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List Converted To Array While Consuming WCF Service

In this article I will state one problem that I experienced when working on WCF service and then discuss its solution.

In WCF if you create a DataMember that is returning a List and use it in the client application (who is consuming the service) then it gets converted into an array. The purpose of this article is to show you how to configure it back to List. I assume that you must be aware of .net and WCF basics so I will not discuss it now.

First of all create a new WCF application with the following ServiceContract and DataContract.

[ServiceContract]
public interface IService1 {

	[OperationContract]
	string GetData(int value);

	[OperationContract]
	List < CompositeType > GetDataUsingDataContract(CompositeType composite);

	// TODO: Add your service operations here
}

// Use a data contract as illustrated in the sample below to add composite types to service operations.
[DataContract]
public class CompositeType {
	bool boolValue = true;
	string stringValue = "Hello ";

	[DataMember]
	public bool BoolValue {
		get {
			return boolValue;
		}
		set {
			boolValue = value;
		}
	}

	[DataMember]
	public string StringValue {
		get {
			return stringValue;
		}
		set {
			stringValue = value;
		}
	}
}

This is the default code generated when you create a WCF application. In the preceding code I have changed the signature of GetDataUsingDataContract method.

And the service will be

public class Service1: IService1 {
	public string GetData(int value) {
		return string.Format("You entered: {0}", value);
	}

	public List < CompositeType > GetDataUsingDataContract(CompositeType composite) {
		return new List < CompositeType > ();
	}
}

Next step is to create a client application who will consume this service. So we have created a console application. As you can see in the following figure list is converted to array when client is consuming the service.

Picture showing the console application code that is consuming the WCF service

Click to Enlarge

Solution

You can right click on the service reference in the client application and click on ‘Configure Service Reference..’ as shown in following figure.

Picture showing the Configure Service Reference option in the context menu of the service reference

Click to Enlarge

A popup appears as shown in following figure. Change the ‘Collection Type’ from ‘System.Array’ to ‘System.Collections.Generic.List’ and click on ‘Ok’.

Picture showing a window to convert collection type from array to List

Click to Enlarge

Now when you call the service method you could see the list as return type instead of array.

Picture showing the output of the List converted to array while consuming WCF service

Click to Enlarge

Posted By -	Karan Gupta

Posted On -	Friday, May 15, 2015

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