C＃中如何序列化system.linq.ex pressions？ [英] C# How to serialize system.linq.expressions?

问题描述

我在WinRT中和实体框架（到SQL），他们之间通信的层工作的WCF服务。在实体框架我使用存储库模式，我有方法：

I am working on winRT and entity framework (to SQL), the layer that communicates between them is WCF Service. In the entity framework I am using the Repository Pattern and I have the method:

public IQueryable<User> GetBySearch(Expression<Func<User, bool>> search)
{
    return this.Context.Users.Where(search);
}

一切工作正常，但是当我把它添加到WCF

Everything works fine, but when I add it to WCF

[OperationContract]
IQueryable<User> GetUserBySearch(Expression<Func<User, bool>> search);

和

public IQueryable<User> GetUserBySearch(Expression<Func<User, bool>> search)
{
    IUser user = new UserRepository();
    return user.GetBySearch(search);
}

但是，防爆pression不是可序列化的问题，因此，WCF不能序列化。因此，我认为，从它继承并使其[Serializable接口]但问题在于它是一个密封类。

But the problem that Expression is not serializable, therefore, WCF can't serialize it. So I thought to inherit from it and make it [Serializable] but the problem that it is a sealed class.

有人可以帮助我解决这个问题？

Can someone help me to solve the problem?

推荐答案

WCF不与IQueryable的和lambda表达式，如果你使用的是实体框架打好。这是一个快速和肮脏的解决方案，使其适应您的需求。

WCF doesn't play well with Iqueryable and lambdas if your are using Entity Framework. This is a quick and dirty solution, adapt it to your needs.

更改服务合同

[OperationContract]
IEnumerable<User> GetEventBySearch(UserCriteria search);

在哪里UserCriteria是包含一个属性，你需要每一个搜索条件的DataContract - 例如：

Where UserCriteria is a DataContract that contains a property for every search criteria that you need - example:

[DataContract]
public class UserCriteria
{
    [DataMember]
    public string Name { get; set; }

    [DataMember]
    public string Email { get; set; }

    // add a property for each search criteria....
}

服务实现：

public IEnumerable<User> GetEventBySearch(UserCriteria search)
{
    IUser user = new UserRepository();
    Expression<Func<User, bool>> criteria = BuildExpression(search);

    return user.GetBySearch(criteria).AsEnumerable();
}

private Expression<Func<User, bool>> BuildExpression(UserCriteria search)
{
    // build lambda expression here
}

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