# log request and response
###### tags: `C#`

## 自建 middleware
middleware 掛載在最外層，可記錄到最原始request及最終 response，只是要注意掛載順序

//RecordMiddleware.cs
using System.Text;

namespace test.api.Middlewares;

public class RecordMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger<RecordMiddleware> _logger;
    private readonly string[] _recordStartPath = { "/api/wallet", "/wallet"};

    public RecordMiddleware(RequestDelegate next, ILogger<RecordMiddleware> logger)
    {
        _next = next;
        _logger = logger;
    }

    public async Task Invoke(HttpContext httpContext)
    {
        var guid = Guid.NewGuid();
        var path = httpContext.Request.Path.ToString().ToLower();

        if (!IsRecordPath(path))
        {
            await _next(httpContext);
            return;
        }

        var requestBody = await GetRequest(httpContext.Request);
        _logger.LogInformation($"guid:{guid}, path:{path}, request:{requestBody}");
        
        var originBody = httpContext.Response.Body;
        var memStream = new MemoryStream();
        httpContext.Response.Body = memStream;
        
        await _next(httpContext);
        
         memStream.Position = 0;
         var originalResponseBody = new StreamReader(memStream).ReadToEnd();
         _logger.LogInformation($"guid:{guid}, response:{originalResponseBody}");
         memStream.Position = 0;
         //不管是否有修改都需塞回原本的 Response.Body
         await memStream.CopyToAsync(originBody).ConfigureAwait(false);
    }
    
    private static async Task<string> GetRequest(HttpRequest request)
    {
        if (request.HasFormContentType)
        {
            var form = await request.ReadFormAsync();
            var enumerable = form.Select(x=>$"{x.Key}:{x.Value}");
            return string.Join(',', enumerable);
            //return JsonConvert.SerializeObject(form);
        }
        else
        {
            var body = await GetBody(request);
            return body;
        }
    }
    
    private static async Task<string> GetBody(HttpRequest request)
    {
        request.EnableBuffering();
        using var sr = new StreamReader(request.Body, Encoding.UTF8);
        var body = await sr.ReadToEndAsync();
        
        //stream 讀取後會變成 disposed。目前不知道其他作法，因此只能重新 assign request, if not will get Cannot access a disposed object
        var requestContent = new StringContent(body, Encoding.UTF8, "application/json");
        request.Body = await requestContent.ReadAsStreamAsync();
        request.ContentType = "application/json";
        request.Body.Position = 0;
        
        return body;
    }

    private bool IsRecordPath(string path)
    {
        return true;
        return _recordStartPath.Any(s => path.StartsWith(s));
    }
}

//startup.cs 註冊
app.UseMiddleware<RecordMiddleware>();

#### 相關連結
[Asp.net core Middleware change request response](https://hackmd.io/UEm0qOIwSdmemX4CepkBxQ)

## 自建 action filter
可是自已需求掛載到需要的 controller 上，但 filter 本身運作機制的問題，會無法記錄到 middleware 及 exception filter 的運作結果

//RecordActionFilter
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Newtonsoft.Json;

namespace test.api.Middlewares;

public class RecordActionFilter : IActionFilter
{
    private readonly ILogger<RecordActionFilter> _logger;

    public RecordActionFilter(ILogger<RecordActionFilter> logger)
    {
        _logger = logger;
    }

    public void OnActionExecuting(ActionExecutingContext context)
    {
        var readActionExcutedRequestBody = ReadActionExcutedRequestBody(context);
        _logger.LogInformation("test "+readActionExcutedRequestBody);
    }

    public void OnActionExecuted(ActionExecutedContext context)
    {
        var actionExcutedResponseBody = GetActionExcutedResponseBody(context);
        _logger.LogInformation("test "+actionExcutedResponseBody);
    }
    
    private string ReadActionExcutedRequestBody(ActionExecutingContext context)
    {
        string requestBody = "";
        if (context != null)
        {
            var request = context.HttpContext.Request;
            request.Body.Position = 0;
            StreamReader stream = new StreamReader(request.Body);
            requestBody = stream.ReadToEnd();
            request.Body.Position = 0;
        }
        return requestBody;
    }
 
    private string GetActionExcutedResponseBody(ActionExecutedContext context)
    {
        string responseBody = "";
        if (context.Result != null)
        {
            if (context.Result is ObjectResult)
                responseBody = JsonConvert.SerializeObject(((ObjectResult)context.Result).Value);
            if (context.Result is JsonResult)
                responseBody = JsonConvert.SerializeObject(((JsonResult)context.Result).Value);
        }
        return responseBody;
    }
}


//startup.cs 中註冊
services.AddScoped<RecordActionFilter>();

//掛載到 controller 上
[ServiceFilter(typeof(RecordActionFilter))]

#### 相關連結
[asp.net core ActionExecutedContext 获取Request.Body内容](https://www.cnblogs.com/sunliyuan/p/14250938.html)
[ASP.NET Core 2 系列 - Filters](https://blog.johnwu.cc/article/ironman-day14-asp-net-core-filters.html)

## .net core 'UseHttpLogging' middleware
in .net core 有內建的 middleware, 但需用原生的 log, 用 Serilog 好像不 work

//in startup.cs 
builder.Services.AddHttpLogging(logging => {
    logging.LoggingFields = Microsoft.AspNetCore.HttpLogging.HttpLoggingFields.ResponseBody;
}); //設定記 response body

app.UseHttpLogging(); //啟用


// in appsettings.Development.json LogLevel add
{
    "Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware": "Information"
}

#### 相關連結
[HTTP Logging in ASP.NET Core](https://learn.microsoft.com/en-us/aspnet/core/fundamentals/http-logging/?view=aspnetcore-6.0#enabling-http-logging)
[HTTP Logs With 'UseHttpLogging' Middleware .NET6 Feature](https://www.learmoreseekmore.com/2021/12/dotnet6-http-logs-with-usehttplogging-middleware.html)

## .net core 'UseSerilogRequestLogging' middleware
使用 Serilog 可用這個，但只記錄時間即回傳狀態

app.UseSerilogRequestLogging();

#### 相關連結
[Reducing log verbosity with Serilog RequestLogging](https://andrewlock.net/using-serilog-aspnetcore-in-asp-net-core-3-reducing-log-verbosity/)