What are record types in C# and how they ACTUALLY work

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Күн бұрын

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Hello everybody I'm Nick and in this video I will talk about the record type that was added in C# 9. Records are great and they have many usecases but in this video we are going to focus on their features and also how they made their way into the language without having to change the runtime.
Intro - 0:00
Record features - 1:37
What records are behind the scenes - 10:12
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#csharp #dotnet #records

Пікірлер: 152

@ExpensivePizza 2 жыл бұрын

I've been coding in C# for 20 years and I still learn a lot from your KZfaq channel. Thanks Nick!

@PaulSinnema 2 жыл бұрын

Me too. Thanks Nick.

@Alequez97 2 жыл бұрын

Are you that guy that bough pizza for 10k bitcoins?

@ExpensivePizza 2 жыл бұрын

@@Alequez97 Laszlo Hanyecz paid 10,000 Bitcoins in 2010 for two large pizzas. Those pizzas now only cost 0.00135 Bitcoin. I'm not the guy, but I know the story ;)

@zenluiz 2 жыл бұрын

Same here

@prorakesh Жыл бұрын

15 here guy here.. when I see these features I realize what all I am missing. Great explanation in limited time. kudos.

@buriedstpatrick2294 2 жыл бұрын

Records also serialize/deserialze very neatly. One issue I've had with using classes for this is the need for an empty constructor for HTTP request bodies. Essentially forcing the objects to be mutable. But with records you can have the best of both worlds. As in, enforce immutability with specific constructors while allowing for JSON serialization.

@AlFasGD 2 жыл бұрын

More specifically, records use the synthesis part of the lowering process. All these members are called synthesized, and it's common among the most widely adopted features of the language, including auto-properties. The compiler synthesizes those members for our convenience of not needing to write the same boilerplate code everywhere. Then, those synthesized parts are lowered into the more primitive constructs the compiler would like to care about when compiling into IL. Examples of other synthesized members include: - async/await methods (using iterators) - IEnumerable methods using yield (yield iterators) - records, as shown - auto-properties (using the backing field)

@damiank6566 11 ай бұрын

Been writing a C# for 5+ years now but I'm still impressed how Nick knows all these syntax tricks. For example, I never used "with" keyword, seems awesome though! Not mentioning the record types itself

@mattymattffs 16 күн бұрын

With keyword is a trap

@mabakay 2 жыл бұрын

14:07 "From record to this monster..." Like it! ;-)

@responsibleparty 2 жыл бұрын

Thank you for this. I really didn't understand why record was added. Now, I see that is provided additional features but not in a more efficient way. So I would only use it if I really wanted the syntactic sugar it provides.

@barwalgayatri4655 Жыл бұрын

One of the Best Info

@mohamedelhakim5966 2 жыл бұрын

Really enjoyed that video

@rikk0011 2 жыл бұрын

I started using it just recently, thank for the video, this explains some of my questions!

@odeyjoshuasunday998 10 ай бұрын

using with was amazing, you're a genius

@TheBdc884 2 жыл бұрын

I am a senior backend developer that has 80% or more of personal experience on Java. I have had a freelance job NetCore doing some basic projects on it and decided to take a full time job on c# and increase my knowledge. Your videos have been both very educative and surprisingly interesting and amusing! I had to thank you Nick. Happy new year! Hop you will keep on delivering this great quality content!

@nickchapsas 2 жыл бұрын

Happy new year! See you in 2022

@MrJeeoSoft 2 жыл бұрын

I was convinced that record types were structures. Now it's more clear. Thanks for the video Nick!

@Krokoklemmee 2 жыл бұрын

@@Qrzychu92 that's not how structs work in C#, nick actually also has a video about that

@diadetediotedio6918 Жыл бұрын

@@Krokoklemmee It literaly is for the most

@aliengarden 2 жыл бұрын

I haven't had this much fun looking at code in a while. Sublime video!

@HamzaKhan-zd6qy Жыл бұрын

Very good and helpful.......

@adabsurdum7011 2 жыл бұрын

Thank you for your content. Helps me a lot with further training.

@salarkazazi7584 2 жыл бұрын

One of most worthwhile channels to visit. Thank you so much.

@MrAndrei4777 2 жыл бұрын

Very detailed as always, thanks!

