CODEWITHSUNDEEP
c#asp.net.net
Adeptus
Adeptus

Reputation: 147

Converting from one class to another

I am calling a webservice that returns an array of one of four custom classes. All classes have the same inner contents - one string named Description, and another string named Value. I am trying to write a single method that can accept any of the four classes, and put its contents into a dropdown list's datasource.

Is there a way to convert from an unknown composite class to a specified class with the same contents? Or strip the contents out?

Or will I have to write four identical functions with different datatypes?

edit: added code

    myDropDown.DataSource = CreateDataSource(myWebServiceResponse.Items);
    myDropDown.DataTextField = "DescriptionField";
    myDropDown.DataValueField = "ValueField";

    // Bind the data to the control.
    myDropDown.DataBind();

...

    public ICollection CreateDataSource(MasterData[] colData)
    {
        // Create a table to store data for the DropDownList control.
        DataTable dt = new DataTable();

        // Define the columns of the table.
        dt.Columns.Add(new DataColumn("DescriptionField", typeof(String)));
        dt.Columns.Add(new DataColumn("ValueField", typeof(String)));

        // Populate the table
        foreach (sapMasterData objItem in colData)
        {
            dt.Rows.Add(CreateRow(objItem, dt));
        }

        // Create a DataView from the DataTable to act as the data source 
        // for the DropDownList control.
        DataView dv = new DataView(dt);
        return dv;
    }

    DataRow CreateRow(MasterData objDataItem, DataTable dt)
    {
        // Create a DataRow using the DataTable defined in the  
        // CreateDataSource method.
        DataRow dr = dt.NewRow();

        dr[0] = objDataItem.Description;
        dr[1] = objDataItem.Value;

        return dr;
    }

public class MasterData
{
    public string Value;
    public string Description;
}

Upvotes: 0

Views: 170

Answers (3)

Alex
Alex

Reputation: 23300

A wrapper would do, you have two approaches:

public class WSData
{
    public string Value;
    public string Description;

    // First approach: single ctor with dynamic parameter
    public WSData(dynamic source)
    {
        this.Value = source.Value;
        this.Description = source.Description;
    }

    // ----- or --------

    // Second approach: one ctor for each class
    public WSData(FirstTypeFromWS source)
    {
        this.Value = source.Value;
        this.Description = source.Description;
    }
    public WSData(SecondTypeFromWS source)
    {
        this.Value = source.Value;
        this.Description = source.Description;
    }
}

usage is the same: 

WSData yourData = new WSData(data_retrieved_from_service);
// now, bind the WSData object: you have abstracted yourself from
// the service and as a bonus your code can be attached elsewhere more easily

Upvotes: 1

Andrea Scarcella
Andrea Scarcella

Reputation: 3323

You could define an interface that it is implemented by all four classes (e.g. IDescriptionValue) and write a method that accepts a parameter of that type, for instance:

public interface IDescriptionValue
{
public string Description {get;set;}
public string Value {get;set;}
}

public class CustomClass1 : IDescriptionValue{
public string Description {get;set;}
public string Value {get;set;}
}
//snip...
public class CustomClass4 : IDescriptionValue{
public string Description {get;set;}
public string Value {get;set;}
}
//accepts parameters of type IDescriptionValue
public void setDropdownData(IDescriptionValue inputData){
// your code here
}

Upvotes: 0

Darin Dimitrov
Darin Dimitrov

Reputation: 1038810

Actually the DropDownList control requires you an IEnumerable as DataSource and then you could specify the DataTextField and DataValueField:

dropDownList.DataSource = some_Array_You_Retrieved_From_Your_Web_Service;
dropDownList.DataValueField = "Value";
dropDownList.DataTextField = "Description";
dropDownList.DataBind();

As you can see it doesn't really matter the actual type of the array, as long as it has Value and Description properties to bind it to.

Upvotes: 2

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