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BifrostQL
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Connect SQL Server, Postgres, MySQL, SQLite

BifrostQL reads connection strings for SQL Server, PostgreSQL, MySQL, and SQLite, and serves the same GraphQL API over each. This page gives the package, the provider registration, the connection string shape, and a query to confirm the connection works. Every engine follows the same three steps, so switching from SQLite in development to Postgres in production changes two lines.

If you have not installed BifrostQL yet, start with getting started.

1. Install the packages

Section titled “1. Install the packages”

Every project needs BifrostQL.Server plus exactly one dialect package:

Terminal window
dotnet add package BifrostQL.Server
dotnet add package BifrostQL.SqlServer   # or BifrostQL.Ngsql / BifrostQL.MySql / BifrostQL.Sqlite

BifrostQL.Core arrives transitively. Add it explicitly only if you call Core APIs from your own code.

Database Package Underlying driver
SQL Server BifrostQL.SqlServer Microsoft.Data.SqlClient
PostgreSQL BifrostQL.Ngsql Npgsql
MySQL / MariaDB BifrostQL.MySql MySqlConnector
SQLite BifrostQL.Sqlite Microsoft.Data.Sqlite

2. Register the provider

Section titled “2. Register the provider”

Dialect packages do not register themselves. Call DbConnFactoryResolver.Register once, before the host starts, for the engine you installed. Skip it and startup throws No factory registered for provider ….

using BifrostQL.Core.Model;
using BifrostQL.Server;
using BifrostQL.SqlServer;


DbConnFactoryResolver.Register(BifrostDbProvider.SqlServer, cs => new SqlServerDbConnFactory(cs));


var builder = WebApplication.CreateBuilder(args);
builder.Services.AddBifrostQL(o => o.BindStandardConfig(builder.Configuration));


var app = builder.Build();
app.UseBifrostQL();
await app.RunAsync();

That is the whole host. UseBifrostQL mounts the GraphQL endpoint, the GraphiQL playground, and the authentication middleware.

Swap the last using and the registration line per engine:

Database Namespace Registration
SQL Server BifrostQL.SqlServer DbConnFactoryResolver.Register(BifrostDbProvider.SqlServer, cs => new SqlServerDbConnFactory(cs));
PostgreSQL BifrostQL.Ngsql DbConnFactoryResolver.Register(BifrostDbProvider.PostgreSql, cs => new PostgresDbConnFactory(cs));
MySQL BifrostQL.MySql DbConnFactoryResolver.Register(BifrostDbProvider.MySql, cs => new MySqlDbConnFactory(cs));
SQLite BifrostQL.Sqlite DbConnFactoryResolver.Register(BifrostDbProvider.Sqlite, cs => new SqliteDbConnFactory(cs));

Register more than one when a single host serves several profiles.

3. Supply the connection string

Section titled “3. Supply the connection string”

BindStandardConfig reads the connection string from ConnectionStrings:bifrost and the rest of the settings from the BifrostQL section:

{
  "ConnectionStrings": {
    "bifrost": "Server=localhost;Database=mydb;User Id=sa;Password=xxx;TrustServerCertificate=True"
  },
  "BifrostQL": {
    "Path": "/graphql",
    "Playground": "/graphiql",
    "DisableAuth": true,
    "Provider": "sqlserver"
  }
}

Connection string shapes per engine:

Database Connection string
SQL Server Server=localhost;Database=mydb;User Id=sa;Password=xxx;TrustServerCertificate=True
PostgreSQL Host=localhost;Port=5432;Database=mydb;Username=postgres;Password=xxx
MySQL Server=localhost;Port=3306;Database=mydb;User=root;Password=xxx
SQLite Data Source=app.db

TrustServerCertificate=True accepts any certificate the server presents. It suits local development. For anything else, read what accepting it costs.

Naming the provider

Section titled “Naming the provider”

BifrostQL:Provider is optional. When it is absent, BifrostQL infers the engine from the connection string, and throws rather than guessing when the string matches nothing. Set it explicitly when a string is ambiguous or when you want the failure at configuration time. Accepted names:

Engine Accepted values
SQL Server sqlserver, mssql
PostgreSQL postgresql, postgres, npgsql, pgsql
MySQL mysql, mariadb
SQLite sqlite

Authentication is on by default. "DisableAuth": true suits a first run only — see authentication and OIDC before exposing the endpoint. Without it, BindStandardConfig requires a JwtSettings section and throws when it is missing.

4. Confirm the connection

Section titled “4. Confirm the connection”
Terminal window
dotnet run

Open the playground at http://localhost:5000/graphiql. The API endpoint sits at http://localhost:5000/graphql.

Every table in the database is now a query field. Pick one and read ten rows:

{
  users(limit: 10, sort: [name_asc]) {
    data {
      userId
      name
      email
    }
  }
}

Rows come back nested inside data, and the field takes limit, offset, sort, and filter arguments. Seeing rows means the connection string, the provider registration, and the schema read all worked.

If the field names surprise you, read schema generation — BifrostQL derives GraphQL names from your table and column names.

Where the engines differ

Section titled “Where the engines differ”

The GraphQL surface is identical across all four, but the SQL underneath is not. Identifier quoting, paging syntax, string concatenation, full-text search, and upsert strategy each have a per-engine spelling. The SQL dialect reference has the capability matrix.

Next steps

Section titled “Next steps”