ASP.NET Core模型绑定程序结果记录

Question

I would like to increase / improve my logging.

So far I had in each controller action code like

  public asyc Task<IActionResult> Action1(int id, [FromBody] RequestModel request) {
    string log = $"{nameof(Action1)}(id: {id}, request: {request?.ToJson()})";
    _logger.LogInformation(log);

The main purpose was to see whats actually reaching the controller action.

I removed it since it cluttered the code heavily (eg for methods with a lot of paramters). But now I am unhappy with the result that the logs do not show the information any more (and I needed them to investigate some unexplainable bugs).

Is there a way to hook up into the model binder result (eg via a service filter) to log the model binder result?

---

Works like charm: thanks to Shahzad Hassan

  public class MethodCallParameterLogger : IAsyncActionFilter
  {

    public ILoggerFactory LoggerFactory { get; set; }

    public MethodCallParameterLogger(ILoggerFactory loggerFactory)
    {
      LoggerFactory = loggerFactory;
    }

    public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
    {

      LoggerFactory

        // the display name contains the controller name space, controller name, method name and the postfix " (ActionLogger)"
        .CreateLogger(context.ActionDescriptor.DisplayName.Split(" ")[0])

        // MIND THAT THIS LOGS EVEN SENSITIVE DATA (e.g. credentials) !!!
        .LogInformation(JsonConvert.SerializeObject(context.ActionArguments));

      var resultContext = await next();

    }

  }

Answer 1

I think you can use an ActionFilter instead. ActionFilters are executed after the model binding, so you can retrieve the parameters from the ActionExecutingContext . You can override the OnActionExecuting method and log whatever is required:

public class LogParamsFilter : ActionFilterAttribute
{
    private readonly ILogger<LogsParamsFilter> _logger;

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

    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var id = (int)context.ActionArguments["id"];
        var request = context.ActionArguments["request"] as RequestModel;
        var action = context.ActionDescriptor.DisplayName;

        string log = $"{action)}(id: {id}, request: {request?.ToJson()})";
        _logger.LogInformation(log);

        base.OnActionExecuting(context);
    }
}

You would need to use it as TypeFilter on the controller action so that its dependencies ie ILogger is resolved via DI.

[TypeFilter(typeof(LogParamsFilter))]
public asyc Task<IActionResult> Action1(int id, [FromBody] RequestModel request)
{
    ...
}

Or you can register it globally in the startup for all controllers:

services.AddMvc(options => options
    .Filters.Add(new TypeFilterAttribute(typeof(LogParamsFilter))));

In order to use it as a generic filter for all controller actions, iterate through the context.ActionArguments.Keys property and log the value for each key. You would need to do some type checkings and call .ToJson() if the type of the ActionArgument is RequestModel.

I hope that helps.