当我从Silverlight调用WCF时发生CommunicationException（或者如何在一个函数中从DB中获取所有数据）

Question

I have a question about working with DB using Liqn to SQL.

I have a little database, which includes 4 tables and I have Liq to SQL classes created for this tables: So, It's all created on my AppName. Web project. I'm also created a WPF Service, that returns List collection with all Entries inside. When I just tried to call my function from Silverlight project I've got CommunicationException . I've tried to set maxReceivedMessageSize and maxBufferSize , but problem still appeared. Than I add [DataContract] and [DataMember] tags to auto-generated classes (except properties, that represents references, like Items in Mod table, Recipes and Entries in Item table, etc.) and it started to work, but I can receive only data from one table.

How can I receive List of Mods with all childs in all tables? And is linq to sql one of the best and easiest ways to do it?

UPD1: Functions to return List:

public MCDataClassesDataContext GetContext()
{
    var context = new MCDataClassesDataContext();
    var dlo = new DataLoadOptions();
    dlo.LoadWith<Mod>(p => p.Item);
    dlo.LoadWith<Item>(p => p.Recipe);
    dlo.LoadWith<Item>(p => p.Entry);
    dlo.LoadWith<Recipe>(p => p.Entry);
    context.LoadOptions = dlo;
    return context;
}

public List<Mod> GetMods()
{
    return GetContext().Mod.ToList();
}

Answer 1

CommunicationException is exceptionally broad. Can you create a simple operation on the WCF service to ensure its reachable and that you don't have a configuration / hosting issue?

Alternately turn on WCF message logging and use svctraceviewer to gain better insight to your root cause for the CommunicationException ( http://msdn.microsoft.com/en-us/library/ms730064(v=vs.110).aspx )

Also make sure you're materializing the result of your Linq2Sql query before returning it from the WCF service.

As to choice of object relationship mapper (ORM) Linq2Sql is deprecated in favor of EntityFramework. It still works, but much like the appendix in humans it's an evolutionary dead end.

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After reviewing the stack trace I've been able to determine that WCF is unable to serialize the related types because Linq2Sql is emitting them as dynamic proxies and not as types for which you have marked as data contracts. I would recommend doing a mapping either manually or with something like Automapper which has an effect like this before returning from your service Select(i => new Mod() { Items = i.Items.Select((j) => new Item() { Foo = j.Foo } } });

etc.

One more note: EntityFramework allows the option to turn off dynamic proxies but I don't know if Linq2Sql does. (As a comparison point between the two)