Clean Code with Entity Framework Core | Brendan Richards

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00:00:00 - Introduction
00:03:23 - Introducing EF Core
00:17:44 - Basic Usage
00:31:04 - Clean Architecture
01:17:53 - Testing
01:20:18 - EF Core Performance
01:33:54 - What's New
01:43:28 - Conclusion and Questions
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Object Relational Mappers like EF Core exist to take the drudgery out of getting your Object-Orientated C# code to talk to a relational database. Opinions on this vary from "ORMs are the Vietnam of Computer Science" to "If you write data access code, you are stealing from your client".
Like any powerful tool, EF Core can help you a great deal when used carefully, or cause chaos when thrown blindly at your codebase.
This talk covers:
- An introduction to the primary features of EF Core
- How to use EF Core with clean code principles
- What's new in EF Core
- Techniques to monitor performance and what to do about badly behaved queries.
About the Speaker ↴
Throughout his career, Brendan has been a big user and proponent of Open Source software. This has been applied to a broad variety of web-based programming projects spanning the last 17 years. Brendan has worked with an eclectic mix of languages, platforms and technologies including .Net, Java, PHP, Ruby and Perl across both Unix/Linux and Microsoft Windows platforms. This gives Brendan some unique perspectives on how different teams & platforms have tackled similar problems.
Since joining SSW in 2012, Brendan has been delivering great solutions on the .NET stack for his clients. He is also been sharing his knowledge and experience with the wider developer community by speaking at Conferences such as NDC and DDD as well as .NET User Groups
Some of his favourite things include:
- .NET Core - especially the cross-platform support for Linux
- Typescript and moden client side development with Angular CLI & ngrx
- Elastic Search
- Clean Architecture
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16 июл 2024

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Комментарии : 64

@SSWTV 4 года назад

The source code that Brendan used to create code samples for this talk is here ➡ github.com/brendan-ssw/Northwind-EFCore3 Camilla Rosa SSW TV | Videos for developers, by developers ssw.com.au

@chientran5554 3 года назад

fsdf4

@Kay-hx8xb 4 года назад

Clean architecture at 32:28

@vekzdran 4 года назад

Nailing it every single time Brendan! Love the energy level and focus you keep even when interrupted. Congrats, keep the great work!

@timmyers9798 3 года назад

Just watched this now and I have to say that as I'm just learning EF core it's one of the best talks I have every seen on the topic. Thanks SSW.

@TreeLuvBurdpu 4 года назад

Best line: "The secret-sauce of spaghetti code is dependencies". Could we maybe call it dependency pomodoro or dependency fettuccine?

@brianwells990 4 года назад

Outstanding presentation! Thank you so much for sharing your thoughts.

@camilla_rosa 4 года назад

Great presentation, Brendan!

@Keiktu 3 года назад

This is pure gold!!! Thank you!

@JohnPeter-yf5jf 4 года назад

Thank you for this! I love that project of his.

@brendanrichards1722 4 года назад

yes, Jason's Northwind Traders project is now pretty much the base of any talk I do. And this post (www.codingflow.net/building-single-page-applications-on-asp-net-core-2-2/) has been my "file->newProject" walkthrough on a couple of projects recently - saving a lot of time!

@wpaap 4 года назад

Great stuff. Anyone who likes this should also watch the video from Jason Taylor on NDC Sydney 2019 where he demo's a similar approach using auto-mapper. The only thing I do not like is ApplyFilters() as a method to apply all filters at once. A cleaner way would be to have methods that return a queryble per filter and apply those after one another.

@jerryluo4335 4 года назад

Great presentation. I will use it in my project.

@bilbobaggins8953 4 года назад

at 30:50 setting the state explicitly to modified is to show that the entity can be passed to the method without being tracked (it can be retrieved with AsNoTracking) and it will be saved to the db regardless.

@antevuletic3393 4 года назад

Great presentation. I think it would be nicer for the speaker if there were question segments, so there is no interruptions to the presentation flow.

@herbertmilhomme 4 года назад

It helps having information grouped together because it increases understanding and clarity before stacking layers of data on top a foundation of confusion. Just like in classroom where teacher makes sure everyone understands before moving on, this is helpful for some us that get lost along the way.

@Keiktu 3 года назад

I've been using repo pattern for quite a while, 1st time I hear about CQRS... seems really good.

