如何将枚举映射到 class 属性

Question

我有一个包含功能名称的枚举，例如

public enum FeatureNames{
  [Description("Amazing Feature")]
  AmazingFeature,
  [Description("Amazing New Feature")]
  AmazingNewFeature
}

我有一个域实体，它具有表示每个功能的属性，指示该功能是打开还是关闭

public class CompanyAccount{
  public bool IsAmazingFeatureEnabled{get;set;}
  public bool IsAmazingNewFeatureEnabled{get;set;}
}

这就是现有应用程序的编写方式，因此此时我不想对数据库进行重大更改。所以现在我正在尝试编写一个通用方法，该方法将接受一个字符串或枚举值指示功能，并检查是否启用了与相同功能匹配的属性（true 或 false）。

public bool IsEnabled(FeatureNames featureName){
  if(featureName is FeatureNames.AmazingFeature){
    return companyAccount.IsAmazingFeatureEnabled;
  }
  else if(featureName is FeatureNames.AmazingNewFeature){
    return companyAccount.IsAmazingNewFeatureEnabled;
  }

有没有更好的方法来处理这个问题？我们可以避免 if 条件吗？

Answer 1

您可以使用 switch expression (C# 8.0)

public bool IsEnabled(FeatureNames featureName) =>
    featureName switch {
        FeatureNames.AmazingFeature => companyAccount.IsAmazingFeatureEnabled,
        FeatureNames.AmazingNewFeature => companyAccount.IsAmazingNewFeatureEnabled,
        _ => false
    };

或在默认情况下使用 throw expression。

        _ => throw new NotImplementedException($"{featureName} not implemented")

另一种方法是将枚举转换为 flags enum 并添加属性返回状态作为标志集。

[Flags]
public enum FeatureNames {
    None = 0,
    AmazingFeature = 1,
    AmazingNewFeature = 2 // use powers of 2 for all values
}

public class CompanyAccount{
 public bool IsAmazingFeatureEnabled { get; set; }
 public bool IsAmazingNewFeatureEnabled { get; set; }

 public FeatureNames State {
   get {
     var flags = FeatureNames.None;
     if (IsAmazingFeatureEnabled) flags = flags | FeatureNames.AmazingFeature; 
     if (IsAmazingNewFeatureEnabled) flags = flags | FeatureNames.AmazingNewFeature; 
     return flags;
   }
 }
}

然后你可以用

测试状态

if (companyAccount.State.HasFlag(FeatureNames.AmazingFeature)) ...

使用标志枚举，我们可以扭转局面，将状态存储为标志，然后将逻辑放入布尔属性（此处仅显示一个属性）：

private FeatureNames _state;

public bool IsAmazingFeatureEnabled
{
    get => _state.HasFlag(FeatureNames.AmazingFeature);
    set => _state = value 
        ? _state | FeatureNames.AmazingFeature
        : _state & ~FeatureNames.AmazingFeature;
}

如何将枚举映射到 class 属性

How do I map enums to a class property

c#

.net

oop

enums