LINQ错误:<< object>没有无参数的构造函数. [英] LINQ error: "<object> has no parameterless constructor."

问题描述

我有一个如下定义的类方法GetMS()，但是调用该方法时出现错误，指出'SLRD' has no parameterless constructor.，我什至不理解为什么甚至调用了无参数构造函数.怎么了?

I have a class method GetMS() as defined below, but when the method is called I get an error stating 'SLRD' has no parameterless constructor. I don't understand why a parameterless constructor is even being called. What's wrong here?

public class SLR : BaseEntity
{
    // ...
    public virtual ICollection<SLRD> ChildRequests { get; set; }
}

public SLRD GetMS()
{
    return ChildRequests.First(c => c.Type == SLRTypes.MS);
}

推荐答案

您收到的错误非常清楚.您错过了定义无参数构造函数的过程.

The error you get is pretty clear. You missed to define a parameterless constructor.

public class SLR : BaseEntity
{
    public SLR() : base
    {
    }

    // ...
    public virtual ICollection<SLRD> ChildRequests { get; set; }
}

发生这种情况的原因是您的基类可能具有无参数构造函数.因此，您必须为派生类SLR定义一个.

The reason this is happens is the fact that your base class may have a parameterless constructor. So you have to define one for the derived class, SLR.

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