks for the tutorial. Simple and to the point instead of watching an hour long video. Does ASP.net core come with it's own form of DI framework or is something like Ninject preferred?

[@DanielDonbavand]

Thank you. Yip .net core has a dependency injection framework built in. You can use a 3rd party library if you want, I personally haven't needed to use anything other then the built in DI

[@johannneck3250]

@@DanielDonbavand When programs get bigger you probably wanna do that. You usually dont put models, repositories and all that stuff into the api. You wanna seperate your classlibs from the actual api. Using dotnet entity framework helps a lot with the depency injections tho. Also with migrations and some other stuff.

[@johannneck3250]

i also find automapping very useful in that context

[@hamidshaikh9649]

Awesome video thanks a lot.

[@vitalikdemko]

Is it realy Web API project? I thought that in a Api project all controllers must inherit from ApiController and all actions should return HttpResponseMessage instead of ActionResult

[@yarmgl1613]

an api's job is to handle data remotely, which is what is done in this video

[@metekaba6532]

Hello and thank you for this wonderful tutorial! I have a question about web API. I understood the main idea of the web api but I did not understand how an end-user can use it. In 15:13 minute you entered a URL to get the values but for an end-user it is not practical to use it. How can we convert it to a graphical user interface? Or how can we use web api in a real application? Thanks in advance!

[@reillybrown6196]

A Web API typically exists on a remote server (known as the "back-end"). You still would want to build a "front-end", which would be a web-application that makes calls to the API in order to GET or POST data. If you are new to this concept, I would suggest looking up tutorials for "full stack web applications" to better understand the relationship between front-end and back-end.

[@metekaba6532]

@@reillybrown6196 Thank you so much for your response :) Have a great day.

[@caiovinicius4749]

Thanks! you really helped me! :D

[@Scott-oe7dv]

great tutorial! question how do you get that dialog to quickly add folders / classes / interfaces etc I constantly have to right click > add then find the thing I want to add etc.

[@DanielDonbavand]

Hi Scott, I use Resharper. Resharper has a short cut alt + insert to quickly add folders / classes. If you are not using Resharper then it looks like you can add a short cut to visual studio. stackoverflow.com/questions/42230841/set-add-class-shortcut-key-in-visual-studio

[@gustavoherrera7859]

Hello Daniel, how are you? Congratulations on your video. I'm in Brisbane Australia (near to you hehe). I get confused when and why is necessary to create services and interfaces because inside controller you could add Items or get Items. I heard that creating interfaces and services are good practices but I don't know why and when I need to use. Will be really good if you send me a good answer or some documentation about that. Thanks a lot. Warm regards.

[@DanielDonbavand]

Hi Gustavo, I've just replied to your email.

[@gustavoherrera7859]

Yeah bro, thank you. I'll share your answer, maybe someone could be useful.

[@oscarcalles6559]

Thanks!!

[@wertin200]

When used your tutorial for aps.net core 2.1 project it worked, But for my aps.net core 3.0 it does not work, because the app.UseMVC(); does not work. Could you post a updated version of this tutorial?

[@SkippyTheSnake]

In Startup.cs file in the ConfigureServices method add this line. services.AddMvc(option => option.EnableEndpointRouting = false);

[@SanthanamV]

what is the use of adding scope in startup file? why we are using the scope? please explain

[@DanielDonbavand]

Hi Santhanam, .net core has an inbuilt dependency injection container. I'm registering my dependencies that I will be dependency injecting inside my application. Microsoft has a good document that explains this approach. docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-2.2 Hope this helps.

[@ankurplays5144]

I m getting a 404 page can't be found error on running the project!

[@NuNaKri]

I had the same problem! I needed to turn off the ssl certificate in postman (File -> Settings -> SSL Certificate) and my url was wrong too, because i forgot the v1 localhost:/v1/GetInventoryItems

[@McSeeMo_]

Hi! So by using the service you dont need to configure a DbContext in the StartUp ConfigureServices ?

[@pankajupadhyay8698]

DbContext is used to write the data in database, He isn't using any db rather is is storing it in memory, so if you rerun the application the data is gone.

[@Black-sz2xv]

Спасибо, друг.

[@elzein25]

All my source files are coming back miscellaneous. Any idea on how to fix this?

