AspNetCore.Docs.Samples/fundamentals/minimal-apis/samples/json-apis/Program.cs

using System.Text.Json;
using System.Text.Json.Nodes;
using System.Text.Json.Serialization;
using JSON.Data;
using JSON.Models;
using Microsoft.AspNetCore.Http.Json;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddDbContext<AppDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("ForecastsDatabase")));

// Both the configuration does the same thing
// builder.Services.Configure<JsonOptions>(options =>
// {
//     options.SerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
//     options.SerializerOptions.DictionaryKeyPolicy = JsonNamingPolicy.CamelCase;
//     options.SerializerOptions.WriteIndented = true;
// });

builder.Services.ConfigureHttpJsonOptions(options =>
{
    options.SerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
    options.SerializerOptions.DictionaryKeyPolicy = JsonNamingPolicy.CamelCase;
    options.SerializerOptions.WriteIndented = true;
});

var app = builder.Build();

if (app.Environment.IsDevelopment()) {
    app.UseSwagger();
    app.UseSwaggerUI();
}

/* Writes directly to the Response taking the global JsonOptions for serializing
 * http://localhost:5000/weatherforecast/10/1
 */
app.MapGet("/weatherforecast/{pageIndex:int}/{pageSize:int}", async (int pageIndex, int pageSize , HttpContext context, AppDbContext db) =>
{
    var forecasts = await db.Forecasts.Skip(pageIndex).Take(pageSize).ToListAsync();
    await context.Response.WriteAsJsonAsync<IEnumerable<WeatherForecast>>(forecasts);
});

/*
 * Returns a typed json result taking the global JsonOptions for serializing
 * http://localhost:5000/weatherforecast/2022-01-01
 */

app.MapGet("/weatherforecast/{date:datetime}", async (DateTime date, AppDbContext db) =>
{
    var forecast = await db.Forecasts.SingleOrDefaultAsync(f => f.Date.Equals(date));
    return TypedResults.Json(forecast);
});

/*
 * Writes directly to the Response taking a custom JsonOptions for serializing
 * http://localhost:5000/weatherforecast/2022-01-01/2022-12-31
 */
app.MapGet("/weatherforecast/{from:datetime}/{to:datetime}", async (DateTime from, DateTime to, HttpContext context, AppDbContext db) =>
{
    var forecasts = await db.Forecasts.Where(f => f.Date >= from && f.Date <= to)
        .Select(f => new WeatherForecastModel
        {
            Date = f.Date,
            Summary = f.Summary,
            Temperatures = new Dictionary<string, double>
            {
                {"TemperatureC", f.TemperatureC},
                {"TemperatureF", f.TemperatureC * 9 / 5 + 32}
            }
        }).ToListAsync();
    
    await context.Response.WriteAsJsonAsync<IEnumerable<WeatherForecastModel>>(forecasts, new JsonSerializerOptions
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        DictionaryKeyPolicy = JsonNamingPolicy.KebabCaseLower
    });
});

/* Reads directly from the Request taking the global JsonOptions for deserializing
 * http://localhost:5000/weatherforecast
 * Header: application/json
 * Upload: forecast_1_1_1990_1_1_2023.json
 */
app.MapPost("/weatherforecast", async (HttpContext context, AppDbContext db) =>
{
    if (!context.Request.HasJsonContentType()) return Results.BadRequest();
    var forecasts = await context.Request.ReadFromJsonAsync<IEnumerable<WeatherForecast>>();
    if (forecasts != null) await db.Forecasts.AddRangeAsync(forecasts);
    return await db.SaveChangesAsync() > 0 ? Results.Ok() : Results.BadRequest();
});

/* Reads directly from the Request taking a custom JsonOptions for deserializing
 * TemperatureC should be a number, This will throw an exception if the value of the key is passed as s string e.g. "temperatureC": "45"
 * http://localhost:5000/weatherforecast/11759
 * {
 *	"id": 11759,
 *  "date": "2022-03-12T00:00:00",
 *  "temperatureC": 45,
 *  "summary": "Scorching"
 * }
 */
app.MapPut("/weatherforecast/{id:int}", async (int id, HttpContext context, AppDbContext db) =>
{
    try
    {
        if (!context.Request.HasJsonContentType()) return Results.BadRequest();

        var forecast = await context.Request.ReadFromJsonAsync<WeatherForecast>(new JsonSerializerOptions
        {
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
            NumberHandling = JsonNumberHandling.Strict
        });

        if (forecast == null) throw new ArgumentNullException(nameof(forecast));

        var forecastInDb = await db.Forecasts.FindAsync(id);

        if (forecastInDb == null) throw new ArgumentNullException(nameof(forecastInDb));

        forecastInDb.Date = forecast.Date;
        forecastInDb.TemperatureC = forecast.TemperatureC;
        forecastInDb.Summary = forecast.Summary;

        db.Forecasts.Update(forecastInDb);

        return await db.SaveChangesAsync() > 0 ? Results.Ok() : Results.BadRequest();
    }
    catch (JsonException ex)
    {
        return Results.Problem(ex.Message);
    }
});

/* Formats a request body by adding selected temperature units
 * http://localhost:5000/weatherforecast/formatter?units=kelvin,fahrenheit
 * [
 *	{
 *		"date": "2022-03-12T00:00:00",
 *		"temperatureC": 40,
 *		"summary": "Scorching"
 *	},
 *	{
 *		"date": "2022-03-13T00:00:00",
 *		"temperatureC": -20,
 *		"summary": "Chilling"
 *	}
 * ]
 */
app.MapPost("/weatherforecast/formatter", async (HttpContext context) =>
{
    if (!context.Request.HasJsonContentType()) return Results.BadRequest();
    var forecasts = await context.Request.ReadFromJsonAsync<JsonArray>();

    var units = context.Request.Query["units"];

    var response = new JsonArray();

    if (forecasts == null) return Results.Json(response);
    
    foreach (var jsonNode in forecasts)
    {
        var jsonObject = new JsonObject
        {
            ["date"] = jsonNode?["date"]?.GetValue<DateTime>().ToString("yyyy-MM-dd") ?? null,
            ["summary"] = jsonNode?["summary"]?.GetValue<string>() ?? null
        };

        var temperatureC = jsonNode?["temperatureC"]?.GetValue<double>() ?? default;

        var temperatures = new JsonObject {
            ["celsius"] = double.Round(temperatureC, 2)
        };

        if (units.Contains("kelvin"))
            temperatures["kelvin"] = double.Round(temperatureC + 273.15, 2);

        if (units.Contains("fahrenheit"))
            temperatures["fahrenheit"] = double.Round(temperatureC * 9 / 5 + 32, 2);

        jsonObject.Add("temperatures", temperatures);

        response.Add(jsonObject);
    }

    return Results.Json(response);
});

app.Run();