Npgsql Entity Framework Core Provider

https://www.npgsql.org/efcore/index.html
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The Npgsql provider for Entity Framework Core enables PostgreSQL database access for .NET...
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### Configure DbContext with OnConfiguring

Source: https://www.npgsql.org/efcore/index.html

Use the OnConfiguring method to set up your DbContext with Npgsql. This is simple but discouraged for production.

```csharp
public class BloggingContext : DbContext
{
    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder.UseNpgsql("<connection string>");
}

// At the point where you need to perform a database operation:
using var context = new BloggingContext();
// Use the context...
```

--------------------------------

### Configure Project File for Npgsql EF Core Provider

Source: https://www.npgsql.org/efcore/index.html

Add this dependency to your .csproj file to use the Npgsql Entity Framework Core provider.

```xml
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="8.0.4" />
  </ItemGroup>
</Project>
```

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### Scaffold EF Core Model from Existing Database

Source: https://www.npgsql.org/efcore/index.html

Use the dotnet CLI to reverse-engineer a code model from an existing PostgreSQL database.

```bash
dotnet ef dbcontext scaffold "Host=my_host;Database=my_db;Username=my_user;Password=my_pw" Npgsql.EntityFrameworkCore.PostgreSQL
```

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### Define Blog and Post Models

Source: https://www.npgsql.org/efcore/index.html

Define .NET classes to represent your database entities, such as Blog and Post.

```csharp
public class Blog
{
    public int BlogId { get; set; }
    public string Url { get; set; }

    public List<Post> Posts { get; set; }
}

public class Post
{
    public int PostId { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }

    public int BlogId { get; set; }
    public Blog Blog { get; set; }
}
```

--------------------------------

### Configure External NpgsqlDataSource for EF Core

Source: https://www.npgsql.org/efcore/index.html

Manually instantiate an NpgsqlDataSource to pass into UseNpgsql, ensuring mappings and plugins are configured at both the data source and EF provider levels.

```csharp
var dataSourceBuilder = new NpgsqlDataSourceBuilder(builder.Configuration.GetConnectionString("BloggingContext"));
dataSourceBuilder.MapEnum<Mood>();
dataSourceBuilder.UseNodaTime();
var dataSource = dataSourceBuilder.Build();

builder.Services.AddDbContextPool<BloggingContext>(opt => opt
    .UseNpgsql(dataSource, o => o
        .SetPostgresVersion(13, 0)
        .UseNodaTime()
        .MapEnum<Mood>("mood")));
```

--------------------------------

### Advanced Npgsql Configuration with UseNpgsql Options

Source: https://www.npgsql.org/efcore/index.html

Configure PostgreSQL version, NodaTime mapping, and custom enum mapping directly within UseNpgsql options.

```csharp
builder.Services.AddDbContextPool<BloggingContext>(opt =>
    opt.UseNpgsql(
        builder.Configuration.GetConnectionString("BloggingContext"),
        o => o
            .SetPostgresVersion(13, 0)
            .UseNodaTime()
            .MapEnum<Mood>("mood")));
```

--------------------------------

### Configure DbContext with PooledDbContextFactory

Source: https://www.npgsql.org/efcore/index.html

Utilize PooledDbContextFactory for efficient DbContext management, especially in high-throughput scenarios.

```csharp
var dbContextFactory = new PooledDbContextFactory<BloggingContext>(
    new DbContextOptionsBuilder<BloggingContext>()
        .UseNpgsql("<connection string>")
        .Options);

// At the point where you need to perform a database operation:
using var context = dbContextFactory.CreateDbContext();
// Use the context...
```

--------------------------------

### Configure DbContext with Dependency Injection

Source: https://www.npgsql.org/efcore/index.html

Configure the DbContext for use with a dependency injection container, common in ASP.NET applications.

```csharp
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddDbContextPool<BloggingContext>(opt => 
    opt.UseNpgsql(builder.Configuration.GetConnectionString("BloggingContext")));

public class BloggingContext(DbContextOptions<BloggingContext> options) : DbContext(options)
{
    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }
}
```

--------------------------------

### Advanced Npgsql Configuration with ConfigureDataSource

Source: https://www.npgsql.org/efcore/index.html

Use ConfigureDataSource to access and configure the lower-level Npgsql ADO.NET provider options.

```csharp
builder.Services.AddDbContextPool<BloggingContext>(opt =>
    opt.UseNpgsql(
        builder.Configuration.GetConnectionString("BloggingContext"),
            o => o.ConfigureDataSource(dataSourceBuilder => dataSourceBuilder.UseClientCertificate(certificate))));
```
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