[@muhammadmuqeetahmed3834]

Thanks

[@nileshrathod5713]

Hi, I am trying to test the same but I am getting SSL certificate error - The server couldn't send a response: Ensure that the backend is working properly Self-signed SSL certificates are being blocked: Fix this by turning off 'SSL certificate verification' in Settings > General Proxy configured incorrectly Ensure that proxy is configured correctly in Settings > Proxy Request timeout: Change request timeout in Settings > General. Could you please suggest

[@DanielDonbavand]

Hi Nilesh, I found this stack overflow page. stackoverflow.com/questions/47806876/could-not-get-any-response-response-when-using-postman-with-subdomain Have a read through the answers and hopefully that will fix your problem :)

[@saschakruning7410]

Hi Daniel, what do I need to do to host the service in IIS? Thanks!

[@pankajupadhyay8698]

Default server is IIS so when you run the project, it automatically hosts in on the IIS.

[@sovannseung6985]

I don't see where you put the connection string. I don't understand how the data will be save too?

[@DanielDonbavand]

Hi Seung, I don't have a connection string set as I'm simulating a database by using a Dictionary to store the inventory data. This is stored in memory and once the application is closed all data will be lost. This video tutorial isn't focusing on creating and interacting with an actual database.

[@JuanMongeJ-3Dmo]

@@DanielDonbavand Hey daniel can you make a second part focusing on interaction with database, like a continuity of this tutorial. thanks!

[@DanielDonbavand]

@@JuanMongeJ-3Dmo any DB in particular??

[@JuanMongeJ-3Dmo]

@@DanielDonbavand btw nice tutorial, I was thinking maybe a SQL db but not Microsoft maybe a postgres or another opensource fb of your choosing.

[@johnpark7396]

Hey Daniel, I tried using Postman to connect with my localhost, but I continually get a "Could not get any response". I double checked to make sure that all my routes were connected properly, yet it is not connecting into Postman. Any ideas?

[@DanielDonbavand]

Is the application running? When you run the application up from visual studio, you should see a browser window open up and in the address bar should have localhost and a port number, can I confirm you are using the correct port number as well??

[@JuanMongeJ-3Dmo]

@Dane Osborne Hero!

[@christianloperadecastro4875]

Thank you. But it's hard to follow your tutorial.

[@DanielDonbavand]

Hey Christina, what parts are hard to follow?

[@eduardofernandezdiaz5264]

I'm having this exception: System.ArgumentNullException: 'Value cannot be null.' in this line at InventoryServices.cs: _inventoryItems.Add(items.ItemNane, items); Any ideas?

[@johnneeson2968]

I had exactly the same problem. Fixed by adding [FromBody] to AddInventoryItems parameter, as follows: public ActionResult AddInventoryItems([FromBody]InventoryItems items)

[@eduardofernandezdiaz5264]

@@johnneeson2968 Thanks for responding man

[@deputyVH]

I didn't find where you add code to the interface. So now I have lots of errors.

[@deputyVH]

I seem to have muddled through to a version that compiles!

[@AhsanWasim]

i have just installed visual studio 2017 but it doesnt feature asp.net core, can any1 help me what to do next

[@DanielDonbavand]

Hey Ashan, head along to dotnet.microsoft.com/download and download the. Net core SDK

[@gregpresland2724]

How did you get Visual Studio to colour unknown types in red?

[@DanielDonbavand]

Hi Greg, are you getting a squiggle red line under unknown types? I'm using resharper btw

[@gregpresland2724]

@@DanielDonbavand Yeah I am getting the red underline. That's defaulted to being present in Visual Studio. I was going through Visual Studio options looking for how to highlight unknown types/methods/etc in red like I see you have it, but not finding the option. Looks like it's ReSharper doing it, which I don't have.

[@InayetHadi]

Do you have courses for purchase on udemy for net core 2.2 or 3.0 ?

[@DanielDonbavand]

No sorry Inayet, I have a .NET Core Dynamodb on pluralsight app.pluralsight.com/library/courses/aws-dotnet-core-developing-applications-dynamodb/table-of-contents

[@yehudaknoll6256]

Hey, Nice video. Do you know how can I publish my Web Api application on IIS? I tried everything.. Nothing goes well

[@DanielDonbavand]

Hi, while you can do this, can I ask why you want to use Windows over Linux for publishing and running your .NET Core application?

