Perhaps I'm being dense or missing something simple but I am getting a reference error on this line: json.Converters.Add(new DataRowConverter); The type or namespace name 'DataRowConverter' could not be found (are you missing a using directive or an assembly reference?) And all the other ones below it for DataTable and DataSet. I have downloaded and installed the ASP.NET Futures msi and added that reference to my webservice.

• Outofmemoryexception Sql

An unhandled exception of type 'System.OutOfMemoryException' occurred in Newtonsoft.Json.dll. If I try {'items'. Because a DataSet is a collection of objects. In C# i'm trying to get the xml string from a big DataSet. OutOfMemoryException trying to write Xml from DataSet. DataSet serialization and.

I have also modified my web.config according to the documentation as well as adding some stuff I found on the web. My using statements: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Services; using Newtonsoft.Json; using System.IO; using System.Data; using Microsoft.Web.Preview; Nothing has worked, I am stumped. BTW, I have implemented the same anti-bot scheme as you have (before I saw yours) with the math question and it has worked really well. I haven't had any complaints about the math equation yet.:).

@Howard - deserialization of DataSets would be very difficult to do because the way JSON parsing is typically done is based available type information of the type your are deserializing into. IOW, parsers tend to reflect over the properties that the json provides, figure out the type and then assign the value. DataSets/DataTables/DataRows are untyped so there's no easy way to detect and set the types in the DataRow. You could guess but that's pretty tricky because of the away values are presented and you'd only end up with the few base types that JavaScript supports (string, number, bool and date). None of the parsers out there support this - it can be done but it probably won't yield the results you're looking for anyway because you'd get none of the persistance/change information that datasets normally provide anyway. This is great. 2 things are bugging me though and that is 1) why aren't these converters packaged as part of the JSON.NET library in the first place.

2) I saw somewhere on the web amongst Microsofts ASP sites that you can create classes to represent your rows in the datatable & decorate the properties with something that would make them publishable by the webservice into Json. I can't remember the decoration name, but I think it included the ResponseFormat.Json in the web service. My question is, does MS provide this functionality already without having to use the JSON.NET library? I would have thought that MS would have come up with something since JSON client communication is going to be pretty big. @jono - the main reason I'd guess is because there wouldn't be two way converters.

Converting back from JSON into a DataTable is not really possible without type information available not without a whole separate way to parse the JSON anyway - currently all parsers look at the object structure to figure out type info and then read values from the JSON based on that. Since a serialized data table doesn't include data information and a generic data table doesn't have type information the parsing process would have to guess types based on values (not impossible but completely different approach). Var ds = new Ajax.Web.DataSet; var dt = new Ajax.Web.DataTable; dt.addColumn( 'TownCityID', 'System.Int32'); dt.addColumn( 'PropertyID', 'System.Int32'); dt.addColumn( 'PackageID', 'System.Int32'); dt.addColumn( 'OrderID', 'System.Int32'); ds.addTable(dt); dr = new Object; dr.TownCityID =.; dr.PropertyID =.; dr.PackageID =.; dr.OrderID =.; dt.addRow(dr); var hf = document.getElementById( 'DataSet'); // Get the hidden field to put the JSON into hf.value = AjaxPro.toJSON(ds); var form = document.forms0; form.submit; Then you can deserialize it with. Can anybody point me to an example of this code, or any code that would let me use JSON.NET to serialize a datatable to JSON in a web service, using VB.NET? Every example uses C#, and there's always some part of code that doesn't translate to VB. The guy who wrote the library obviously has no interest in helping anybody actually use it, that's why this post has been so popular, but here again I run into C# syntax that I can't map to VB.NET.

Obviously SerializeObject didn't work - that would have been too easy - and I'm trying to figure out how to make the JSONSerializer work. Something else that is obvious is that I could sit here and scour the internet and eventually figure out how to translate all the C# examples into VB. But I'm almost out of time. I'm just trying to solve a problem and put something to bed. I know I'm totally uncool for using VB and a complete failure as a programmer and a human being. But even loser VB programmers have to make a living, you know? If somebody could just post a quick block showing how to get the datatable serialized to JSON before returning it from a web service, I'm sure Jesus will smile upon you.

Thanks for the kind words Craig. An attitude like that will get you far in life I'm sure. Since you're so nice to me I'll give you a tip for whenever you come across C# code. This is the same process I use when I come across an example in VB.NET: -First I copy the VB.NET/C# into a new Visual Studio project -I compile the the project -I open the new compiled dll in Reflector -And I switch the decompiled code view to my language of choice (VB.NET for you) Baring any deficiencies in the VB.NET language you now you have a working code example. Jagdish, If you read the entire article it explains why it doesn't convert the datatable back - the structure doesn't exist. JSON doesn't provide schema info, so you'd have to guess at the structure of the data table.

Outofmemoryexception Sql

This means something would have to preparse the JSON in order to figure out the DataTable fieldnames first then guessing at the type, and then do an import. Another way this might be approached is to require that the datatable exists before deserializing and using that structure as an input parameter, but that would also change the typical way the deserialization process works and wouldn't be pluggable anymore. In short - JSON deserialization is not something that you should attempt. XML with schema info is much better suited for two way conversions (and DataSets/DataTables) natively support this.

I have copied all the code to one class and when I try to compile I get the following errors: 'DataRowConverter' does not implement inherited abstract member 'Newtonsoft.Json.JsonConverter.ReadJson(Newtonsoft.Json.JsonReader, System.Type, object, Newtonsoft.Json.JsonSerializer)' Error4'DataTableConverter' does not implement inherited abstract member 'Newtonsoft.Json.JsonConverter.CanConvert(System.Type)' and other errors, What am I missing? Thanks in advance (Great article by the way!).

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