c# - Base controller for exporting data to excel instead of returning viewmodel -

i have web api project controllers return view model client application can show data grids.

this sample controller sample method can explain better:

public class samplecontroller: apicontrollerbase {       [httpget, appauthorize(null)]      public httpresponsemessage getsampledata(int employeeid, datetime fromdate, datetime todate)      {          httpresponsemessage returnval = null;           // new, instead of returning model return file          // don't want add every controller, have in base controller or something?          // check if user request export grid excel           if (this.request.getquerystrings().containskey("exportdata"))          {              // here have generate excel file               returnval = new httpresponsemessage(httpstatuscode.ok);               returnval.content = new bytearraycontent(filebytes);               returnval.content.headers.contentdisposition = new headers.contentdispositionheadervalue("attachment");              returnval.content.headers.contentdisposition.filename = filename;              returnval.content.headers.contenttype = new mediatypeheadervalue("application/octet-stream");               return returnval;          }           var model = samplerepository.getconsumptionsummary(employeeid, fromdate.touniversaltime().date, todate.touniversaltime().date);           if (model != null)          {              returnval = request.createresponse(httpstatuscode.ok, new model.custom.jsonresponse {                  data = model,                  message = "",                  num = model.count,                  success = true              });          } else {              returnval = request.createresponse(httpstatuscode.ok, new model.custom.jsonresponse {                  data = null,                  message = "there error processing data.",                  num = 0,                  success = false,                  code = "err-001"              });          }           return returnval;      }  } 

on client, user can request export same grid data excel. in scenario use same method grid generate excel file , return browser.

if (this.request.getquerystrings().containskey("exportdata")) { } 

this line magic in method know if user has requested export data excel.

but, don't want put logic on each method on each controller, have in separate place applies methods.

i thinking in creating filter can place in methods or controllers want happen logic.

the code should using in filter or alternative approach be:

// check if user request export grid excel if (this.request.getquerystrings().containskey("exportdata")) {     // here have generate excel file...      returnval = new httpresponsemessage(httpstatuscode.ok);     returnval.content = new bytearraycontent(filebytes);     returnval.content.headers.contentdisposition = new headers.contentdispositionheadervalue("attachment");     returnval.content.headers.contentdisposition.filename = filename;     returnval.content.headers.contenttype = new mediatypeheadervalue("application/octet-stream");     return returnval; } 

any clue?

you have filestreamresult should you, don't have declare things.

i create custom actionresult. in 1 of our applications use custom "excelresult" :

public class excelresult : filestreamresult {     public excelresult(stream filestream, string filename)         : base(filestream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")     {         filedownloadname = filename;     } } 

so when need generate , return excel file, (we extracted bit method in our "basecontroller") :

using (memorystream result = (memorystream)exportservice.exporttoexcel(foo)) {     return excel(new memorystream(result.getbuffer()), filename); } 

and excel method (in our base controller) :

public excelresult excel(stream stream, string filename) {     if (stream == null)         throw new argumentnullexception("stream");     if (string.isnullorwhitespace(filename))         throw new argumentnullexception("filename");      return new excelresult(stream, filename); }