Solved

How to instantiate my business object without useing 'new' keyword.

Posted on 2010-11-10
10
629 Views
Last Modified: 2012-05-10
Below is my Fetch procedure, and this is in BusinessObjectFactory class -  this procedure takes two parameters - 1st parameter I want to send the type of class and other parameter is datarow/data table/ data set.

AssetToleranceBO is my class.

I want to instantiate my class 'AssetToleranceBO ' as below.
AssetToleranceBO assetTol = BusinessObjectFactory.Fetch(typeof(AssetToleranceBO), dr);

Now my question is how to define the parameters in Fetch method?
And also, entitiType.InvokeMember is expecting object[] args - how do I pass this, I want to pass either datarow / data table / data set
Can anyone help me?

public static object Fetch(object objBusiness, object criteria) 

        {

            Type entitiType = objBusiness.GetType();

            object obj = Activator.CreateInstance(entitiType);

            entitiType.InvokeMember("FetchData", BindingFlags.InvokeMethod, null, obj, criteria);

            return obj;

        }





        public class AssetToleranceBO : EntityBusinessBase

    {

        string _acctID;

        string _name;

        

               

        public string ID

        {

            get { return _acctID; }

            set { _acctID = value; }

        }

        

        public string CLASS

        {

            get { return _name; }

            set { _name = value; }

        }





        /// <summary>

        /// Fetches the data.

        /// </summary>

        /// <param name="criteria"></param>

        protected override void FetchData(DataRow criteria)

        { 

            _acctID = criteria["gpq_acct_id"].ToString();

            _name = criteria["acct_name"].ToString();

        }

}

Open in new window

0
Comment
Question by:GouthamAnand
  • 4
  • 3
  • 2
  • +1
10 Comments
 
LVL 52

Expert Comment

by:Carl Tawn
ID: 34105803
For starters the parameter type would be Type, as in:

     public static object Fetch(Type objBusiness, object criteria)
     {

     }

For the object[] parameter you would do:

     new object[] { yourParameterValue }
0
 
LVL 19

Expert Comment

by:Daniel Van Der Werken
ID: 34106219
This worked for me but I had to use the "new" keyword in the method call.  Otherwise, the type was System.RunTimeType in the Fetch() method and I wasn't able to figure out why.  
 

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Reflection;

using System.ServiceProcess;

using System.Text;

using System.Windows.Forms;



namespace WindowsFormsApplication1

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

            BusinessObjectFactory.AssetToleranceBO assetTol = (BusinessObjectFactory.AssetToleranceBO)BusinessObjectFactory.Fetch( new BusinessObjectFactory.AssetToleranceBO(), "Hello There" );

        }

    }



    public static class BusinessObjectFactory

    {

        static BusinessObjectFactory() { }



        public static object Fetch( object objBusiness, object criteria )

        {

            Type entityType = objBusiness.GetType();

            if ( !string.Equals( entityType.UnderlyingSystemType.Name, "RunTimeType", StringComparison.InvariantCultureIgnoreCase ) )

            {

                object obj = Activator.CreateInstance( entityType );

                entityType.InvokeMember( "FetchData", BindingFlags.InvokeMethod, null, obj, new object[] { criteria } );

                return obj;

            }

            else

            {

                return null;

            }

        }



        public class AssetToleranceBO

        {

            public AssetToleranceBO() { }



            public void FetchData( string someString )

            {

                MessageBox.Show( someString );

            }

        }

    }

}

Open in new window

0
 

Author Comment

by:GouthamAnand
ID: 34106989
It says - No parameterless constructor defined for this object. - at object obj = Activator.CreateInstance( entityType );

I have defined parameterless constructor , but still it says - "No parameterless constructor defined for this object"
0
 
LVL 19

Expert Comment

by:Daniel Van Der Werken
ID: 34107707
That's what happened to me when I initially tried it with

