Project maintained by JordanMarr Hosted on GitHub Pages — Theme by mattgraham

SAFE Stack v3 with SSDT Starter

Posted on March 15, 2021

Looking to create an F# powered React app using the new SAFE Stack v3, SQL Server and the new SSDT F# Type Provider? Then you’re in luck! This post will provide a step-by-step tutorial to get you up and running.

In this post we will cover the following:

To get started, you will need the following:

The Stack

For the last two years, I have maintained a greenfield web app that is essentially a SAFE Stack app; it has been a joyful experience! My daily driver has been Visual Studio Professional which I have developed with since .NET v1.1. I chose to write this post around VSCode + Ionide + Azure Data Studio because it is a cross platform stack, and I want to accommodate the many F# devs that are coming over from other backgrounds and other platforms. So this post was a learning experience for me as well!

But I do want to add that VS2019 Community Edition and above has built-in SSDT .sqlproj support via the “SQL Server Data Tools” extension (available as an option in the VS installer).

Installing the SAFE Stack Template

Fable 3 was recently released boasting new features, faster compile times, and a cool new way to launch as a dotnet tool. While Fable 3 does have its own starter template, it only covers the front end. The SAFE Stack takes that and adds:

The new SAFE Stack v3 (currently in beta) supports Fable 3 and is available on NuGet.

Clicking on the link to the latest v3 link should give you the “.NET CLI” install command: As of now, it is:

dotnet new --install SAFE.Template::3.0.1


Assuming you have already installed the .NET 5 CLI, run the command to install the template.

Creating a SAFE Stack App

1) Run the new “SAFE” template.

2) Restore the command line tools that we will use to build and run our SAFE Stack application:

3) Restore NuGet dependencies:

4) OPTIONAL - Initialize a local git repository (the SAFE Stack already includes a .gitignore file!):

Now we can open our new app in Visual Studio Code:

NOTE: If you haven’t already installed the Ionide extension in Visual Studio Code, you should see a prompt in the bottom right corner to install the Recommended Extensions (which is Ionide). Do that.

Assuming Ionide is installed, you should now see an Ionide tab that displays a “SOLUTION EXPLORER” panel on the left with a “src” folder with your three SAFE Stack F# projects:

Running the SAFE Stack App

That’s it! Entering dotnet run from the SafeTodo root folder will run the “Build.fsproj” project which contains FAKE build script tasks that will do the following automatically:

You should be able to view the site in your browser using the port given after the build completes: http://localhost:8080/ NOTE: The current SAFE Stack beta template displays, but I replaced that with http://localhost:8080.

Creating a “SafeTodo” Database with Azure Data Studio

Connecting to a SQL Server Instance

1) In the “Connections” tab, click the “New Connection” button


2) Enter your connection details, leaving the “Database” dropdown set to <Default>.


Creating a new “SafeTodo” Database

USE master
 SELECT name
 FROM sys.databases
 WHERE name = N'SafeTodo'
IF SERVERPROPERTY('ProductVersion') > '12'

NOTE: Alternatively, if you don’t want to manually create the new database, you can install the “New Database” extension in Azure Data Studio which gives you a “New Database” option when right clicking the “Databases” folder.

Create a “Todos” Table

CREATE TABLE [dbo].[Todos]
  [Description] NVARCHAR(500) NOT NULL,

Creating an SSDT Project (.sqlproj)

At this point, you should have a SAFE Stack solution and a minimal “SafeTodo” SQL Server database with a “Todos” table. Next, we will use Azure Data Studio with the “SQL Database Projects” extension to create a new SSDT (SQL Server Data Tools) .sqlproj that will live in our SAFE Stack .sln.

1) Install the “SQL Database Projects” extension.

2) Right click the SafeTodo database and choose “Create Project From Database” (this option is added by the “SQL Database Projects” extension)


3) Configure a path within your SAFE Stack solution folder and a project name and then click “Create”. NOTE: If you choose to create an “ssdt” subfolder as I did, you will need to manually create this subfolder first.


4) You should now be able to view your SQL Project by clicking the “Projects” tab in Azure Data Studio.


5) Finally, right click the SafeTodoDB project and select “Build”. This will create a .dacpac file which we will use in the next step.

