C# CustomAttributeData 类到属性

Question

我有以下代码位于 Swashbuckle.Swagger.IOperationFilter类(class)。

List<CustomAttributeData> controllerAttributes = apiDescription
    .ActionDescriptor
    .ControllerDescriptor
    .ControllerType
    .CustomAttributes
    .Where(a => a.AttributeType == typeof(SwaggerFileInFormDataAttribute))
    .ToList();

我正在成功获取集合。我要转换收藏 List<CustomAttributeData>进入我的自定义属性集合 List<SwaggerFileInFormDataAttribute> .

我想转换 System.Reflection.CustomAttributeData类到我的自定义属性 SwaggerFileInFormDataAttribute .

编辑1:
这是我的 SwaggerFileInFormDataAttribute属性看起来像。

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
public class SwaggerFileInFormDataAttribute : Attribute
{
    private ICollection<string> displayNames;

    public SwaggerFileInFormDataAttribute()
    {
        this.DisplayNames = new List<string> { "File" };
    }

    public SwaggerFileInFormDataAttribute(params string[] displayNames)
    {
        this.DisplayNames = displayNames;
    }

    public ICollection<string> DisplayNames
    {
        get
        {
            if (this.displayNames == null)
                return new List<string> { "File" };
            else
                return this.displayNames;
        }
        set => displayNames = value;
    }
}

成功转换后 List<CustomAttributeData>至 List<SwaggerFileInFormDataAttribute>我将使用类 SwaggerFileInFormDataAttribute 中显示的属性命名 DisplayNames .

Answer 1

第一个解决方案:

List<SwaggerFileInFormDataAttribute> customControllerAttributes = apiDescription
    .ActionDescriptor
    .ControllerDescriptor
    .ControllerType
    .CustomAttributes
    .Where(a => a.AttributeType == typeof(SwaggerFileInFormDataAttribute))
    .Select(a =>
    {
        ReadOnlyCollection<CustomAttributeTypedArgument> costuctorArgumentsReadOnlyCollection = (ReadOnlyCollection<CustomAttributeTypedArgument>)a.ConstructorArguments.Select(x => x.Value).FirstOrDefault();

        string[] contructorParams = costuctorArgumentsReadOnlyCollection?.ToArray().Select(x => x.Value.ToString()).ToArray();
        SwaggerFileInFormDataAttribute myCustomAttr = (SwaggerFileInFormDataAttribute)Activator.CreateInstance(a.AttributeType, contructorParams);
        return myCustomAttr;
    })
    .ToList();

解释:两个变量 costuctorArgumentsReadOnlyCollection和 contructorParams如果所需属性的构造函数为空，则可以跳过。
在这种情况下，只有这一行就足够了: (SwaggerFileInFormDataAttribute)Activator.CreateInstance(a.AttributeType, null);第二种解决方案:
这是一个更清洁的解决方案。我们可以完全跳过 CustomAttributeData IOperationFilter 中的类像那样:

List<SwaggerFileInFormDataAttribute> controllerAttributes = apiDescription
    .ActionDescriptor
    .ControllerDescriptor
    .GetCustomAttributes<SwaggerFileInFormDataAttribute>()
    .ToList();