MVC4 filter use and how to control all action and part action

The filters in MVC are divided into four types: Iactionfilter (action Filter), Iauthorizationfilter (authorization filter), Iexceptionfilter (Exception filter), Iresultfilter (Result filter) literal translation, do understand it.

Here is the iactionfilter example, there are two methods in this interface, namely: onactionexecuting (Action execution before execution) and onactionexecuted (Action execution after execution),

Now we want to have all the actions in a controller execute this filter and we need to rewrite the method inside.

   Public classLogincontroller:controller {//        //GET:/login/         PublicActionResult Index () {returnView (); }           PublicActionResult Login () {stringName = httpcontext.request["UserName"]; viewdata["name"] =name; returnView (); }        protected Override voidonactionexecuting (ActionExecutingContext filtercontext) {//object[] attrs = FilterContext.ActionDescriptor.GetCustomAttributes (typeof (NoFilter), true); //if (attrs. Length = = 1)//has NoFilter property//{            //return; //}            stringName = filtercontext.httpcontext.request["UserName"]; if(string. IsNullOrEmpty (name)) {FilterContext.HttpContext.Response.Write ("<script>alert (' name cannot be empty! ');</script>");            FilterContext.HttpContext.Response.End (); }        }    }

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This will execute the filter before each action executes.

Here's how to make the action of index not execute, just execute on login. There are 2 ways to achieve this:

The first: The code is modified as follows:

  Public classLogincontroller:controller {//        //GET:/login/[NoFilter] PublicActionResult Index () {returnView (); }                 PublicActionResult Login () {stringName = httpcontext.request["UserName"]; viewdata["name"] =name; returnView (); }        protected Override voidonactionexecuting (ActionExecutingContext filtercontext) {//filter out the action labeled NoFilter            Object[] Attrs = FilterContext.ActionDescriptor.GetCustomAttributes (typeof(NoFilter),true); if(Attrs. Length = =1)//has NoFilter property            {                return; }            stringName = filtercontext.httpcontext.request["UserName"]; if(string. IsNullOrEmpty (name)) {FilterContext.HttpContext.Response.Write ("<script>alert (' name cannot be empty! ');</script>");            FilterContext.HttpContext.Response.End (); }        }    }     Public classNofilter:filterattribute, Iactionfilter { Public  voidonactionexecuting (ActionExecutingContext filtercontext) {//        }         Public  voidonactionexecuted (ActionExecutedContext filtercontext) {//        }    }

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The second type: The code is modified as follows:

  Public classLogincontroller:controller {//        //GET:/login/         PublicActionResult Index () {returnView (); } [Loginfilter] PublicActionResult Login () {stringName = httpcontext.request["UserName"]; viewdata["name"] =name; returnView (); }        //protected override void OnActionExecuting (ActionExecutingContext filtercontext)//{        //    //filter out the action labeled NoFilter//object[] attrs = FilterContext.ActionDescriptor.GetCustomAttributes (typeof (NoFilter), true); //if (attrs. Length = = 1)//has NoFilter property//    {        //return; //    }        //String name = filtercontext.httpcontext.request["UserName"]; //if (string. IsNullOrEmpty (name))//    {        //FilterContext.HttpContext.Response.Write ("<script>alert (' name cannot be empty!        ');</script> "); //filterContext.HttpContext.Response.End (); //    }        //}    }     Public classLoginfilter:filterattribute, Iactionfilter { Public voidonactionexecuting (ActionExecutingContext filtercontext) {stringName = filtercontext.httpcontext.request["UserName"]; if(string. IsNullOrEmpty (name)) {FilterContext.HttpContext.Response.Write ("<script>alert (' name cannot be empty! ');</script>");            FilterContext.HttpContext.Response.End (); }        }         Public voidonactionexecuted (ActionExecutedContext filtercontext) {//        }    }

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Add: 1. Custom filter filters must inherit FilterAttribute.

2. Define a filter to define the order in which the filters are executed. For example: Mark on action:

[NoFilter (order=2)]

[Loginfilter (Order=1)]

This executes the loginfilter before executing the nofilter when the action is executed.