Returning results from DLinq query in Webservice

  • Thread starter Thread starter Andrus
  • Start date Start date
A

Andrus

I need to return results of anon DLinq query from ASMX Web service.

I tried code below but in this case web service call does not return any
properties.
How to fix ?

Andrus.

[WebService]
public sealed class StockService {

[WebMethod]
public object[] GetProductList(string table, int pageNumber, int
itemsPerPage, string filter, string sortBy, out int totalCount)
{
using (var db = new Database())
{

swithch (Table) {
case "Customer":
totalCount = db.Customer.Count();

var l =
db.Customer.Skip(pageNumber*itemsPerPage).Take(itemsPerPage ).
Select((c) => new { c.Id, c.Name}).ToArray();
return l;

case "Product":
totalCount = db.Product.Count();
var l =
db.Product.Skip(pageNumber*itemsPerPage).Take(itemsPerPage ).
Select((p) => new { p.Id, p.Name, p.Address}).ToArray();
return l;
}
}
}
}
 
The problem is that you are returning object[] which has no properties to
return. If this is WCF you can add a ServiceKnownType attribute to the
interface's method; but it looks to me like a standard webservice in which
case you should create two methods, one for Customer and one for Product
which return Customer[] and Product[] respectively.
 
Peter,

thank you.
The problem is that you are returning object[] which has no properties to
return. If this is WCF you can add a ServiceKnownType attribute to the
interface's method; but it looks to me like a standard webservice in which
case you should create two methods, one for Customer and one for Product
which return Customer[] and Product[] respectively.
Click to expand...

I'm sorry, my code was too simplified.
In real method return property names are not known at design time: user can
select at runtime which columns she wants to
see.
So I must create single generic method.
How to implement this ?
Is it possible/reasonable to convert result from List<TAnonymuous> to
List<Dictionary<string,object>>
so that any property list can serialized and returned as dictionary from
WebService ?

Andrus.
 
If the client is a .NET one you could return a DataSet. If it's not you
could return an XML string. If you switch to WCF you can list lots of
ServiceKnownType and return all kinds of things.
 
Peter,

thank you.
If the client is a .NET one you could return a DataSet. If it's not you
could return an XML string. If you switch to WCF you can list lots of
ServiceKnownType and return all kinds of things.
Click to expand...

Client is SliverLight 2 applicaton. SL does not support DataSet so it is not
possible.
I'm planning to use MONO as server. MONO does not support WCF services so
this is also impossible.
I have code which can use Dictionary list in SilverLight application.
So it may be best to create Dictonary list from XMLin SL.

So there are two solutions:

1. Convert List<TAnonymuous> to XML format which can then converted to
dictionary in Silverlight client.
2. Convert List<TAnonymuous> to Dictionary list.
Hopefully ASMX service can serialize and return this list.

Where to find sample code for those solutions ?

Andrus.
 
At a place I am contracting for we are returning data transfer objects. One
of the guys converted Hessian to work with SilverLight. If you email me
directly I will ask for permission to let you have it if you'd like?
 
Peter,

I resolved this issue by changing my Web method signature to

public List<object[]> GetProductList(int pageNumber, int itemsPerPage,
string filter, string sortBy, out int totalProductCount, out string[]
columnName)
{}

And creating Dictionary in Silverlight client side:

public IEnumerable<IDictionary> GenerateData(string[] column, object[][]
result) {
for (var i = 0; i < result.GetLength(0); i++) {
var dict = new Dictionary<string, object>();
for (int j = 0; j < column.Length; j++)
dict[column[j]] = result[j];
yield return dict;
}
}

....
//http://devinfra-us.blogspot.com/2008/07/agdatagrid-and-silverlight-datagrid-how.html
InventoryList.DataSource = GenerateData(e.columnName,
e.Result).ToDataSource();

I'm using Bodurow excellent ToDataSource() method.

I'm interesting on looking to other free and open source solutions.

What is Hessian and how to use it ?

Andrus Moor
 
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