@GeminiLearning 4 года назад

Very informative video on under the hood mechanics of EF. I'm a great fun of EF Code First model. Could you kindly do a video on how to write and use SQL Server stored procedures using EF code First. Also how to use EF with advanced data types in SQL Server ie Spatial and JSON data types

@deepakpandey9406 4 года назад

1:12:26 *FromSqlRaw* : Here you can pass the name of Stored procedure along with the parameters.

@leakyabstraction 3 года назад

DbContext + vertical slicing (as opposed to CQRS, which is most often a misnomer when people discuss their use of MediatR) indeed can be a sufficient replacement for the classical repository pattern, because the vertical slices (with e.g. request handlers via MediatR*) are a good place to store query logic that pertains to individual operations. But there are still some pretty general cross-cutting-like concerns that make the repositories (+ UoW, because saving in a repository is ugh) a useful abstraction. For example defining default queries, defining includes for different queries, and adding paging/filtering/ordering logic. Plus I think it also has some limited inherent value in itself that EF Core is abstracted, and your application core has zero direct references to it (provided that you also avoid using DataAnnotation attributes on domain models; although those aren't strictly EFCore-specific). *One of my pet peeves being that MediatR is also a misnomer, because what it does is essentially commanding, i.e. encapsulating operations/requests in commands and corresponding handlers, with a questionable service locator on top; instead of 'mediating' in the classical Mediator design pattern sense. It's still a great piece of software, of course. Thanks for the great talk btw! Definitely one of the most informative and tightly packed talks I've seen on the subject.

@loam 4 года назад

In the project I worked, the Repository pattern layer didn't grew up to become business logic; there was another layer, we called it Services, and that layer had some fancy logic and [UnitOfWork] attributes marked methods, which could call and use several methods from different Repositories, and all the sql requests would be done in one transaction.

@brendanrichards1722 4 года назад

Sounds like a great solution. I've done a very similar thing and called it the "Business Logic" layer. All works great as long as you keep the right code in the right layers. A good rule of thumb here is that as soon as two repositories are involved, that's when it need to go into another layer with some form of unit-of-work. Avoid makling one repository call another repository - I've never seen this end well!

@pomni8696 4 года назад

That's exactly what Ive constructed in the project I'm in now. We need complex logics to represent domain rules and we want to consider transactional contexts between it. So domain service contains unit of work to ne injected as default. It just ended up like this form naturally.

@jakubbarczyk477 4 года назад

I personally use repositories interface above EF core layer because in early stages of products I prefer to use rather file system over database. Also it's easier to replace EF Core to another approch for managing data

@rentefald 4 года назад

That is just stupid.

@leakyabstraction 3 года назад

At 5:00 that schema is typically a one-to-many relationship. :P Since you can insert multiple skills for the same PersonId foreign key (unless we explicitly add a Unique constraint besides the foreign key constraint). Strict one-to-one (well, actually one-to-zero-or-one, because it's technically impossible to enforce 1-to-1) would be using the PersonId as the primary key in the Skills table, which would constrain us to store only a single skill per PersonId. I know I'm nitpicking. :D Edit: Ah okay, 30 seconds later you mention it. That's why I should always watch the whole video before commenting. Which I never do of course.

@lucianbumb6690 4 года назад

Very good talk, very useful ! thank you It was too quick for me so I reduce the speed of the video to 0.75, then it was even more interesting :) ... it sounds like a drunk person :)

@umair_me 4 года назад

0.5 speed makes the voice even more funny :D

@TheMessixaviniesta 4 года назад

That's very bad for productivity, I usually do the opposite and speed up videos.

@dymonkhlopov86 3 года назад

how is it clean when your application layer depends on persistence layer (there is reference to EntityFrameworkCore)

@NiamorH 3 года назад

yeah I definitely see shortcuts here. and that's probably suitable for a very contained, small scoped service.

@nemanja.djordjevic 4 года назад

Did you mean new object, not new class at 9:55?

@mattmarkus4868 2 года назад

1:29:25 what is the name of the lib for BulkInsert ?

@ryanconnollyatwork1356 4 года назад

Looks pretty cool. Where can I find the source code?

@SSWTV 4 года назад

Hey Ryan, pretty sure you can find it here: github.com/brendan-ssw/Northwind-EFCore3

@seephor 3 года назад

nHibernate for .NET was a mess. I don't know what you think was so great about it.