@infinityminuszero 2 жыл бұрын

Dammit man! You taught so much in 15 minutes. Especially learning of sharplab was amazing for me. Thanks for your work!

@poniatowskimaximilian8618 2 жыл бұрын

I knew that there is one man on the internet who can answer my questions, so I wrote "Nick Chapsas Records" in the search bar and I didn't get disappointed ! Thank you for so many contents on so many details/subjects !

@CeleChaudary 2 жыл бұрын

Hi Nick, I'm from Venezuela, and one of the things for that I watch your videos is because I can totally understand you even though english isn't my native language.

@artursabirov8021 2 жыл бұрын

Hi, Nick! I wanna thank you for your videos, when I watch it then I learn English and .Net in the same time

@NameSurname-zm7gl 2 жыл бұрын

Ok, from now number 69 is a Nick's trademark

@dyrL90 2 жыл бұрын

Great video and explanation! Thank you very much.

@abdelrhmanahmed1378 Жыл бұрын

nice video

@xavier.xiques 2 жыл бұрын

Very interesting. Thanks a lot!

@stephenwood4814 2 жыл бұрын

An excellent and lucid explanation.

@aughey 2 жыл бұрын

I recently resurrected an old project that was giving me grief. I upgraded the projects to the latest compiler and runtime sets, converted a lot of data code into records, and while not a silver bullet, the compiler generated capabilities of records relieved a lot of issues and code bloat.

@bnotorious1 2 жыл бұрын

Nice video and explanation Nick! I noticed that this type of special class record acts like a valueObject. Can you give us an example on how to use it in a real world scenario? I will be grateful.

@MidnightSt 2 жыл бұрын

real world scenario? to represent rows in your DB ORM framework. or more generally, for DTOs, where they will be more comfortable to work with than normal classes.

@lordicemaniac 2 жыл бұрын

can you use that $() method on any object? or is it usable only in lowered code? can anything used in lowered code be used in normal code?

@nickchapsas 2 жыл бұрын

Yes it is part of the ICloneable interface

@brynarn 2 жыл бұрын

Hello Mr Nick

@BEN-ys6gu 2 жыл бұрын

Ok this is the kinda stuff that makes me want to learn C#. The newer versions have some really really good features. (I am already familiar with the language, but I want to learn more)

@Szopakleks Жыл бұрын

dude this is so good

@FernandoTakeshiSato Жыл бұрын

dude, awesome video, thanks!

@musichobbylife 7 ай бұрын

Is the layering on this Tuples -> Structs -> Records -> Classes?

@itsquick7250 2 жыл бұрын

Whats the ! (default!) in 3:02?

@artemyur7162 2 жыл бұрын

Nice content!

@yp5387 9 ай бұрын

I am still confused thought. I get what is Record type in how it is different from Class. But what is the real use case? Where do I use Records in IRL projects, and why should I use Records instead of class? In the person example, would EF work with record type? if no then I will have to create both Person class and Person record. which is duplicaiton.

@mzeeshan 2 жыл бұрын

Cool video mate!. Does that mean we can add our own custom features like Record to the C# without touching the CLR and using the lowering mechanism?

@PaulSinnema 2 жыл бұрын

At 3:05 Nick shows code with a 'default!' value for the property. What does the '!' do?

@knutharald9814 2 жыл бұрын

It prevents compiler warning about unitialized non-nullable property.

@KeithBarrowsToday 2 жыл бұрын

Way outside of the topic at hand - trying to duplicate this code line for line in VSCode - not compiling at all. Missing so many curly braces. Is this a feature of your editor?

@aah134-K 2 жыл бұрын

How to serialize? Or save in a table in db without any id? Would you add id fir the db?

@aah134-K 2 жыл бұрын

I dont know what to ask however I am trying to say would you use it as a value object? Which in definition have no id field

@CliveGregory 2 жыл бұрын

Any reason why the record type's ToString() method doesn't include quotation marks like JSON?

@nickchapsas 2 жыл бұрын

Because it isn’t json. It is just a formatted string

@clashclan4739 Жыл бұрын

what is that base..ctor() in lowered code

@rmdg82 2 жыл бұрын

Interesting video. I'm wondering what are the ideal use cases for using record instead of simple classes. Dtos? Anything else?