Create a TodoRepository Using the new SSDT provider in SQLProvider

Installing SQLProvider from NuGet

Switching back to VSCode, we will install SQLProvider and System.Data.SqlClient to the Server project:

Initialize Type Provider

Next, we will wire up our type provider to generate database types based on the compiled .dacpac file.

1) In the Server project, create a new file, Database.fs. (this should be above Server.fs).

module Database
open FSharp.Data.Sql

let SsdtPath = __SOURCE_DIRECTORY__ + @"/../../ssdt/SafeTodoDB/bin/Debug/SafeTodoDB.dacpac"

// TO RELOAD SCHEMA: 1) uncomment the line below; 2) save; 3) recomment; 4) save again and wait.
//DB.GetDataContext().``Design Time Commands``.ClearDatabaseSchemaCache

type DB = 
        SsdtPath = SsdtPath,
        UseOptionTypes = true

let createContext (connectionString: string) =

2) Create TodoRepository.fs below Database.fs.

module TodoRepository
open FSharp.Data.Sql
open Database
open Shared

/// Get all todos that have not been marked as "done". 
let getTodos (db: DB.dataContext) = 
    query {
        for todo in db.Dbo.Todos do
        where (not todo.IsDone)
            { Shared.Todo.Id = todo.Id
              Shared.Todo.Description = todo.Description }
    |> List.executeQueryAsync

let addTodo (db: DB.dataContext) (todo: Shared.Todo) =
    async {
        let t = db.Dbo.Todos.Create()
        t.Id <- todo.Id
        t.Description <- todo.Description
        t.IsDone <- false

        do! db.SubmitUpdatesAsync()

3) Create TodoController.fs below TodoRepository.fs.

module TodoController
open Database
open Shared

let getTodos (db: DB.dataContext) = 
    TodoRepository.getTodos db

let addTodo (db: DB.dataContext) (todo: Todo) = 
    async {
        if Todo.isValid todo.Description then
            do! TodoRepository.addTodo db todo
            return todo
            return failwith "Invalid todo"

4) Finally, replace the stubbed todosApi implementation in Server.fs with our type provided implementation.

module Server

open Fable.Remoting.Server
open Fable.Remoting.Giraffe
open Saturn
open System
open Shared
open Microsoft.AspNetCore.Http

let todosApi =
    let db = Database.createContext @"Data Source=.\SQLEXPRESS;Initial Catalog=SafeTodo;Integrated Security=SSPI;"
    { getTodos = fun () -> TodoController.getTodos db
      addTodo = TodoController.addTodo db }

let fableRemotingErrorHandler (ex: Exception) (ri: RouteInfo<HttpContext>) = 
    printfn "ERROR: %s" ex.Message
    Propagate ex.Message
let webApp =
    |> Remoting.withRouteBuilder Route.builder
    |> Remoting.fromValue todosApi
    |> Remoting.withErrorHandler fableRemotingErrorHandler
    |> Remoting.buildHttpHandler

let app =
    application {
        url ""
        use_router webApp
        use_static "public"

run app

Run the App!

From the VS Code terminal in the SafeTodo folder, launch the app (server and client):

dotnet run

You should now be able to add todos.


Adding a “Done” Feature

Now that we can add and view todos, we need a way to mark them as complete. First, we need to modifiy the Shared.Todo entity to have an IsDone property.

type Todo =
    { Id : Guid
      Description : string
      IsDone : bool }

module Todo =
    let isValid (description: string) =
        String.IsNullOrWhiteSpace description |> not

    let create (description: string) =
        { Id = Guid.NewGuid()
          Description = description
          IsDone = false }

Now we need to fix the getTodos function so that it loads the new IsDone field. While we’re at it, since we now have an IsDone field, let’s change it so that it returns all todos; that way, we can render the completed todos differently in the UI.

/// Get all todos (regardless of IsDone status) 
let getTodos (db: DB.dataContext) = 
    query {
        for todo in db.Dbo.Todos do
            { Shared.Todo.Id = todo.Id
              Shared.Todo.Description = todo.Description
              Shared.Todo.IsDone = todo.IsDone }
    |> List.executeQueryAsync

Next we will add an updateTodo function to the TodoRepository:

let updateTodo (db: DB.dataContext) (todo: Shared.Todo) = 
    async {
        let! existingTodo =
            query { 
                for t in db.Dbo.Todos do
                where (t.Id = todo.Id)
                select t
            |> Seq.tryHeadAsync

        // Fail if this unexpected scenario occurs
        let existingTodo = existingTodo |> Option.defaultWith (fun () -> failwith "Update failed; Todo was deleted!")

        existingTodo.Description <- todo.Description
        existingTodo.IsDone <- todo.IsDone

        do! db.SubmitUpdatesAsync()
        return todo

Moving our way up the stack, now we need to add a new updateTodo handler on the Shared.ITodosAp:

type ITodosApi =
    { getTodos : unit -> Async<Todo list>
      addTodo : Todo -> Async<Todo>
      updateTodo : Todo -> Async<Todo> }

Then we need to add it to the TodoController::

let updateTodo (db: DB.dataContext) (todo: Todo) = 
    async {
        if Todo.isValid todo.Description 
        then return! TodoRepository.updateTodo db todo
        else return failwith "Invalid todo"

And we need to fix the now broken todosApi implementation in Server.fs:

let todosApi =
    let db = Database.createContext @"Data Source=.\SQLEXPRESS;Initial Catalog=SafeTodo;Integrated Security=SSPI;"
    { getTodos = fun () -> TodoController.getTodos db
      addTodo = TodoController.addTodo db
      updateTodo = TodoController.updateTodo db }

NOTE: We are using a shorthand way of setting the updateTodo field by partially applying the TodoController.getTodos function with the db dependency argument; however, you can also write it out this way if you prefer:

      updateTodo = fun todo -> TodoController.updateTodo db todo

Now for the UI! Let’s make it so that clicking a todo will

For this, we will need

type Msg =
    | GotTodos of Todo list
    | SetInput of string
    | AddTodo
    | AddedTodo of Todo
    | ToggleIsDone of Todo
    | UpdatedTodo of Todo

Then we will implement these handlers in the update function:

    | ToggleIsDone todo ->
        let toggled = { todo with IsDone = not todo.IsDone }        
        model, Cmd.OfAsync.perform todosApi.updateTodo toggled UpdatedTodo
    | UpdatedTodo todo -> 
        { model with 
            Todos = 
                |> (fun t -> 
                    if t.Id = todo.Id then todo else t
        }, Cmd.none

Now for rendering the todos, we want to

                for todo in model.Todos do
                        prop.onClick (fun e -> dispatch (ToggleIsDone todo))
                        prop.text todo.Description 
                            if todo.IsDone then style.textDecoration textDecorationLine.lineThrough
                            style.cursor "pointer"


SAFE Stack v2 allowed you to debug both the client and server via VSCode out-of-the-box. However, SAFE Stack v3 is currently in beta, so the configuration required to do this is not yet ready. We can still debug the server, but to do so, we need to manually launch the server and client separately.

Launch the Server in Debug Mode

Launch the Client Manually

NOTE: You can debug the transpiled JavaScript for the client via the browser’s developer window.


When creating a Release build for deployment, it is important to note that SQLProvider SSDT expects that the .dacpac file will be copied to the deployed Server project bin folder.

Here are the steps to accomplish this:

    <None Include="..\{relative path to SSDT project}\ssdt\SafeTodo\bin\$(Configuration)\SafeTodoDB.dacpac" Link="SafeTodoDB.dacpac">
    { other files... }
      let SsdtPath = __SOURCE_DIRECTORY__ + @"/../../ssdt/SafeTodoDB/bin/Debug/SafeTodoDB.dacpac"
      let SsdtPath = __SOURCE_DIRECTORY__ + @"/../../ssdt/SafeTodoDB/bin/Release/SafeTodoDB.dacpac"

Wrapping Up

If all things went well, you should now have a working SAFE Stack v3 app with a full data layer using the new SQLProvider SSDT type provider!


The companion code for this tutorial is posted on my GitHub account here. Feel free to post any issues you encounter or just to leave a comment. Or hit me up on Twitter!