Problem is that the context is being disposed before I can access it. How to resolve EF Core interceptors from the dependency injection container. See here the interface IEnvioEmail and the class EnviarEmail : This class "simulates" sending an email, I imagine you will implement a real class for this! As a result, its important that applications implement caching to ensure theyre not, in the case of managed identity, calling the token endpoint too often. Still, over time this database can get "dirty," or with "bad" data, so we have to clean and start all over again. Which gets the list of products from the ProductService. In an ASP.NET Core application, it translates to new instances being constructed for each HTTP request. Should services always return DTOs, or can they also return domain models? This is particularly handy to simulate a failure when executing low-level database operations against data such as SELECT, INSERT, UPDATE and DELETE. I'm injecting a dependency file which at the same time contains an injected DbContext. Implementing repository querying interface in EF Core DbContext Promote an existing object to be part of a package. See that you can exchange UseInMemoryDataBase() for UseSqlServer() or any other database provider, and everything is still working! Each conceptual event will have a "before" and an "after" interceptor method. EF Core Dependency Injection Internals | 1unicorn2 Supporting database-specific commands 716k 172 172 gold badges 1315 1315 silver badges 1434 1434 bronze badges. c# - How to access a (dependency-injected) service from an EF Core (3.1 That is more common than you think! When this happens EF still needs the result to continue execution. Can't you just inject your service to the caller and do your logging there? ajcvickers label. First off, we need somewhere to get the current user. However, it turns out that both the DbContext instance and its options are by default registered as scoped services. In the last article in this series, I will show you two straightforward things: first, how to use the EntityFramework Core in memory and how to invoke an injected dependency without using the class constructor! Testing: Simulate database failures using EF Core Interceptors Entity Framework Core Interceptor: Interception of database operations. This feature was introduced in EF Core 5.0. To implement connection interception, we need to create a custom interceptor and register it accordingly. Running the application, we will have the following result: The dependency injection mechanism allows us to simplify development greatly! Connect and share knowledge within a single location that is structured and easy to search. Find centralized, trusted content and collaborate around the technologies you use most. Follow edited May 13, 2020 at 4:10. marc_s. implement an adapter/interceptor class to add the marker type and then. Diagnostic listeners are not suitable for getting events from a single DbContext instance. Okay, we have a lot of things going on here, and I will explain: In the controller constructor we are receiving some objects by injection: All are assigned to variables within the controller. We then briefly discussed the lifetime scopes we can use for both our interceptors and their dependencies without running into issues. Volo.Abp.EntityFrameworkCore is the main NuGet package for the EF Core integration. As per this question and discussion in comments, this is possible, but not recommended. EF6 - Interceptor in EF6 Tutorial - Entity Framework IHttpContextAccessor allows us to access the ASP.NET Core Http Context anywhere it is injected, and IEnvioEmail is an example class that I created to simulate the sending of email. Edit: the scenario is actually more complex than a simple logger. We will create ClientController.cs, which will have two actions: Get() to bring all customers and Email() to "simulate" the sending of email. Powered by Jekyll By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. ASP.NET Core: Dependency Injection for DB CF Migrations, Dependency Injection error: Unable to resolve service for type while attempting to activate, while class is registered. We'll just add the GlobalInterceptor class registration to our DI container which will make it resolved in the constructor of GlobalListener and we can use it to add our interceptor to subscription. Or it is simply injected into another class, which is even more common! It seems right now the controller which created the model needs to track this explicitly, whereas if models supported DI they would be able to capture the DbContext in the constructor. Download here; Basic knowledge of Entity . This means we have to resolve the GlobalListener instance to be able to call this method and put our interceptor into action. Why does sending via a UdpClient cause subsequent receiving to fail? For this example we are going to create an ASP.NET Core WebAPI project. Dependency Injection in EF Core 1.1 | 1unicorn2 . The first of these was covered in a previous post. For example, a database interceptor could be used to log SQL, but this is better handled by one of the mechanisms tailored to logging. A better way of resolving EF Core interceptors with dependency injection Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Entity Framework Core | Documentation Center | ABP.IO and GitHub Pages Additional events were introduced in EF Core 5.0. *Typically Microsoft.Extensions.Logging is configured per-application via dependency injection. you should project out further, I think this will depend on how your application is structured. How do I update the GUI from another thread? The object of 'DbContext' class through Dependency Injection. Let's create a new class EFConnectionInterceptor that implements DbConnectionInterceptor class which is available in Z.EntityFramework.Extensions.EFCore. EF Core interceptors enable interception, modification, and/or suppression of EF Core operations. Solution. However, when using their synchronous counterparts, the synchronous ConnectionOpening method will be called internally. this way your model stays clean, and so does your command/query, but you can inject whatever you need in the middleware. Inversion of Control vs Dependency Injection. But use with care, as everything in excess is harmful! . 