@liveabhishekshukla 2 жыл бұрын

Yes after seeing this video... I am also eager to know the use cases...

@nickchapsas 2 жыл бұрын

Dtos, shorthand queries or commands if you're doing CQRS with MediatR, objects that are immutable and you don't wanna bother with all the immutability implementations. The list goes on but really it is a class at the end of the day that implements what I described in the video so if you have the need for what the video showcases, then records make sense.

@tarekhaydar9795 2 жыл бұрын

The main reason is immutability, .Net reduces the amount of work to make a class immutable by inventing Records.

@thiagocustodio8177 2 жыл бұрын

I am so glad I am not the only one with this doubt

@ruekkart 2 жыл бұрын

In my team we recently started using them as commands instead of classes

@metaltyphoon 2 жыл бұрын

Didn’t the CLR have to change to support the idea of init ? Or was it already there because of F# ?

@nickchapsas 2 жыл бұрын

It didn't because it isn't a CLR thing, it is a complier limitation thing.

@EduardoAG 2 жыл бұрын

Can you use Records to serialize and deserialize json?? I mean If I change all my classes to records in my ASPNet core project it will still working?

@robertmrobo8954 2 жыл бұрын

Yes that will work. On one my projects, On the Query stack, I'm using records as my DTOs to read data from Cosmos DB. Which are serialized from Json.

@EduardoAG 2 жыл бұрын

@@robertmrobo8954 Nice. Thanks!

@syriuszb8611 2 жыл бұрын

What does the syntax of .$() do? Is this something specific for lowered code? Why not just .Clone()?

@babafemiogundipe1453 2 жыл бұрын

I think there is a clone method below that create a new instance of the class

@syriuszb8611 2 жыл бұрын

@@babafemiogundipe1453 I was refering to syntax, not method, what does $ mean?

@aliengarden 2 жыл бұрын

@@syriuszb8611 I am wondering as well. Did you figure it out?

@Hantick 2 жыл бұрын

Wondering as well

@syriuszb8611 2 жыл бұрын

@@aliengarden Sadly, no. My only guess is that it's specific for lowered code, I don't think that we can use it normally.

@marianvdovin2455 Ай бұрын

so are there any reasons not to use it all the time? As I see it is a class but with extra things for free. If you don't build high performance application then I think it is the future or what?

@barwalgayatri4655 Жыл бұрын

Please make a Video on If Interface 8.0 can Implement methods , then do we no longer need Abstraction now ??? I know the Basic difference that Abstract cant support Multiple Inheritance but Interface ca... but then whatsss the use of Abstract then ????

@arjix8738 2 жыл бұрын

So a record is like a data class? Or did I get something wrong?

@barmetler 2 жыл бұрын

How is it able to call the setter of FullName even though there isn't one? Maybe because "init" is actually a setter, and lowered code has the privilege of calling it even after initialization? I mean I know that lowered code doesn't have the same restrictions as normal code, but this kinda confuses me...

@nickchapsas 2 жыл бұрын

Init is basically an initialisation only setter. Properties are backed by readonly fields so even if there isn't a setter, you can still initialize a property in the constructor as if it had one, same as you would with a readonly field.

@barmetler 2 жыл бұрын

@@nickchapsas I know, but this isn't happening in the constructor. In the lowered code, it first clones the object, and _then_ overwrites all the to be modified fields.

@oleglivcha5041 2 жыл бұрын

Great as always,thank you very much Nick!

@mattymattffs 16 күн бұрын

It's syntactic sugar for dictionaries

@luan_maik 2 жыл бұрын

Is this a good aproach to use in Value Object?

@nickchapsas 2 жыл бұрын

Kinda. Value objects also have some extra stuff that you need to implement to have a "true" implementation but it is a good starting point

@Andrew90046zero 2 жыл бұрын

What the heck is that syntax for at 15:13 where it looks like "k__BackingField" and also "$()" ????? I'm just curious. Also, I was kinda hoping you were also going to say that Records have the ability to be more effectively cleaned up by the GC. Because it seems like they are supposed to act as value types but with references. So if you create an instance of one in a function. It may be able to automatically free up the data when the function returns. So fewer allocations?

