c# - Return type IResult<T> -

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i try solve problem in wpf app mvvm design. need return on database access more "data":

  • result messages
  • return value
  • and if database successful

so create interface return type, here it:

public interface iresult<t>  {     bool issuccess { get; set; }     string resultmessage { get; set; }     t returnvalue { get; set; }  }

this interface implements class:

public class dbresult: iresult<ilist<archive>> {     public bool issuccess{ get; set;}     public string resultmessage{ get; set;}     public ilist<archive> returnvalue { get; set; }  }

method in class on databases access have return type iresult<archive>, archive class generated linq sql.:

public interface iarchivedbmanager {     iresult<archive> loadconversationto(string nick, datetime todt); }  [export(typeof(iarchivedbmanager))] public partial class archivedbmanager : iarchivedbmanager {     public iresult<archive> loadconversationto(string nick, datetime todt)     {         var result = new dbresult();          try         {             var query = m in _dc.archive                         m.nick == nick                         m.time <= todt                         orderby m.time                         select m;              result.returnvalue = query.tolist();              if (query.count() == 0)             {                 result.resultmessage = "for specified search criteria found no record in database.";                 result.issuccess = false;             }             else             {                 result.resultmessage =                     string.format("for specified search criteria found {0} record in database.", query.count());                 result.issuccess = true;             }              return result;         }         catch (exception exception)         {              throw exception;         }     }  }

class archivedbmanager inject mef in view model class.

i have question:

  1. what correct solution problem in mvvm? scenario view model create through archivedbmanager access database, example if database table empty, archivedbmanager class return message "archive empty" , view model show message in view user.

  2. it right create report of search results in database in "archivedbmanager class (it class on database access)"

  3. what think solution?

keep simple: don't need interface or class.

you need ask result, , method should throw exception error message goes wrong.

this kind of success result messages: result.resultmessage = "for specified search criteria found no record in database."; not belong business logic or data layer. ui layer should responsible showing messages user.


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