Dynamic property or Extended property in C#

I was busy to create architecture of asp.net (C#) project. In the time of development, I faced a situation where it will be good to have a dynamic property generation. I did some search, and found many examples. But after going through all, I found something, which is really nice and solve my problem. My problems are-

1>  I need to get all the data fetched from table in DB in a custom and pre-defined model in c#, but sometime DB queries can return some columns which are not in the defined properties of predefined model.

2>  When I do serialization of the model in c#, it should serialize in normal and proper way, with or without extra columns returned from DB.

Example-

Suppose, I define a model –

Public class EmpModel{

Public string EmpName{get; set;}

Public string EmpId{get; set;}

}

And I also write three SQL queries-

SELECT EmpName,EmpId,EmpAddress from tbl_Employee

SELECT EmpName,EmpId,EmpDept from tbl_Employee

SELECT EmpName,EmpId,EmpDOB from tbl_Employee

Now, as you can see, the queries are returning three columns, but the model only has two properties. I cannot manage EmpAddress, EmpDept and EmpDOB in model. As well as, the 3^rd field will be different in type also. To manage this situation, I found-

1>     AssemblyBuilder

2>     ModuleBuilder

3>     TypeBuilder

4>     FieldBuilder

5>     PropertyBuilder

6>     MethodAttributes

7>     MethodBuilder

These are the main building blocks of my solution.

The theory of the solution is, I have to create a class which will have EmpModel as a base class and with the properties (Extra properties) needed. All these, need to be done dynamically.

For all these, I managed to write two method sets(Three methods), which will handle everything for me-

MethodSet 1 (to bind DB columns with Model properties)-[Contains two methods]

public void getModelFromObject<T, T1>(object valu, ref List<T> el,Dictionary<string,Type> props) where T1 : T, new()

        {

            DataTable dt = ((DataSet)valu).Tables[0];

            Type dynamicType = getType(typeof(T).Name+ "Ext", props, typeof(T1));

            foreach (DataRow dr in ((DataSet)valu).Tables[0].Rows)

            {

                T item = (T)Activator.CreateInstance(dynamicType);

                getObject<T>(dr, ref item, dt);

                T tsts = item;

                ((List<T>)el).Add(item);

            }

        }

public void getObject<T>(DataRow dr,ref T obj, DataTable dt)

        {

          

            foreach (DataColumn dc in dt.Columns)

            {

                if (obj.GetType().GetProperty(dc.ColumnName) != null)

                {

                   

                        obj.GetType().GetProperty(dc.ColumnName).SetValue(obj, dr[dc.ColumnName], null);

                 

                }

            }

        }

MethodSet 2(to create extended properties)-[Contains one method]

  public Type getType(string dynamicClassName, Dictionary<string, Type> propertyList, Type baseClassType)

        {

            bool isNewProperties = false;

            AssemblyBuilder assemblyBilder = System.Threading.Thread.GetDomain().DefineDynamicAssembly

            (new AssemblyName(dynamicClassName + "Assembly"), AssemblyBuilderAccess.Run);

            ModuleBuilder moduleBilder = assemblyBilder.DefineDynamicModule(dynamicClassName + "Module");

            TypeBuilder typeBilder = moduleBilder.DefineType(dynamicClassName, TypeAttributes.Public | TypeAttributes.Class, baseClassType);

            string propertyName = null;

            Type propertyType = null;

            var baseClassObj = Activator.CreateInstance(baseClassType);

            foreach (var prop in propertyList)

            {

                propertyName = prop.Key;

                propertyType = prop.Value;

                var propExist = baseClassObj.GetType().GetProperty(propertyName);

                if (propExist != null)

                {

                    continue;

                }

                FieldBuilder filedBilder = typeBilder.DefineField("_" + propertyName, propertyType, FieldAttributes.Private);

                PropertyBuilder propertyBilder = typeBilder.DefineProperty(propertyName, System.Reflection.PropertyAttributes.None, propertyType,

                            new Type[] { propertyType });

               

                MethodAttributes GetSetAttr = MethodAttributes.Public | MethodAttributes.HideBySig;

                MethodBuilder currGetPropMthdBilder = typeBilder.DefineMethod("geter", GetSetAttr, propertyType, null);

                ILGenerator currtGetIL = currGetPropMthdBilder.GetILGenerator();

                currtGetIL.Emit(OpCodes.Ldarg_0);

                currtGetIL.Emit(OpCodes.Ldfld, filedBilder);

                currtGetIL.Emit(OpCodes.Ret);

