How to return a multi-dimensional array from a web service method?

Question

[WebMethod]
public Object GetAllItemsArray() 
{
 FoodCityData.ShoppingBuddyEntities fdContext = new FoodCityData.ShoppingBuddyEntities();
 IQueryable<Item> Query =
 from c in fdContext.Item
 select c;
 List<Item> AllfNames = Query.ToList();
 int arrayZise = AllfNames.Count;
 String[,] xx = new String[arrayZise,2];
 int i = 0;
 int j = 0;
 foreach(Item x in AllfNames)
 {
 xx[i,0] = x.ItemName.ToString();
 xx[i, 1] = x.ItemPrice.ToString();
 i++;
 }
 return (Object)xx;
 }

I want to return a multi-dimensional array from this web service how do I do it?

This code gives a error

Actually this web service is calling from android application that's why I return this data as a multi-dimensional array..

Error IS:

System.InvalidOperationException: There was an error generating the XML document. ---> System.NotSupportedException: Cannot serialize object of type System.String[,]. Multidimensional arrays are not supported.
 at System.Xml.Serialization.TypeDesc.CheckSupported()
 at System.Xml.Serialization.TypeScope.GetTypeDesc(Type type, MemberInfo source, Boolean directReference, Boolean throwOnError)
 at System.Xml.Serialization.XmlSerializationWriter.CreateUnknownTypeException(Type type)
 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.Write5_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()

• marc_s: WHAT error are you getting?!?! We can't read your screen nor your mind - you'll have to tell us!
• CodeCaster: Why a multy diamentol arry and not just serialize objects?
• Gayashan: no im using KSOP2, i dont know how to call for web services using JSON
• CodeCaster: I meant why do you want to use arrays, when you can easily serialize objects?
• Gayashan: @codeCaster can you please how do i do it?

Answer 1

Based on your previous question and the errror you specify in comments under the answer, I believe you should return a Jagged Array something like:

[WebMethod]
public string[][] GetAllItemsArray() 
{
 FoodCityData.ShoppingBuddyEntities fdContext = new FoodCityData.ShoppingBuddyEntities();
 IQueryable<Item> Query =
 from c in fdContext.Item
 select c;
 List<Item> AllfNames = Query.ToList();
 int arrayZise = AllfNames.Count;
 String[][] xx = new String[arrayZise][2]; //change here
 int i = 0;
 int j = 0;
 foreach(Item x in AllfNames)
 {
 xx[i][0] = x.ItemName.ToString();
 xx[i][1] = x.ItemPrice.ToString();
 i++;
 }
 return xx;
 }

• Gayashan: Invalid rank specifier: expected ',' or ']' im getting this error when i changed code to String[,] xx = new String[arrayZise][2]
• Habib: @Gayashan, my bad, forgot to modify the declaration it should be String[][] xx, edited my answer

Answer 2

You have the answer in your question exception - Multidimensional arrays are not supported. at System.Xml.Serialization. You have to return it in some different way - Jagged Array or write your own Serializer.

• Gayashan: I dont know any other ways, if you know some other way can you help me?
• Alex: Well, there are many examples over internet. See social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/… so see how to make your own serializer, or simply change your String[,] to String[][] and return it in your method

Answer 3

I had the same problem, a year later but I looked for several solutions and if you want to return JSON or XML then you just need to invoke a serializer. I created a Dictionary object and was returning this. It worked fine in a web page but not for a web service. So after a little hunting I found this Json Object serializer. I just had to pass my object into JsonConvert(SerializeObject) and whalla JSON comes back and the web service works! This is a terrific package: http://james.newtonking.com/json.