.net ModelBinder将属性中的现有值转换为null

mklgxw1f  于 2023-02-14  发布在  .NET
关注(0)|答案(1)|浏览(101)

我有一个这样的模型绑定器:

public class CustomQuarantineModelBinder : IModelBinderProvider
{
    public IModelBinder GetBinder(ModelBinderProviderContext context)
    {
        if (context == null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        if (context.Metadata.ModelType.GetInterfaces().Contains(typeof(IQuarantineControl))
        {
            return new QuarantineModelBinder();
        }

        return null;
    }
}

public class QuarantineModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext modelBindingContext)
    {
        char[] delimeter = { '|' };

        if (modelBindingContext == null)
        {
            throw new ArgumentNullException(nameof(modelBindingContext));
        }

        var model = Activator.CreateInstance(modelBindingContext.ModelType);

        if (modelBindingContext.ModelType.GetInterfaces().Contains(typeof(IQuarantineControl)))
        {
            var qc = model as IQuarantineControl;

            if (qc != null)
            {
                var request = modelBindingContext.HttpContext.Request;
                string QuarantineControl = request.Form["QuarantineControl"];

                if (!string.IsNullOrEmpty(QuarantineControl))
                {
                    string[] components = QuarantineControl.Split(delimeter);

                    qc.QuarantineClear();
                    qc.QuarantineControlID = Convert.ToInt32(components[0]);
                    qc.QuarantineState = (QuarantineState)Convert.ToInt32(components[1]);
                    for (int i = 2; i < components.Length; i++)
                    {
                        qc.QuarantineReasons.Add(components[i]);
                    }
                }
            }
        }

        modelBindingContext.Result = ModelBindingResult.Success(model);
        return Task.CompletedTask;
    }

但是,模型中的其他字段将变为null或空。我希望设置QuarantineState、QuarantineControlId等,而不影响其他值。谢谢

yfwxisqw

yfwxisqw1#

当模型对象被发布时,空的字符串值被转换为null。这是MVC模型绑定器的默认行为。您可以尝试这样的解决方案,
公共密封类EmptyStringModelBinder:默认模型绑定器{公共覆盖对象绑定模型(控制器上下文控制器上下文,模型绑定上下文绑定上下文){绑定上下文.模型元数据.将空字符串转换为空= false;//绑定器=新的模型绑定器字典(){默认绑定器=此};返回base.BindModel(控制器上下文,绑定上下文);}}

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