6. Register the Azure Identity-based token provider, // 3. When I write unit tests, I create an InMemory() context, and in the real application, I use a database! These discussions have already generated improvements in EF Core, such as WithNoLock(). Entity Framework Core (EF Core) interceptors enable interception, modification, and/or suppression of EF Core operations. User access HomeController. What is Command Interception in EF Extensions (EFE) This is best done by overriding the existing component and added this overridding version to EF via dependency injection. IDbCommandInterceptor - an interface which can be used to intercept database commands and modify them if required. I didnt realise this in the first project I introduced interceptors in simply because this code base was consistently using asynchronous methods of the DbContext. Command interception requires the following steps: Creating a subclass of the abstract DbCommandInterceptor class in EF. This feature is very valuable for unit tests, and I really hope you are writing tests! An app with two databases like mine can easily lose track of this lineage. In previous non-core versions of Entity Framework (EF), it was possible to intercept calls to and from the database, but it's wasn't a feature many would classify under "first-class support". Resolve the interceptor from the service provider, // 2. Events are simpler than interceptors and allow more flexible registration. To do this, open the Tools / Library Package Manager / Package Manager Console menu and then type the command below: PM> Install-Package EntityFramework. Interceptors are different from logging and . Then, we had a look at a solution to resolve interceptors from the ASP.NET Core dependency injection container. The high-level goal for the interception feature is to allow external code to observe and potentially intercept EF operations. We use RequestServices.GetServices() which basically "asks" for the dependency injector to "give" us the object corresponding to the IEnvioEmail interface. Imagine that you develop using a "development" database or even local on your machine, which is perfectly normal. Going from engineer to entrepreneur takes more than just good code (Ep. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. ASP.NET Core Dependency Injection: What is the IServiceCollection Simple logging with Entity Framework Core 5 and 'LogTo' (like Database Multiple database access from the same DbContext in Entity Framework Core 5. EF Core interceptors enable interception, modification, and/or suppression of EF Core operations. To use this method, you will need the following Entity packages: The InMemory package allows you to have a database in memory. DbCommandInterceptor - this is an abstract class which can be used instead of interface. Situations where EF Core In-Memory is useful; What is Dependency Injection; Use in-memory provider and dependency injection in .net core console application; What you should know / have. If this is not a problem for you, then we can inject to our entities like this: This is generally frowned upon, and normally we would inject those services into the caller (e.g. "/> Special thanks to my friend Rafael Almeida, with whom I "argue" frequently about EntityFramework!!! In order to be able to do your joins on tables or views in different databases you need to do it in the same connection instance which is bound to DbContext . If you need additional logging beyond what EF Core components already produce, you will need to override EF Core's lower-level components. The image below (click for a larger view in a new window) shows the steps involved. by @todthomson. No messing around with the internal service provider, no need to create an extension that is meant to be leveraged by third-party providers. In our project, we need to send an email, and the email class is in dependency injection (we set it up in Startup.cs), but we don't put it in the controller constructor because it's a little-used method, and in this case, it doesn't justify it hypothetically! Accessing multiple databases from the same DbContext in EF Core While going through the different overloads of the AddDbContext method, I realised that several of them were accepting a delegate parameter that was given an instance of IServiceProvider. So, I decided to complement this series by showing an extremely useful feature of EF Core, which is the in-memory database. I while ago I wrote an article on how toAccess multiple databases from the same DbContext in EF Core which relies on interceptors to mutate the SQL query diring execution. The implication is that should we need it, our interceptors can be registered as scoped services without causing a captive dependency problem, which is when a service with a longer lifetime, like a singleton, takes a dependency on a service with a shorter lifetime, like a scoped service. This post is aimed