@nickchapsas 2 жыл бұрын

Records are classes (unless it’s a record struct). They don’t have fewer allocation.

@Andrew90046zero 2 жыл бұрын

@@nickchapsas Alright cool, but what was up with that special syntax! k__BackingField

@nickchapsas 2 жыл бұрын

@@Andrew90046zero It's just how the compiler behind the scenes will generate the backing field and name it in a way that it can't clash with something that you have in your code

@Delphi80SVK 2 жыл бұрын

Nick, can you explaing why lowering code contains "DateTime" type for "DateOfBirth" when original code contains "DateOnly" type? Is there any other underthehood magic which converts DateOnly to DateTime and vice versa?

@nickchapsas 2 жыл бұрын

I actually don’t know that

@Delphi80SVK 2 жыл бұрын

@@nickchapsas maybe there are operators overwritten from/to dateonly and datetime. Or bug in that website.

@DFPercush 2 жыл бұрын

If I may provide a total guess, most date/time types may just be a 64 bit long containing a unix-style timestamp that gets calculated for the local date and time as needed. The DateOnly restriction probably just imposes a certain granularity on the values, like it can only be mod 24 hours or something.

@jhonsondoe407 2 жыл бұрын

Hey Nick. Great video, Do you think we can use record for database entities instead of classes?

@nickchapsas 2 жыл бұрын

You definitely can

@TheChlastak 2 жыл бұрын

What does this default! exclamation mark mean? 3:03

@XeZrunner 2 жыл бұрын

I would like to know that as well.

@lifelover69 2 жыл бұрын

The exclamation mark postfix is the null-forgiving operator, introduced in C# 8.

@nickchapsas 2 жыл бұрын

It means, “if I dont provide the value, set this property to the not null default value for this type”

@vivan000 2 жыл бұрын

@@nickchapsas you're very wrong and `default!` should be used with huge caution. Default for string is null, so `default!` equals to `null!`. It initializes that string property with null, but, at the same time, asks to forgive it. So the only thing it's doing is removing warning (CS8618: Non-nullable property must contain a non-null value when exiting constructor. Consider declaring the property as nullable). You will have null in that field if you don't set it, but you've asked compiler to ignore this possibility it...

@johnbleichert8322 2 жыл бұрын

Great video - thanks! Exactly what editor or development environment is that?

@igorthelight Жыл бұрын

JetBrains Rider

@pagorbunov 2 жыл бұрын

What if the record type object has a property with a reference type? How the equality check will work? Just a references equality check?

@Grimlock1979 2 жыл бұрын

It uses EqualityComparer. Default.Compare for each property. If T has not implemented any kind of equality, it will result in a reference comparison.

@pagorbunov 2 жыл бұрын

@@Grimlock1979 ty

@lollo4711 2 жыл бұрын

How do I initialize a record straight? Like: private record myData(string Name, int Age) = new("ABC",1); Couldn´t find any matching syntax to do it.

@arpanmukherjee4625 8 ай бұрын

Basically a Typed Tuple kind of thing.

@logan577 2 жыл бұрын

gud vid

@viktordoe1636 2 жыл бұрын

"I will not buy this record; it is scratched."

@_Szakal 2 жыл бұрын

On the line where u have "var nickbutOlder = nick with.." - as u shown when u compare nickbutOlder with nick it will say that they both not same reference, but i tried and removed 'with keyword doing "var nickbutOlder = nick" and in this case reference is the same (same as with classes) - why then with "with" it will be not same reference and without it will?

@nickchapsas 2 жыл бұрын

Because with will clone the object which creates a whole new object with a new reference

@vbaclasses3553 2 жыл бұрын

So record is the same as dataclasses in python?

@nickchapsas 2 жыл бұрын

Yeah, or records in Java or data classes in Kotlin or bla bla. It’s a very common feature in many languages

@vbaclasses3553 2 жыл бұрын

Nice that C# is also including it.

@shanksatutube 2 жыл бұрын

Hey Nick, what are the contents on the C# testing course?

@nickchapsas 2 жыл бұрын

You can see the full curriculum in the course’s page

@shanksatutube 2 жыл бұрын

@@nickchapsas thanks. but looks like the YTDEP2 coupon expired. bummer :(

@clashclan4739 2 жыл бұрын

why Microsoft didn't mentioned about lower nowhere in its docs?

