Get started with the PostgreSQL Entity Framework Core integrations

PostgreSQL is a powerful, open source object-relational database system with many years of active development that has earned it a strong reputation for reliability, feature robustness, and performance. The Aspire PostgreSQL Entity Framework Core (EF Core) integration provides a way to connect to existing PostgreSQL databases, or create new instances from the docker.io/library/postgres container image.

In this introduction, you'll see how to install and use the Aspire PostgreSQL Entity Framework Core integrations in a simple configuration. The same hosting integration is used with both the EF Core and the non-EF Core client integrations. If you already have this knowledge, see PostgreSQL Hosting integration and PostgreSQL EF Core client integration for full reference details.

Set up hosting integration

To begin, install the Aspire PostgreSQL Hosting integration in your Aspire AppHost project. This integration allows you to create and manage PostgreSQL database instances from your Aspire hosting projects:

dotnet add package Aspire.Hosting.PostgreSQL

Next, in the AppHost project, create instances of PostgreSQL server and database resources, then pass the database to the consuming client projects:

var builder = DistributedApplication.CreateBuilder(args);
  
var postgres = builder.AddPostgres("postgres");
var postgresdb = postgres.AddDatabase("postgresdb");
  
var exampleProject = builder.AddProject<Projects.ExampleProject>("apiservice")
                            .WaitFor(postgresdb)
                            .WithReference(postgresdb);

Use the integration in client projects

Now that the hosting integration is ready, the next step is to install and configure the EF Core client integration in any projects that need to use it.

Set up client projects

In each of these consuming client projects, install the Aspire PostgreSQL EF Core client integration:

dotnet add package Aspire.Npgsql.EntityFrameworkCore.PostgreSQL

In the Program.cs file of your client-consuming project, call the AddNpgsqlDbContext extension method on any IHostApplicationBuilder to register your DbContext subclass for use through the dependency injection container. The method takes a connection name parameter.

builder.AddNpgsqlDbContext<MyDbContext>(connectionName: "postgresdb");

Use injected PostgreSQL properties

In the AppHost, when you used the WithReference method to pass a PostgreSQL database resource to a consuming client project, Aspire injects several configuration properties that you can use in the consuming project.

Aspire exposes each property as an environment variable named [RESOURCE]_[PROPERTY]. For instance, the Host property of a resource called postgresdb becomes POSTGRESDB_HOST.

Use the GetValue() method to obtain these environment variables in consuming projects:

string hostname = builder.Configuration.GetValue<string>("POSTGRESDB_HOST");
string databasePort = builder.Configuration.GetValue<string>("POSTGRESDB_PORT");
string databaseName = builder.Configuration.GetValue<string>("POSTGRESDB_DATABASENAME");

Use PostgreSQL resources in client code

Now that you've added the DbContext to the builder in the consuming project, you can use the PostgreSQL resource to get and store data. Get the DbContext instance using dependency injection. For example, to retrieve your database context object from an example service define it as a constructor parameter and ensure the ExampleService class is registered with the dependency injection container:

public class ExampleService(MyDbContext context)
{
    // Use context to interact with the database...
}

Having obtained the database context, you can work with the PostgreSQL database as you would in any other C# application using EF Core.

Next steps

Now that you have an Aspire app with PostgreSQL EF Core integrations up and running, you can use the following reference documents to learn how to configure and interact with the PostgreSQL resources: