Program.cs

using Microsoft.EntityFrameworkCore;
using TaskManagerApi.Models;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddCors(options =>
{
    options.AddPolicy("AllowReact", policy =>
    {
        policy.AllowAnyOrigin()
              .AllowAnyMethod()
              .AllowAnyHeader();
    });
});

// Add the Database Context to the "Container"
builder.Services.AddDbContext<TodoContext>(opt =>
    opt.UseSqlite("Data Source=tasks.db"));
// Add services to the container.

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();
app.UseCors("AllowReact");

// Automatically creates database
using (var scope = app.Services.CreateScope())
{
    var db = scope.ServiceProvider.GetRequiredService<TodoContext>();
    db.Database.EnsureCreated();
}

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.UseDefaultFiles();

app.UseStaticFiles();

app.MapFallbackToFile("index.html");

app.MapControllers();

app.Run();