[@danielvergara6990]

@@DanielDonbavandhi i need to publish this proyect in a windows server, but i don´t know how

[@DanielDonbavand]

Hi Daniel, Have you had a look at the following... docs.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/?view=aspnetcore-2.2 or stackify.com/how-to-deploy-asp-net-core-to-iis/ I'm not really clued up on hosting .net core applications on a windows box sorry, as I host my .NET Core applications on Linux.

[@weanichsanchol7876]

What will happen if I don't do an Interface in inventory service?

[@DanielDonbavand]

Hi Weanich, by not creating an IInventoryService interface, you won't be able to use dependency injection. So you would have to 'new' up the InventoryService class. You should try deleting it, run the application and see what happens.

[@weanichsanchol7876]

Hi Daniel, I try deleting it and now I see the application cannot running because I think the service object has not been initialized so I comment the constructor that take 1 parameters (IItemService ItemService) and use constructor that take 0 parameter instead, then I have to 'new' the ItemService like you told me. I think if I use Interface I can initiate it in startup.cs in part of services.AddSingleton as you do in your video and the service will initiate when app has been started. Therefore, In all code that have constructor that take service parameter will initiate and can use it in their context. In this case If I can initiate service in startup.cs so I can initiate it from another source (e.g. test script) and change the interface to the implementation of the interface like mockup class for testing right? and it is a reason that why I have to use the interface instead of 'new', or there are another reason that we use the interface? Could you please tell me? thank you.

[@DanielDonbavand]

Yip, sounds about right. Have a look at this page from Microsoft, it might help in understanding the concept a bit more. docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-2.1

[@everyonesview]

@@DanielDonbavand I don't agree with you saying 'by not creating an IInventoryService, you won't be able to use dependency injection'. What it is, is we create interfaces to make applications easier to unit test by mock these interfaces. One can always register a concrete type in the Startup class (in this case as services.AddScoped()) and inject it into a Controller if they so wish, and it will still work. It only becomes harder to mock these concrete types for unit testing. By the way, aren't Services supposed to be Scoped instead of being Singletons?

[@DanielDonbavand]

Hi @@everyonesview, thanks for taking the time to comment. You are right, we could just register the InventoryService concrete class and dependency inject it inside our application. I was more replying to the comment from Weanich about "What will happen if I don't do an Interface in inventory service" saying that it would break DI in this case. I should have made my comment a lot clearer, stating what you have mentioned above, but I wanted to try and let Weanich do the research and get to the answer himself, I believe in his second comment he did just that, stating that creating an interface will help with testing. I also didn't want to highlight to much the ability to inject the concrete classes all over the show as I don't believe that was what DI was designed to achieve. Looking at the Dependency inversion principle en.wikipedia.org/wiki/SOLID "one should "depend upon abstractions, [not] concretions" In terms of the scoped vs singleton question. I'm interested to hear why you would use scoped over singleton. If we change to using scoped in this demo inventory application, then stored items inside the dictionary would you expect to get any of the items back that we add?

[@harwindersingh6682]

nice video also create for video .net core 2.1 web api with angular 6

[@INGLESOO]

now how i conect to the database?

[@DanielDonbavand]

Hi Sebastianbb, I don't currently have any videos showing how to connect to a SQL database. I do have videos on how to connect and use a NoSQL database 'DynamoDB' kzbin.info/aero/PLzoe6wiIwq3781gOtoXpYRBpHfxAGO7F7

[@HaiChu2412]

A bit too fast

[@JMV0910]

💚❣️💖

[@JMV0910]

Anna has a baby💚❣️💖

[@dewayoga3192]

Why so complicated

[@DanielDonbavand]

Any parts in particular, or the whole thing? Do you have any experience with c# and object oriented programming?

[@JustasVilimas]

This is very sad... Why would you even do an API tutorial with a verb in the route without even mention to never actually do it? :-(

[@DanielDonbavand]

Hi Justas, can you expand on that comment a little more? Are you talking about the v1 in the route?

[@JustasVilimas]

@@DanielDonbavand No, not v1. Adding Get and other verbs is the evil. :-) Just google for "REST API design principles and best practices" and you'll see...

[@kristineguardian]

@@DanielDonbavand I think this is what Sir Justas refer hackernoon.com/restful-api-design-step-by-step-guide-2f2c9f9fcdbf

[@Rob-777]

that accent..

[@user-qj4ru6qp1q]

1st comment! ^_^

[@JMV0910]

💚❣️💖