How Can I Validate the Combined Length of Multiple Properties Using Custom Data Annotation in ASP.NET MVC?

Using data annotations for custom validation in ASP.NET MVC

Data annotations in ASP.NET MVC are powerful tools for validating user input. The StringLength attribute allows validating the length of a single string attribute. But what if you need to verify the combined length of multiple properties?

To do this, implement a custom validation attribute.

<code class="language-csharp">public class CombinedMinLengthAttribute : ValidationAttribute
{
    // 构造函数
}

// 方法</code>

In custom attributes:

• PropertyNamesArray holds the attribute names to be combined for length validation.
The
• IsValid overridden method sums the length of the string attributes and compares it to MinLength.

To use custom properties, decorate the properties in your view model as follows:

<code class="language-csharp">public class MyViewModel
{
    [CombinedMinLength(20, "Bar", "Baz", ErrorMessage = "组合长度必须超过20")]
    public string Foo { get; set; }
}</code>

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