@dotnetdevni 4 года назад

Problem with that approach is if u have allot of lookups lists being consumed thru one unit of work it be very performance hungry.

@brendanrichards1722 4 года назад

One big benefit to separating out commands vs queries is also the opportunity to cache the responses from queries. serving shared lookup data from cache will always beat any db based lookup.

@ryanconnollyatwork1356 4 года назад

FYI, the source code is located... github.com/SSWConsulting/Northwind365

@nghiemhoang1916 4 года назад

I download your repo and try to run Add-Migration, it throws this error Your target project 'Northwind.EF.WebApi' doesn't match your migrations assembly 'Northwind.EF.Persistence.MSSQL'. Either change your target project or change your migrations assembly. Change your migrations assembly by using DbContextOptionsBuilder. E.g. options.UseSqlServer(connection, b => b.MigrationsAssembly("Northwind.EF.WebApi")). By default, the migrations assembly is the assembly containing the DbContext. Change your target project to the migrations project by using the Package Manager Console's Default project drop-down list, or by executing "dotnet ef" from the directory containing the migrations project. Could you please show me details how you run your migrations?

@nghiemhoang1916 4 года назад

I found the root cause. I have to run with command Add-Migration -Project -StartupProject -Name

@brendanrichards1722 4 года назад

@@nghiemhoang1916 Yes, my proof-of-concept for setting up a project against multiple databases does make the whole migrations process much harder! I've also added the Northwind.EF.Persistence.Tools project - this is a small console project that can act as the startup assembly for running migrations. The migrations systen needs to start against a target framework - can't bootstrap with a netstandard project.

@weifengmao 4 года назад

Wait a minute, this is more or less the same material from Jason more than a year ago.

@navjotsingh1081 3 года назад

I just don’t understand what is the benefit of having the INorthWindDbContext over the top of the DbContext class....not sure what the author wanted to achieve with it...

@gds03_ 4 года назад

the URL for the repo github.com/brendan-ssw/Northwind-EFCore3

@SSWTV 4 года назад

Hi Goncalo, Thanks for getting in touch, how can we help? I've added Brendan to the loop if it is related to his GitHub. Penny ssw.com.au

@AhmetYigiter 4 года назад

Thank you 🙏 but please change your microphone!

@reg-net8956 3 года назад

No VB.Net, No views!

@RowlandOConnor 4 года назад

After 20 years of using ORM's, I can say that they suck for performance and maintainability. ADO.net abstracted by a repository pattern is faster, easier to manage and doesn't break every 5 minutes on package updates (as in EF).

@Kefir0 4 года назад

Bullshit, after 15 years of using ORMs, I can say that they have come a long way, and EF Core is awesome right now. Performance is fine for most apps, and every other aspect is better than raw ADO.NET.

@RowlandOConnor 4 года назад

@@Kefir0 Respect your view but, based on my observations, disagree.

@SayWhaaaaaaaaaaaaaaaaaaaaaaat 3 года назад

EF is garbage because you cant write raw sql if sql query doesn't return ALL fields of table. if you have 20 columns and you only one to select 1 column -you cant... EF is created to be slow and big

@leakyabstraction 3 года назад

"lightweight", hmm. :) I'd think something like Dapper is lightweight.

@senthilramalingam9500 4 года назад

Dapper is far far better than the EF Core. You will have a full control to solve the impediments.

@Sttuey 4 года назад

Woo, look how clean my ORM code is, it's amazing. Now let's deploy it into production and watch everything slowly grind to a halt as the bullcrap ORM sql written by clueless .net coders drags my poor database server to its knees 😂😂😂

@AlexDresko 4 года назад

Have fun in your misguided world.

@uncommonbg 4 года назад

So you are saying every SQL query you or anybody in your team has written is absolutely perfect and optimized?

@Kefir0 4 года назад

If your coders are clueless, they will write bad queries anyway, be it LINQ or SQL. At least with LINQ there is less chance for sql injection vulnerabilities. Hire good coders and their queries will be good, no matter ORM or not.

@NiamorH 3 года назад

@@Kefir0 while OP being provocative, I can concede that translating plain sql to EF Linq equivalent is sometimes not an easy task.

@SayWhaaaaaaaaaaaaaaaaaaaaaaat 3 года назад

EF is GARBAGE!!! if key is LONG you CANT use this XXX.Find(1)...will get error..because you must use XXX.Find((long)1). NEVER ever seen such problem when you cant use int in LONG property.