@nickchapsas 2 жыл бұрын

I would assume because it is an implementation detail that you don’t “need” to know about

@toss2151988 2 жыл бұрын

Hello thx for video! :) Please is Dependency Injection course also for Unity/C# developers? :)

@nickchapsas 2 жыл бұрын

There is a lot of focus on ASP.NET on the course but there are a lot of non-ASP.NET stuff there too.

@programuoki-lt1465 2 жыл бұрын

kotlin data class same as record :)

@XKS99 2 жыл бұрын

I heard they are going to rename C# 11 to F#

@carstenberggreen7509 Жыл бұрын

I noticed your last part (14:30) has a datetime set to 1993, 4, 20 ? is that from a different example before the one in the beginning?

@HamishArb 2 жыл бұрын

Good video! I was also hoping that you'd touch on the init keyword and modreq/modopts. Do you have one on those?

@nickchapsas 2 жыл бұрын

I am not aware of modreq/modops. I guess it’s reading time 😀

@HamishArb 2 жыл бұрын

@@nickchapsas I look forward to the video if you make one :) they are used extensively in C++/CLI I believe (eg. const keyword on a parameter causes it)

@alexandervasylevskyi1332 7 ай бұрын

@@nickchapsas that's the answer why you know that much and willing to share. Because you learn as well, right? :) Great job Nick, I am really is amazed by quality of your videos and starting to think of making a channel myself. Reading the comments under your videos I sometimes have a lot to share but not really fan of doing it in KZfaq comments :)

@cruz1ale Жыл бұрын

10:37 mmm... sweet cheese

@scwyldspirit 2 жыл бұрын

I was working on a WASM project type yesterday, setup the models, the DbContext and setup the DI in the Program.cs file. Then I went looking for the appsettings.json file and there is none. It is looking for deps.json file that doesn't exist either. So I created one to what it is looking for and afterwards after setting up the ConnectionString and injecting it into the SqlConnection it returns an error of Key Not Found. Try it and let me know what you think...

@sahawndada 2 жыл бұрын

How to watch a Nick Chapsas video. 1. Smash the like 2.Enjoy the content 👌

@parzivallopez1272 2 жыл бұрын

came in 50 seconds. Now make a course on c# and .net core

@AhmedAbdulla2020 2 жыл бұрын

You know that the next video will be a perf comparison 😅

@robertmrobo8954 2 жыл бұрын

Looking forward to it.. 😂

@chrisfelix9065 2 жыл бұрын

This is same as data class in kotlin

@nickchapsas 2 жыл бұрын

Or data class in Python, or record in Java or

@robl39 2 жыл бұрын

If only the C# language designers created a “ref struct record class value task span” feature…

@AveN7ers Жыл бұрын

The language is definitely bloated

@pqsk 2 жыл бұрын

Keep coding...you say it in such a way that you're brainwashing us. I love it. 😆

@yasinfallah7327 2 жыл бұрын

دوست من امکانش هست که آرام تر صحبت کنی و بدون لهجه تا تمام ملیت ها متوجه بشن؟

@micalobia1515 2 жыл бұрын

His accent isn't actually very strong, for me. Personally, I think his accent actually makes him easier to understand. He could go slower though, I understand that completely, I think he goes fast so that the video isn't longer than it needs to be. It might be a good idea to change the playback speed to a lower value if that's something you can handle.

@nickchapsas 2 жыл бұрын

I prefer having some people slow me down than having a lot of people speed me up. I make content that I would like to watch myself and my biggest pet-peeve is slow content. I totally get how it is not for everyone but it is what most people find attractive to the channel, that I respect their intelligence and time

@TeddyBearItsMe 2 жыл бұрын

Omg please no One of the things I like about this channel is the speed. 15 minutes to explain what would normally take hours in a classroom. And he is perfectly understandable, no idea what kind of accent you want him to talk with :/

@Hantick 2 жыл бұрын

@@TeddyBearItsMe Nick's accent is fine. I understand almost every word.

@TimmyBraun 2 жыл бұрын

@@nickchapsas I love your fast content :), I usually still speed it up to 1.5x (occasionally 2x). Most other similar content is 2x for me