[ASP.Net Core] Action Filter with Parameter(s)

 ASP.NET Core   Action Filter  

▌Introduction

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Action filters can run code before and after an action method is called.

Sometimes we need to pass parameter(s) to the Action filter.

Here are 2 ways to make it happens:

1.  Inherit Attribute class and create Public prop(s) as the parameter(s) (See how to do it on ASP.NET frameworks)

2.  Use TypeFilter

▋Related articles

1.  [MVC] Pass parameters to ActionFilterAttribute

▌Environment

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▋.NET Core 2.2.104

▌Implement

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▋Inherit Attribute class and create Public prop(s)

▋Action filter

public class LogParamFilter : Attribute, IActionFilter

    {

        public EnumAction Action { get; set; }

        public void OnActionExecuted(ActionExecutedContext context)

        {

            string msg = $"[OnActionExecuted] Request for {this.Action.ToString()}";

            var logger = (ILogger<LogParamFilter>)context.HttpContext.RequestServices.GetService(typeof(ILogger<LogParamFilter>));

            logger.LogInformation(msg);

        }

        public void OnActionExecuting(ActionExecutingContext context)

        {

            string msg = $"[OnActionExecuting] Request for {this.Action.ToString()}";

            var logger = (ILogger<LogParamFilter>)context.HttpContext.RequestServices.GetService(typeof(ILogger<LogParamFilter>));

            logger.LogInformation(msg);

        }

    }

▋Usage

[HttpGet("MyAction1")]

[LogParamFilter(Action = EnumAction.Action1)]

public async Task<IActionResult> MyAction1()

 {

     return Ok();

 }

▋Use TypeFilter

▋Action filter

public class LogFilter: IActionFilter

    {

        private readonly ILogger<LogFilter> _logger = null;

        private readonly EnumAction _action;

        public LogFilter(EnumAction action, ILogger<LogFilter> logger)

        {

            this._logger = logger;

            this._action = action;

        }

        public void OnActionExecuted(ActionExecutedContext context)

        {

            string msg = $"[OnActionExecuted] Request for {this._action.ToString()}";

            this._logger.LogInformation(msg);

        }

        public void OnActionExecuting(ActionExecutingContext context)

        {

            string msg = $"[OnActionExecuting] Request for {this._action.ToString()}";

            this._logger.LogInformation(msg);

        }

    }

Notice that the constructor’s parameters include:

-   Incoming parameter(s), such as EnumAction action. Make sure passing the right number of incoming parameters, or give it a default value.

-   Injected service(s), such as ILogger<LogFilter> logger.

As you can see, TypeFilter is more continent to inject the services from DI container by constructor.

▋Usage

[HttpGet("MyAction2")]

[TypeFilter(typeof(LogFilter), Arguments = new object[] { EnumAction.Action2 })]

 public async Task<IActionResult> MyAction2()

 {

      return Ok();

 }

▋Result

▋Source code

Github

▌Reference

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▋Filters in ASP.NET Core

▋stackoverflow: Is it possible to pass a Service Filter parameters?