Getting Error System.InvalidOperationException When Invoke WebService Method

I had Create One WebService..and Create Get Method inside WebService..
My code is

public class WebService : System.Web.Services.WebService {
DataClassesDataContext db = new DataClassesDataContext();

public WebService ()
{
//Console.log("Enter");
//Uncomment the following line if using designed components
//InitializeComponent();
}

[WebMethod]
public string HelloWorld() {
return "Hello World";
}

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = true)]
public object Get()
{
return db.Countries.ToList();
}
}
But When I am Test Web-service at that I am getting following Error..

System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: The type System.Collections.Generic.List`1[[Country, App_Code.hlnie2jd, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]] may not be used in this context. at System.Xml.Serialization.XmlSerializationWriter.WriteTypedPrimitive(String name, String ns, Object o, Boolean xsiType) at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write1_Object(String n, String ns, Object o, Boolean isNullable, Boolean needType) at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write3_anyType(Object o) at Microsoft.Xml.Serialization.GeneratedAssembly.ObjectSerializer.Serialize(Object objectToSerialize, XmlSerializationWriter writer) at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id) --- End of inner exception stack trace --- at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id) at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o, XmlSerializerNamespaces namespaces) at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o) at System.Web.Services.Protocols.XmlReturnWriter.Write(HttpResponse response, Stream outputStream, Object returnValue) at System.Web.Services.Protocols.HttpServerProtocol.WriteReturns(Object[] returnValues, Stream outputStream) at System.Web.Services.Protocols.WebServiceHandler.WriteReturns(Object[] returnValues) at System.Web.Services.Protocols.WebServiceHandler.Invoke()

any one having solution please help me

Archana Mistry
Sr. Programmer
Kintudesigns.com

2 Replies

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Vulpes14y ago
I have a vague recollection that web services have problems with generic types.

I'd therefore try using an ArrayList instead:

So, replace:

return db.Countries.ToList();

with:

return new System.Collections.ArrayList(db.Countries.ToList());
0
Carl Cioffi14y ago
Were you ever able to solve this problem?

I have the exact same problem but only with CE 5.0 it works fine everywhere else.
0