针对MVC非必需的属性整数验证 [英] Integer validation against non-required attributes in MVC

问题描述

我试图验证模型上我有一个属性。此属性不是必需的，所以如果无效MVC似乎忽略它。我甚至创建的自定义ValidationAttribute，但没有任何工程。

I've trying to validate a property on a model I have. This property is NOT required, and so if its invalid MVC seems to be ignoring it. I've even created a custom ValidationAttribute, but nothing works.

public class NumberWang : ValidationAttribute
{
    public override bool IsValid(object value)
    {
        if (value == null)
            return true;

        int g;
        if (int.TryParse(value.ToString(), out g))
        {
            if (g >= 0)
                return true;
        }
        return false;
    }
}

public class MyModel 
{
    [Range(0, 999999, ErrorMessage = "category_id must be a valid number")]
    [NumberWang(ErrorMessage = "That's NumberWang!")]
    public int? category_id { get; set; }

    /* there are other properties of course, but I've omitted them for simplicity */

    public void Validate()
    {
        Validator.TryValidateProperty(this.category_id,
        new ValidationContext(this, null, null) { MemberName = "category_id" },
        this.validation_results);
    }
}

如果我传递值'ABC'作为CATEGORY_ID这个模型，它验证就好了。我究竟做错了什么？

If I pass the value 'abc' as a category_id to this model, it validates just fine. What am I doing wrong?

推荐答案

我发现了一个丑陋的解决方法。

I found an ugly workaround.

看来，如果CATEGORY_ID是一个可空 INT？和我的价值是不是一个有效的数字，一个null值传递，该模型并没有看到无效ABC的价值。

It seems that if category_id is a nullable int? and my value is not a valid number, a null value is passed, and the model doesn't see the invalid 'abc' value.

[Range(0, 999999, ErrorMessage = "category_id must be a valid number")]
public int? category_id { get; set; }

// when we pass a good number
MyAction?category_id=123
validation: successful

// when we pass a bad number
// validation ignores it. not what we want. 
MyAction?category_id=abc
validation: successful

如果我更改为CATEGORY_ID一个非空的 INT ，验证失败，即使没有值传递。

If I change category_id to a non-nullable int, it fails validation even when no value is passed.

[Range(0, 999999, ErrorMessage = "category_id must be a valid number")]
public int? category_id { get; set; }

// when we pass a good number
MyAction?category_id=123
validation: successful

// when we pass an bad number
MyAction?category_id=abc
validation: "category_id must be a valid number"

// BUT, when we don't pass any number at all ... 
MyAction 
validation: "category_id must be a valid number"

丑陋的解决方法

如果我改变CATEGORY_ID到字符串，然后只将它转换为 INT ，当我需要的时候，我可以正确验证它，只用 [范围]

If I change category_id to a string, and then only convert it to an int when I need it, I can validate it properly, using only [Range]

[Range(0, 999999, ErrorMessage = "category_id must be a valid number")]
public string category_id { get; set; }

// when we pass a good number
MyAction?category_id=123
validation: successful

// when we pass a bad number
MyAction?category_id=abc
validation: "category_id must be a valid number"

// no number, no validation. hooray!
MyAction 
validation: successful

这是丑陋的，但它的作品。

It's ugly, but it works.

（注意：没有必要自定义属性，所以我删除它，只是使用[范围]）

(Note: the custom attribute was not needed, so I removed it and just used [Range])

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