asp.net-mvc 使用 MVC 和数据注释在客户端添加大于 0 验证器的最佳方法是什么？
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What is the best way of adding a greater than 0 validator on the client-side using MVC and data annotation?
提问by jaffa
I'd like to be able to only allow a form to submit if the value in a certain field is greater than 0. I thought maybe the Mvc Range attribute would allow me to enter only 1 value to signify only a greater than test, but no luck there as it insists on Minimum AND Maximum values.
如果某个字段中的值大于 0，我希望能够只允许提交表单。我想也许 Mvc Range 属性允许我只输入 1 个值来表示大于测试，但是没有运气，因为它坚持最小和最大值。
Any ideas how this can be achieved?
任何想法如何实现？
回答by Darin Dimitrov
You can't store a number bigger than what your underlying data type could hold so that fact that the Range attribute requires a max value is a very good thing. Remember that ∞doesn't exist in the real world, so the following should work:
您不能存储大于基础数据类型可以容纳的数字，因此 Range 属性需要最大值的事实是一件非常好的事情。请记住，∞这在现实世界中不存在，因此以下内容应该有效：
[Range(1, int.MaxValue, ErrorMessage = "Please enter a value bigger than {1}")]
public int Value { get; set; }
回答by Phil
I found this answer looking to validate any positive value for a float/double. It turns out these types have a useful constant for 'Epsilon'
我发现这个答案是为了验证浮点/双精度的任何正值。事实证明，这些类型对“Epsilon”有一个有用的常数
Represents the smallest positive System.Double value that is greater than zero.
表示大于零的最小正 System.Double 值。
[Required]
[Range(double.Epsilon, double.MaxValue)]
public double Length { get; set; }
回答by John Lord
You can create your own validator like this:
您可以像这样创建自己的验证器：
public class RequiredGreaterThanZero : ValidationAttribute
{
/// <summary>
/// Designed for dropdowns to ensure that a selection is valid and not the dummy "SELECT" entry
/// </summary>
/// <param name="value">The integer value of the selection</param>
/// <returns>True if value is greater than zero</returns>
public override bool IsValid(object value)
{
// return true if value is a non-null number > 0, otherwise return false
int i;
return value != null && int.TryParse(value.ToString(), out i) && i > 0;
}
}
Then include that file in your model and use it as an attribute like this:
然后将该文件包含在您的模型中，并将其用作这样的属性：
[RequiredGreaterThanZero]
[DisplayName("Driver")]
public int DriverID { get; set; }
I commonly use this on dropdown validation.
我通常在下拉验证中使用它。
