asp.net mvc - Using Viewmodel to populate sql data and add columns -

i take model of table , make viewmodel additions fields, populate view. how do in controller? when model worked i'm not sure how same thing when it's viewmodel. i'm new asp.net mvc appreciated.

model:

        public partial class tbltag         {             public int tagid { get; set; }             public string tagname { get; set; }         } 

viewmodel:

public class tbltagviewmodel {     public string tagname { get; set; }      public string tagnameclr     {                 {             if (tagname == "test")             {                 return "green";             }             else             {                 return "red";             }         }     } } 

controller:

cannot implicitly convert type 'system.data.entity.dbset<_1mvcsqlserver.models.tbltag>' '_1mvcsqlserver.viewmodel.tbltagviewmodel'

now it's viewmodel structure entities different, assume problem. how resolve this?

private testentities db = new testentities();  public actionresult test() {         viewmodel.tbltagviewmodel model = new viewmodel.tbltagviewmodel();         model = db.tbltags;         return(model); } 

here ended work. correct method?

        public actionresult test()     {         list<viewmodel.tbltagviewmodel> list = new list<viewmodel.tbltagviewmodel>();         var model = new viewmodel.tbltagviewmodel();         foreach(tbltag p in db.tbltags)         {             viewmodel.tbltagviewmodel nw = new viewmodel.tbltagviewmodel();             nw.tagname = p.tagname;             list.add(nw);         }          return view(list);     } 

correct method - create business layer, data db layer , pass data view layer (and vice versa, data view layer , pass db layer).

also, recommend @ ioc (di) approach :

business layer:

first @ all, create new classlibrary project , create business layer poco classes , abstraction of repository:

/// <summary> /// business layer class, similar on ef class /// </summary> public class tag {     public int tagid { get; set; }     public string tagname { get; set; } }  public interface irepository {     list<tag> gettaglist(); } 

then create service:

public class service {     private readonly irepository _repository;     public service(irepository repository)     {         if (repository == null)             throw new argumentnullexception("repository");          _repository = repository;     }     public list<tag> gettaglist()     {         return _repository.gettaglist();     } } 

on stage have compiled version of business layer. can add complex logic of application , test it. attent, without db amd view parts!

next step - create db layer

db layer:

create 1 more class library in solution, add link bl project , add code this:

public class efrepository : irepository {     private ... _db;     public efrepository()     {         .....     }     public list<tag> gettaglist()     {         var tags = (from in _db.tbltags select new tag { tagid = i.tagid, tagname = i.tagname }).tolist();     } } 

so, have db , bl layers. , bl layer not depend on db layer, vice versa, db layer depend on bl layer .and it's correct approach, business logic of application should not depended on db!

the last step - view layer.

view layer

you can separate view layer different project too. inside asp.net mvc application. add references db , bl projects

public class tbltagviewmodel {     public string tagname { get; set; }      public string tagnameclr     {                 {             if (tagname == "test")             {                 return "green";             }             else             {                 return "red";             }         }     } } 

and controller:

public class homecontroller : controller {     private readonly service _service;     public homecontroller(irepository repository)     {         if (repository == null)             throw new argumentnullexception("repository");         _service = new service(repository);     }       public actionresult test()     {         list<viewmodel.tbltagviewmodel> list = new list<viewmodel.tbltagviewmodel>();         vat taglist = _service.gettaglist();         foreach (tbltag p in taglist)         {             viewmodel.tbltagviewmodel nw = new viewmodel.tbltagviewmodel();             nw.tagname = p.tagname;             list.add(nw);         }          return view(list);     } } 

and, last step, set db implementation web app:

public class mycontrollerfactory : defaultcontrollerfactory {     protected override icontroller getcontrollerinstance(requestcontext requestcontext, type controllertype)     {         var efrepository = new efrepository();         if (controllertype == typeof(homecontroller))         {             return new homecontroller(efrepository );         }          return base.getcontrollerinstance(requestcontext, controllertype);     } 

pay attention, web-application not depend on db layer, depends on bl layer (this logical too). 1 place set efrepository in web application - in controller factory.

with approach can change efrepository implementation of irepository, different db or fake db. can test part of application without unnecessary relationships. have strong , correct architecture, application depend on business logic layer , not depend on db layer etc. changes in db layer or view layer not affect on logic layer

for mapping similar poco classes (i.e bl , db, bl , view classes) many properties can user automapper