BusinessObjectFactory.AssetToleranceBO assetTol = (BusinessObjectFactory.AssetToleranceBO)BusinessObjectFactory.Fetch( typeof( BusinessObjectFactory.AssetToleranceBO ), "Hello There" );


instead of BusinessObjectFactory.AssetToleranceBO assetTol = (BusinessObjectFactory.AssetToleranceBO)BusinessObjectFactory.Fetch( new BusinessObjectFactory.AssetToleranceBO(), "Hello There" );

which are you trying.  Are you trying to use a Type parameter or an object parameter?  I could not get it to work with the Type parameter.  Basically, the type it resolves out to is System.RunTimeType which apparently has no default parameterless constructor.  
0
 
LVL 7

Accepted Solution

by:
keustermans earned 500 total points
ID: 34119470
Try the Code below. You can create any kind of object with it.

 public class ObjectFactory
    {

        public static T CreateInstance<T>()
        {
            object instance = Activator.CreateInstance(typeof(T));
            return (T)instance;
        }


        public static T CreateInstance<T>(string invokeMember, object[] param)
        {
            Type type;
            type = typeof(T);
            object instance = Activator.CreateInstance(type);
            type.InvokeMember(invokeMember, BindingFlags.InvokeMethod, null, instance, param);
            return (T)instance;
        }
    }
0
What Is Threat Intelligence?

Threat intelligence is often discussed, but rarely understood. Starting with a precise definition, along with clear business goals, is essential.

 
LVL 7

Assisted Solution

by:keustermans
keustermans earned 500 total points
ID: 34119572
You can use the class as follows:

 public class TestClass
    {
        public string a { get; set; }
        public string b { get; set; }

        public string ab
        {
            get
            {
                return a + b;
            }
        }

        public void DoStuff(string arg1, string arg2)
        {
            a = arg1;
            b = arg2;
        }


    }

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            TestClass test = ObjectFactory.ObjectFactory.CreateInstance<TestClass>();
            test.a = "abc";
            test.b = "efg";

        }

        private void button2_Click(object sender, EventArgs e)
        {
            TestClass test = ObjectFactory.ObjectFactory.CreateInstance<TestClass>("DoStuff",new object[]{"Test","Class"});
        }
    }
0
 

Author Comment

by:GouthamAnand
ID: 34123103
This is what I am lookin for. Thanks alot.
But I am getting an error at entityType.InvokeMember. It says - "Method Business.Entities.AssetToleranceBO.FetchData' not found.

I have 'FetchData' method in AssetToleranceBO. I am not sure why it is not able to reach there.

please help me. Below is my code.
DataRow dr = AssetToleranceDA.FetchTolerance(assetID);



            AssetToleranceBO assetTol = BusinessObjectFactory.CreateBusinessObject<AssetToleranceBO>(typeof(AssetToleranceBO), dr); 





public static TObject CreateBusinessObject<TObject>(Type objBusiness, object criteria) 

        {

            Type entityType;



            entityType = typeof(TObject);



            object objInstance = Activator.CreateInstance(entityType, true);



            object[] param = new object[] { criteria };



            entityType.InvokeMember("FetchData", BindingFlags.InvokeMethod, null, objInstance, param);



            return (TObject)objInstance;

            

        }

Open in new window

0
 

Author Closing Comment

by:GouthamAnand
ID: 34124264
Thanks a lot. This is exactly what I am looking for.
0
 
LVL 7

Expert Comment

by:keustermans
ID: 34126960
Hi,

It could be because your method si expecting a datarow and you are passing it an object.

Teh solution might be that you actualy put a datarow in the param object array.

I haven't tested this but it seems to be the obvious answer to me.
0
 
LVL 7

Expert Comment

by:keustermans
ID: 34126961
Oh by the way you might have to cast it back to Datarow in the the FetchData function.
0

Featured Post

How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

Join & Write a Comment

We all know that functional code is the leg that any good program stands on when it comes right down to it, however, if your program lacks a good user interface your product may not have the appeal needed to keep your customers happy. This issue can…
This article is for Object-Oriented Programming (OOP) beginners. An Interface contains declarations of events, indexers, methods and/or properties. Any class which implements the Interface should provide the concrete implementation for each Inter…
In this seventh video of the Xpdf series, we discuss and demonstrate the PDFfonts utility, which lists all the fonts used in a PDF file. It does this via a command line interface, making it suitable for use in programs, scripts, batch files — any pl…
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…

759 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

22 Experts available now in Live!

Get 1:1 Help Now