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To get started with the .NET Aspire PostgreSQL Entity Framework Core client integration, install the 📦 Aspire.Npgsql.EntityFrameworkCore.PostgreSQL NuGet package in the client-consuming project, that is, the project for the application that uses the PostgreSQL client. The .NET Aspire PostgreSQL Entity Framework Core client integration registers your desired DbContext subclass instances that you can use to interact with PostgreSQL.

.NET CLI

dotnet add package Aspire.Npgsql.EntityFrameworkCore.PostgreSQL

PackageReference

<PackageReference Include="Aspire.Npgsql.EntityFrameworkCore.PostgreSQL"
                  Version="*" />

Add Npgsql database context

In the :::no-loc text="Program.cs"::: file of your client-consuming project, call the xref:Microsoft.Extensions.Hosting.AspireEFPostgreSqlExtensions.AddNpgsqlDbContext%2A extension method on any xref:Microsoft.Extensions.Hosting.IHostApplicationBuilder to register your xref:System.Data.Entity.DbContext subclass for use via the dependency injection container. The method takes a connection name parameter.

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

Tip

The connectionName parameter must match the name used when adding the PostgreSQL server resource in the app host project. For more information, see Add PostgreSQL server resource.

After adding YourDbContext to the builder, you can get the YourDbContext instance using dependency injection. For example, to retrieve your data source 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(YourDbContext context)
{
    // Use context...
}

For more information on dependency injection, see .NET dependency injection.

Enrich an Npgsql database context

You may prefer to use the standard Entity Framework method to obtain a database context and add it to the dependency injection container:

builder.Services.AddDbContext<YourDbContext>(options =>
    options.UseNpgsql(builder.Configuration.GetConnectionString("postgresdb")
        ?? throw new InvalidOperationException("Connection string 'postgresdb' not found.")));

Note

The connection string name that you pass to the xref:Microsoft.Extensions.Configuration.ConfigurationExtensions.GetConnectionString* method must match the name used when adding the PostgreSQL server resource in the app host project. For more information, see Add PostgreSQL server resource.

You have more flexibility when you create the database context in this way, for example:

  • You can reuse existing configuration code for the database context without rewriting it for .NET Aspire.
  • You can use Entity Framework Core interceptors to modify database operations.
  • You can choose not to use Entity Framework Core context pooling, which may perform better in some circumstances.

If you use this method, you can enhance the database context with .NET Aspire-style retries, health checks, logging, and telemetry features by calling the xref:Microsoft.Extensions.Hosting.AspireEFPostgreSqlExtensions.EnrichNpgsqlDbContext* method:

builder.EnrichNpgsqlDbContext<YourDbContext>(
    configureSettings: settings =>
    {
        settings.DisableRetry = false;
        settings.CommandTimeout = 30;
    });

The settings parameter is an instance of the xref:Aspire.Npgsql.EntityFrameworkCore.PostgreSQL.NpgsqlEntityFrameworkCorePostgreSQLSettings class.

Configuration

The .NET Aspire PostgreSQL Entity Framework Core integration provides multiple configuration approaches and options to meet the requirements and conventions of your project.

Use a connection string

When using a connection string from the ConnectionStrings configuration section, you provide the name of the connection string when calling the xref:Microsoft.Extensions.Hosting.AspireEFPostgreSqlExtensions.AddNpgsqlDbContext* method:

builder.AddNpgsqlDbContext<MyDbContext>("pgdb");

The connection string is retrieved from the ConnectionStrings configuration section:

{
  "ConnectionStrings": {
    "pgdb": "Host=myserver;Database=test"
  }
}

The EnrichNpgsqlDbContext won't make use of the ConnectionStrings configuration section since it expects a DbContext to be registered at the point it's called.

For more information, see the ConnectionString.

Use configuration providers

The .NET Aspire PostgreSQL Entity Framework Core integration supports xref:Microsoft.Extensions.Configuration?displayProperty=fullName. It loads the xref:Aspire.Npgsql.EntityFrameworkCore.PostgreSQL.NpgsqlEntityFrameworkCorePostgreSQLSettings from configuration files such as :::no-loc text="appsettings.json"::: by using the Aspire:Npgsql:EntityFrameworkCore:PostgreSQL key. If you have set up your configurations in the Aspire:Npgsql:EntityFrameworkCore:PostgreSQL section you can just call the method without passing any parameter.

The following example shows an :::no-loc text="appsettings.json"::: file that configures some of the available options:

{
  "Aspire": {
    "Npgsql": {
      "EntityFrameworkCore": {
        "PostgreSQL": {
          "ConnectionString": "Host=myserver;Database=postgresdb",
          "DisableHealthChecks": true,
          "DisableTracing": true
        }
      }
    }
  }
}

For the complete PostgreSQL Entity Framework Core client integration JSON schema, see Aspire.Npgsql.EntityFrameworkCore.PostgreSQL/ConfigurationSchema.json.