                MethodBuilder currSetPropMthdBilder = typeBilder.DefineMethod("seter", GetSetAttr, null, new Type[] { propertyType });

                ILGenerator currSetIL = currSetPropMthdBilder.GetILGenerator();

                currSetIL.Emit(OpCodes.Ldarg_0);

                currSetIL.Emit(OpCodes.Ldarg_1);

                currSetIL.Emit(OpCodes.Stfld, filedBilder);

                currSetIL.Emit(OpCodes.Ret);

                propertyBilder.SetGetMethod(currGetPropMthdBilder);

                propertyBilder.SetSetMethod(currSetPropMthdBilder);

                isNewProperties = true;

            }

            if (isNewProperties == false)

            {

                return baseClassType;

            }

            return typeBilder.CreateType();

        }

And now, the use of these methods-

     List<IEmp> obj = new List<IEmp>();

            Dictionary<string, Type> props= new Dictionary<string, Type>();

            props.Add("EmpAddress", typeof(string));//if more then one add more.

            modelPlatform.init().getModelFromObject<IEmp,Emp>(ds, ref obj, val);//ds- is the dataset returned from DB

           

            return obj;

Same for two other queries also.

That’s it, Enjoy.

Advance LED display

I did some betterment in Led display. By using 8051/52, this display is working smoothly. All the code and the character generation is done by C. I used only 15 pins of Micro-controller for this display. Another important component used here is 74HC595. To use minimum amount of PINs, I used parallel to serial conversion. 74HC595 is basically used as a parallel to serial converter. 

Demo is here- youtu.be/WFTibkb-cx4

To get the code provide your mail id in comment section-

MVPC (semi- MVVM) implementation for Android app Development

Introduction

When I was trying to implement MVC for Android Application, the concept of “Observer” really attracts me. It really put me in a situation, where, I have to think, should I go for MVC or MVPC.  Because, I think, MVPC would be more organized and maintainable way for this Android application.  Along with this thinking, possibility of total segregation of event listeners in code, make me think about MVPC for this project seriously.

[Note: Observer is the interface to be implemented by objects that receive notification of updates on an Observable object. (Observer Triggers, when Observable notifies any changes on it)]

Why MVPC?

Model-View-Presenter-Controller. In MVC, View notifies Controller, Controller notifies Model, and Model notifies View. It is really very compact and smart enough Architecture. But, Presenter is another useful architecture entity. It will give another level of abstraction to the project between View and Controller. This will make the view much independent and make controller more flexible.  With this architecture, we can replace the existing view with a new one, so smartly, that we may have to do no changes in Controller.

Do we really need MVPC in Android Application?
We may not need MVPC for today or tomorrow, but day after tomorrow. As year goes, a View of an application becomes monotonous to the user, or else, we may need to implement different views (Theme) to the project. To do all the above, we really don’t want to hamper any application flow.  MVPC will be one of the best fit architecture for this.

Code Example-
In MainActivity.java-

public class MainActivity extends Activity  {

       public User mUser;

       UserController controller;

       UserPresenter presenter;

      

       @Override

       protected void onCreate(Bundle savedInstanceState) {

              super.onCreate(savedInstanceState);

              setContentView(R.layout.activity_main);

              mUser= new User();

              controller= new UserController(this);

              mUser.addObserver(controller);

              presenter= new UserPresenter(mUser);

             

              Button test_btn=(Button) findViewById(R.id.btn_Test);

              Button test_btn2=(Button) findViewById(R.id.btn_Test2);

              test_btn.setOnClickListener(presenter);

              test_btn2.setOnClickListener(presenter);

       }

In UserPresenter.java-

public class UserPresenter implements OnClickListener {

       private User _model;

       public UserPresenter(User model)

       {

              _model=model;

       }

      

       @Override

       public void onClick(View v) {

              switch(v.getId())

              {

              case R.id.btn_Test:

                     _model.setCount();

                     break;

              case R.id.btn_Test2:

                     _model.setCount();

                     _model.setCount();

                     break;

             

              }

       }

}

In UserModel.java-

public class User extends Observable {

       public int count=0;

       public User(){

             

       }

       public void setCount()

       {

              count++;

              setChanged();

              notifyObservers();

       }

}                     

In UserController.java-

public class UserController implements Observer {

    public User mUser;

    private Activity _act;

    public UserController(Activity act )

    {

       _act=act;

    }

   

       @Override

       public void update(Observable observable, Object data) {

              TextView lbl= (TextView)_act.findViewById(R.id.lbl_Text);

              lbl.setText(""+((MainActivity)_act).mUser.getCount());

       }

}