C#•2y ago

❔ ✅ How to get attributes values?

I have following property with custom attribute [CatalogComponent]:

[CatalogComponent]                                              
[JsonProperty( PropertyName = "event_categories" )]             
public HashSet<EventCategoryType>? EventCategories { get; set; }

[CatalogComponent]                                              
[JsonProperty( PropertyName = "event_categories" )]             
public HashSet<EventCategoryType>? EventCategories { get; set; }

EventCategoryType is enum:

public enum EventCategoryType
{
[EnumMember( Value = "undefined" )]
Undefined,

[EnumMember( Value = "diagnostics" )]
[TitleLocalized( typeof( Resources.EventCategoryTypeTitle ) )]
[DescriptionLocalized( typeof( Resources.EventCategoryTypeDescription ) )]
Diagnostics,

[EnumMember( Value = "warning" )]
[TitleLocalized( typeof( Resources.EventCategoryTypeTitle ) )]
[DescriptionLocalized( typeof( Resources.EventCategoryTypeDescription ) )]
Warning
}

public enum EventCategoryType
{
[EnumMember( Value = "undefined" )]
Undefined,

[EnumMember( Value = "diagnostics" )]
[TitleLocalized( typeof( Resources.EventCategoryTypeTitle ) )]
[DescriptionLocalized( typeof( Resources.EventCategoryTypeDescription ) )]
Diagnostics,

[EnumMember( Value = "warning" )]
[TitleLocalized( typeof( Resources.EventCategoryTypeTitle ) )]
[DescriptionLocalized( typeof( Resources.EventCategoryTypeDescription ) )]
Warning
}

So my question is it possible to get EnumMember value and TitleLocalized value from EventCategoryType in custom attribute?

11 Replies

FestivalDelGelato•2y ago

using reflection, sure

SWEETPONYOP•2y ago

okay, let's see we have this property:

[CatalogComponent]                                              
[JsonProperty( PropertyName = "event_categories" )]             
public HashSet<T>? EventCategories { get; set; }

[CatalogComponent]                                              
[JsonProperty( PropertyName = "event_categories" )]             
public HashSet<T>? EventCategories { get; set; }

how can I get T in CatalogComponent?

FestivalDelGelato•2y ago

wait is it generic or is it EventCategoryTypes

SWEETPONYOP•2y ago

[CatalogComponent]                                              
public HashSet<A>? EventCategories { get; set; }

[CatalogComponent]                                              
public HashSet<B>? EventCategories { get; set; }

[CatalogComponent]                                              
public HashSet<C>? EventCategories { get; set; }

[CatalogComponent]                                              
public HashSet<A>? EventCategories { get; set; }

[CatalogComponent]                                              
public HashSet<B>? EventCategories { get; set; }

[CatalogComponent]                                              
public HashSet<C>? EventCategories { get; set; }

different types but A, B, C will have EnumMember and TitleLocalized

FestivalDelGelato•2y ago

anyway to get T you look into GetType() probably it would be GenericTypeArgument

SWEETPONYOP•2y ago

[CatalogComponent<EventCategoryType>]                            
[JsonProperty( PropertyName = "event_categories" )]              
public HashSet<EventCategoryType>? EventCategories { get; set; } 

public class CatalogComponentAttribute<T> : Attribute
{
}

[CatalogComponent<EventCategoryType>]                            
[JsonProperty( PropertyName = "event_categories" )]              
public HashSet<EventCategoryType>? EventCategories { get; set; } 

public class CatalogComponentAttribute<T> : Attribute
{
}

I can do this..

FestivalDelGelato•2y ago

for the attributes, you have to search into Field for GetCustomAttribute

SWEETPONYOP•2y ago

hm I will try smth like that..?

static private string GetEnumMemberValue()                        
    => typeof(T).GetCustomAttribute<EnumMemberAttribute>()?.Value;

static private string GetEnumMemberValue()                        
    => typeof(T).GetCustomAttribute<EnumMemberAttribute>()?.Value;

[CatalogComponent<EventCategoryType>]                           
[JsonProperty( PropertyName = "event_categories" )]             
public HashSet<EventCategoryType>? EventCategories { get; set; }

public class CatalogComponentAttribute<T> : Attribute           
{                                                               
    public InputType InputType =>                               
        InputType.Catalog;                                      
                                                                
    public string? EnumMemberValue =>                           
        typeof(T).GetCustomAttribute<EnumMemberAttribute>()?     
            .Value;                                              
                                                                
    public string? TitleLocalizedValue =>                       
        typeof(T).GetCustomAttribute<TitleLocalizedAttribute>()?
            .Value;                                              
}

[CatalogComponent<EventCategoryType>]                           
[JsonProperty( PropertyName = "event_categories" )]             
public HashSet<EventCategoryType>? EventCategories { get; set; }

public class CatalogComponentAttribute<T> : Attribute           
{                                                               
    public InputType InputType =>                               
        InputType.Catalog;                                      
                                                                
    public string? EnumMemberValue =>                           
        typeof(T).GetCustomAttribute<EnumMemberAttribute>()?     
            .Value;                                              
                                                                
    public string? TitleLocalizedValue =>                       
        typeof(T).GetCustomAttribute<TitleLocalizedAttribute>()?
            .Value;                                              
}

is it good solution?

FestivalDelGelato•2y ago

this is, generically, the part that would check the attribute of an enum one way to do it

[AttributeUsage(AttributeTargets.Enum | AttributeTargets.Field)] class TestAttribute : Attribute { }
enum TestEnum { [Test]TestValue }

var enumValue = TestEnum.TestValue;
var valueType = enumValue.GetType();
string valueName = enumValue.ToString();
var valueField = valueType.GetField(valueName);
var valueAttr = valueField.GetCustomAttribute(typeof(TestAttribute), false);

[AttributeUsage(AttributeTargets.Enum | AttributeTargets.Field)] class TestAttribute : Attribute { }
enum TestEnum { [Test]TestValue }

var enumValue = TestEnum.TestValue;
var valueType = enumValue.GetType();
string valueName = enumValue.ToString();
var valueField = valueType.GetField(valueName);
var valueAttr = valueField.GetCustomAttribute(typeof(TestAttribute), false);

so there's a step in between, GetField sadly it's not the easiest thing to do anyway you can inspect GetType() and look around for what you need

SWEETPONYOP•2y ago

okay, I see I did this and it works well:

public class CatalogComponentAttribute<T> : Attribute                                 
{                                                                                     
    public InputType InputType =>                                                     
        InputType.Catalog;                                                            
                                                                                      
    public IEnumerable<(string? title, string? enumMember)> LocalizedValues =>        
        typeof(T)                                                                     
            .GetProperties()                                                          
            .Select(property => (                                                     
                title: property.GetCustomAttribute<TitleLocalizedAttribute>()?.Value, 
                enumMember: property.GetCustomAttribute<EnumMemberAttribute>()?.Value 
            ));                                                                        
}

public class CatalogComponentAttribute<T> : Attribute                                 
{                                                                                     
    public InputType InputType =>                                                     
        InputType.Catalog;                                                            
                                                                                      
    public IEnumerable<(string? title, string? enumMember)> LocalizedValues =>        
        typeof(T)                                                                     
            .GetProperties()                                                          
            .Select(property => (                                                     
                title: property.GetCustomAttribute<TitleLocalizedAttribute>()?.Value, 
                enumMember: property.GetCustomAttribute<EnumMemberAttribute>()?.Value 
            ));                                                                        
}

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ ✅ How to get attributes values?

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