at provider writers and people who may want to contribute to the EF source code. EF Core exposes .NET events to act as callbacks when certain things happen in the EF Core code. The first thing we will do is create a class (table) and the context. Would a bicycle pump work underwater, with its air-input being above water? How can these services be resolved from within a model, such as when I want to log something from the model? Each of these is tailored to different situations, and it is important to select the best mechanism for the task in hand, even when multiple mechanisms could work. Add IDbCommandInterceptor or similar to allow injecting custom - GitHub Entity Framework Core 5 Interceptors | Khalid Abuhakmeh Doing this requires configuring a custom service provider for EF to use internally. Use one of the overload of AddDbContext that takes a parameter of type Action, // 3. You are taking an object that is already created and bringing it to the variable email. That is very cool because you are "injecting" an object by hand. So we are injecting an Entity Framework context into our project through AddDbContext(), and also two other classes: IHttpContextAccessor and IsendEmail (IEnvioEmail), using Singleton and Scoped, which I showed in the previous article. Using Azure Identity with Azure SQL, Graph, and Entity Framework Interceptors are different from logging and diagnostics in that they allow modification or suppression of the operation being intercepted. How to Use Microsoft.EntityFrameworkCore.Sqlite Provider. To use SQLite database provider, the first step is to install Microsoft.EntityFrameworkCore.Sqlite NuGet package. Dbcontext pooling ef core - glzt.tytanpack.pl EF Core fully integrates with Microsoft.Extensions.Logging and this form of logging is used by default for ASP.NET Core applications. For example: This concept is similar to Database.Log in EF6. In this post, I wanted to take a deeper look at the first concept from the Microsoft . So let's go to the methods that interest us. Consider the following controller action method. How to resolve EF Core interceptors from the dependency injection container. Adding the Entity Framework Code First: After creating the project, we will add the Entity Framework through NuGet. Simple logging or Microsoft.Extensions.Logging are better choices for logging. In EF Core , the DbContext has a virtual method called. Does a beard adversely affect playing the violin or viola? Then think that you can keep an entire database in memory, performing the same operations that you would do in the typical database, but without saving anything anywhere except in the memory. Using Dependency Injection with Entity Framework DbContext - .NET Blog For the GlobalListener class, we do not want to instantiate interceptor the way we did, plus it would me much more difficult now when we got rid of parameterless constructor or resolve the services prior to calling constructor from the GlobalListener class. Entity Framework Core 5 Interceptors. In this tutorial I will teach you how to use the Dependency Injection method in Entity Framework Core. Entity Framework Core (EF Core) contains several mechanisms for generating logs, responding to events, and obtaining diagnostics. Injecting the DbContext like this is often considered an anti-pattern since it couples your entity types directly to EF Core. Was Gandalf on Middle-earth in the Second Age? After introducing an AAD authentication interceptor in another project, I found that the ConnectionOpeningAsync method wasnt always invoked by EF Core. When the Littlewood-Richardson rule gives only irreducibles? Can plants use Light from Aurora Borealis to Photosynthesize? 14.5k 13 13 gold badges 71 71 silver badges 129 129 bronze badges. Just really simple, straightforward code. Zane Claes Zane Claes. I while ago I wrote an article on how to Access multiple databases from the same DbContext in EF Core which relies on interceptors to mutate the SQL query diring execution. The main strength of Azure Identity is that it's integrated with all the new Azure SDK client libraries that support Azure Active Directory authentication, and provides a consistent authentication API. For ASP.NET Core we have to add querying interface and class to dependency injection. Interception in Entity Framework Core | by Ashish Patel - Medium Create Interceptor. Why is there a fake knife on the rack at the end of Knives Out (2019)? .NET, .NET CORE, Entity Framework Core. In this post we will look at some of the internal details. But why so useful? Microsoft.Extensions.Logging is an extensible logging mechanism with plug-in providers for many common logging systems. A previous post gave an overview of how dependency injection is used internally by EF Core, and how applications might interact with this. Resolving instances with ASP.NET Core DI from within ConfigureServices, ASP.Net Core Call a controller from another controller. EF Core - Database Auditing with "UpdatedBy" - Ryan Southgate's Blog In the previous post mentioned in the introduction and the code snippet above, we define an EF Core interceptor that only overrides the ConnectionOpeningAsync method. Stack Overflow for Teams is moving to its own domain! container can be used to create DbContext instances. Thats great news, as it means we can have access to the application service provider while configuring the DbContext options. by @mdo with modifications Being forced to do the name localization explicitly from outside the model would be extremely repetitive and burdensome, especially once this example was scaled out to the scope of my app.