Fritz.InstantAPIs 0.2.0

.NET 6.0
dotnet add package Fritz.InstantAPIs --version 0.2.0
NuGet\Install-Package Fritz.InstantAPIs -Version 0.2.0
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<PackageReference Include="Fritz.InstantAPIs" Version="0.2.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Fritz.InstantAPIs --version 0.2.0
#r "nuget: Fritz.InstantAPIs, 0.2.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install Fritz.InstantAPIs as a Cake Addin
#addin nuget:?package=Fritz.InstantAPIs&version=0.2.0

// Install Fritz.InstantAPIs as a Cake Tool
#tool nuget:?package=Fritz.InstantAPIs&version=0.2.0


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This article contains two different ways to get an instant API:

  • An API based on a DbContext, it will generate the routes it needs given a database class. There are two implementations of this: Reflection and a source generator.
  • An API based on a JSON file.

DbContext based API

A proof-of-concept library that generates Minimal API endpoints for an Entity Framework context. Right now, there are two implementations of this: one that uses Reflection (this is the one currently in the NuGet package), the other uses a source generator. Let's see how both of them work.

For a given Entity Framework context, MyContext

public class MyContext : DbContext 
    public MyContext(DbContextOptions<MyContext> options) : base(options) {}

    public DbSet<Contact> Contacts => Set<Contact>();
    public DbSet<Address> Addresses => Set<Address>();


We can generate all of the standard CRUD API endpoints with the Reflection approach using this syntax in Program.cs

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddSqlite<MyContext>("Data Source=contacts.db");

var app = builder.Build();



Now we can navigate to /api/Contacts and see all of the Contacts in the database. We can filter for a specific Contact by navigating to /api/Contacts/1 to get just the first contact returned. We can also post to /api/Contacts and add a new Contact to the database. Since there are multiple DbSet, you can make the same calls to /api/Addresses.

You can also customize the APIs if you want

app.MapInstantAPIs<MyContext>(config =>
	config.IncludeTable(db => db.Contacts, ApiMethodsToGenerate.All, "addressBook");

This specifies that the all of the CRUD methods should be created for the Contacts table, and it prepends the routes with addressBook.

The source generator approach has an example in the WorkingApi.Generators project (at the moment a NuGet package hasn't been created for this implementation). You specify which DbContext classes you want to map with the InstantAPIsForDbContextAttribute, For each context, an extension method named Map{DbContextName}ToAPIs is created. The end result is similar to the Reflection approach:

[assembly: InstantAPIsForDbContext(typeof(MyContext))]

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddSqlite<MyContext>("Data Source=contacts.db");

var app = builder.Build();



You can also do customization as well

app.MapMyContextToAPIs(options =>
	options.Include(MyContext.Contacts, "addressBook", ApisToGenerate.Get));

Feel free to try both approaches and let Fritz know if you have any issues with either one of them. The intent is to keep feature parity between the two for the forseable future.


Check out Fritz giving a demo, showing the advantage of InstantAPIs on YouTube:

A JSON based API

An API will be generated based on JSON file, for now it needs to be named mock.json.

A typical content in mock.json looks like so:

  "products" : [{
    "id": 1,
    "name": "pizza"
  }, {
    "id": 2,
    "name": "pineapple pizza"
  }, {
    "id": 3,
    "name": "meat pizza"
  "customers" : [{
    "id": 1,
    "name": "customer1"

The above JSON will create the following routes:

HTTP Verb Endpoint
GET /products
GET /products/{id}
POST /products
DELETE /products/{id}
GET /customers
GET /customers/{id}
POST /customers
DELETE /customers/{id}


To use this, do the following:

  1. Create a new minimal API, if you don't already have one:

    dotnet new web -o DemoApi -f net6.0
    cd DemoApi 
  2. Add the NuGet package for Fritz.InstantAPIs:

    dotnet add package Fritz.InstantAPIs --prerelease
  3. In Program.cs, add the following namespace:

    using Mock;
  4. Create a file mock.json and give it for example the following content:

       "products" : [{
         "id": 1,
         "name": "pizza"
  5. Now add the following code for the routes to be created:


Here's an example program:

using Mock;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/", () => "Hello World!");

Coming features

Support for:


This project is covered by a code of conduct that all contributors must abide by. Contributions are welcome and encouraged..

Product Compatible and additional computed target framework versions.
.NET net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed. 
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories (1)

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Repository Stars
Show notes, slides, and samples from the CSharp with CSharpFritz show
Version Downloads Last updated
0.2.0 1,008 3/22/2022
0.2.0-preview-3 157 2/27/2022
0.2.0-preview-2 141 2/24/2022
0.2.0-preview-1 158 2/23/2022
0.1.0 462 2/17/2022

- Introduced a fluent configuration API for defining which tables to include and exclude from the Entity Framework Context.
- Can specify the BaseUrl for a table's APIs
- Added the ability to create APIs from JSON files on disk
- Added ability to specify OpenAPI configuration
- Added Logging for reflection API generation
- Added Codegen APIs
- Added JSON mock APIs