可空参数的Web API验证失败 [英] Web api validation on nullable parameter fails

问题描述

我正在尝试验证一种非常简单的方法，并且我得到的值'null'对于Nullable'1错误无效。

I am trying to validate very simple method and I am getting The value 'null' is not valid for Nullable`1 error.

    [ValidateModel]
    public IEnumerable<SomeData> Get(bool? showExtra = null)
    {
        return this.MockDataManager.ShowData(showExtra);
    }

ValidateModel属性为：

ValidateModel property is:

 public override void OnActionExecuting(HttpActionContext actionContext)
    {
        if (actionContext != null && actionContext.ModelState.IsValid == false)
        {
            actionContext.Response = actionContext.Request.CreateErrorResponse(
                HttpStatusCode.BadRequest, actionContext.ModelState);
        }
    }

现在，如果我使用/ true和/调用方法虚假的作品。如果我使用/调用方法，但如果使用/ null调用方法，它也将起作用，但验证失败并显示错误消息 null值对于Nullable`1无效。
如何解决这个问题？

Now, if i call method with /true and /false it works. Also it works if I call method with / but if i call it with /null validation fails and error message The value 'null' is not valid for Nullable`1 appears. How to resolve this?

推荐答案

用/调用是解决方法。

Calling it with / is the way to go. Calling it for /null is not what you want to do.

这是幕后发生的事情：

/false
OK, let's see if I can convert that into a bool. Yes, I can.

/true
OK, let's see if I can convert that into a bool. Yes, I can.

/
OK, let's see if I can convert that into a bool. No, I can't, so use the default
value specified in the method arguments.

/null
OK, let's see if I can convert that into a bool. No, I can't, so throw an
exception.

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