Use inline delegates

You can also pass the Action<NpgsqlEntityFrameworkCorePostgreSQLSettings> delegate to set up some or all the options inline, for example to set the ConnectionString:

builder.AddNpgsqlDbContext<YourDbContext>(
    "pgdb",
    static settings => settings.ConnectionString = "<YOUR CONNECTION STRING>");

Configure multiple DbContext classes

If you want to register more than one xref:Microsoft.EntityFrameworkCore.DbContext with different configuration, you can use $"Aspire:Npgsql:EntityFrameworkCore:PostgreSQL:{typeof(TContext).Name}" configuration section name. The json configuration would look like:

{
  "Aspire": {
    "Npgsql": {
      "EntityFrameworkCore": {
        "PostgreSQL": {
          "ConnectionString": "<YOUR CONNECTION STRING>",
          "DisableHealthChecks": true,
          "DisableTracing": true,
          "AnotherDbContext": {
            "ConnectionString": "<ANOTHER CONNECTION STRING>",
            "DisableTracing": false
          }
        }
      }
    }
  }
}

Then calling the xref:Microsoft.Extensions.Hosting.AspireEFPostgreSqlExtensions.AddNpgsqlDbContext%2A method with AnotherDbContext type parameter would load the settings from Aspire:Npgsql:EntityFrameworkCore:PostgreSQL:AnotherDbContext section.

builder.AddNpgsqlDbContext<AnotherDbContext>();

[!INCLUDE client-integration-health-checks]

By default, the .NET Aspire PostgreSQL Entity Framework Core integrations handles the following:

  • Adds the DbContextHealthCheck, which calls EF Core's xref:Microsoft.EntityFrameworkCore.Storage.IDatabaseCreator.CanConnectAsync%2A method. The name of the health check is the name of the TContext type.
  • Integrates with the /health HTTP endpoint, which specifies all registered health checks must pass for app to be considered ready to accept traffic

[!INCLUDE integration-observability-and-telemetry]

Logging

The .NET Aspire PostgreSQL Entity Framework Core integration uses the following Log categories:

  • Microsoft.EntityFrameworkCore.ChangeTracking
  • Microsoft.EntityFrameworkCore.Database.Command
  • Microsoft.EntityFrameworkCore.Database.Connection
  • Microsoft.EntityFrameworkCore.Database.Transaction
  • Microsoft.EntityFrameworkCore.Migrations
  • Microsoft.EntityFrameworkCore.Infrastructure
  • Microsoft.EntityFrameworkCore.Migrations
  • Microsoft.EntityFrameworkCore.Model
  • Microsoft.EntityFrameworkCore.Model.Validation
  • Microsoft.EntityFrameworkCore.Query
  • Microsoft.EntityFrameworkCore.Update

Tracing

The .NET Aspire PostgreSQL Entity Framework Core integration will emit the following tracing activities using OpenTelemetry:

  • Npgsql

Metrics

The .NET Aspire PostgreSQL Entity Framework Core integration will emit the following metrics using OpenTelemetry:

  • Microsoft.EntityFrameworkCore:

    • ec_Microsoft_EntityFrameworkCore_active_db_contexts
    • ec_Microsoft_EntityFrameworkCore_total_queries
    • ec_Microsoft_EntityFrameworkCore_queries_per_second
    • ec_Microsoft_EntityFrameworkCore_total_save_changes
    • ec_Microsoft_EntityFrameworkCore_save_changes_per_second
    • ec_Microsoft_EntityFrameworkCore_compiled_query_cache_hit_rate
    • ec_Microsoft_Entity_total_execution_strategy_operation_failures
    • ec_Microsoft_E_execution_strategy_operation_failures_per_second
    • ec_Microsoft_EntityFramew_total_optimistic_concurrency_failures
    • ec_Microsoft_EntityF_optimistic_concurrency_failures_per_second

  • Npgsql:

    • ec_Npgsql_bytes_written_per_second
    • ec_Npgsql_bytes_read_per_second
    • ec_Npgsql_commands_per_second
    • ec_Npgsql_total_commands
    • ec_Npgsql_current_commands
    • ec_Npgsql_failed_commands
    • ec_Npgsql_prepared_commands_ratio
    • ec_Npgsql_connection_pools
    • ec_Npgsql_multiplexing_average_commands_per_batch
    • ec_Npgsql_multiplexing_average_write_time_per_batch