I have a class that includes several hundred Properties. Each of the properties was declared with a [CategoryAttribute("My Category Name")] attribute clause so that it will display nicely in a PropertyGrid. I would like to make use of this same CategoryAttribute attribute to set the values of all the properties in the class that were labeled with specific categoryAttribute catagories. The code below compiles and runs but it doesn't accomplish the task because att_coll doesn't contain the CategoryAttribute attribute that I expected that it would. Does anyone know how to do this? Thanks so much.
class my_class
{
[CategoryAttribute("Category One")]
public int property_1
{
get { return _property_1; }
set { _property_1 = value; }
}
[CategoryAttribute("Category One")]
public int property_2
{
get { return _property_2; }
set { _property_2 = value; }
}
}
void ClearCatagory(string category_name)
{
CategoryAttribute target_attribute = new CategoryAttribute(category_name);
Type my_class_type = my_class.GetType();
PropertyInfo[] prop_info_array = my_class_type.GetProperties();
foreach (PropertyInfo prop_info in prop_info_array)
{
AttributeCollection att_coll = TypeDescriptor.GetAttributes(prop_info);
CategoryAttribute ca = (CategoryAttribute) att_col[typeof(CategoryAttribute)];
if (ca.Equals(target_attribute))
{
prop_info.SetValue(my_class, 0, null);
}
}
}
Use the MemberInfo.GetCustomAttributes instance method instead of TypeDescriptor.GetAttriburtes.
The call would be object[] attributes = prop_info.GetCustomAttributes(typeof(CategoryAttriute), false).
Or you could use TypeDescriptor.GetProperties instead of Type.GetProperties You shouldn't switch between using reflection and TypeDescriptor.
Also, the documentation for Category.Equals isn't exactly clear, but likely it implements reference equality (which is the default for C# unless a class specifically overrides it). Which means that Equals will only return true if the instances being compared are exactly the same regardless of the value of Category. If that is the case, then ca.Equals(target_attribute) will always be false because the references are different objects.
Try instead comparing the string value stored in the Category value. Strings implement value equality so that String.Equals compares the values stored in the stings.
So replace
if (ca.Equals(target_attribute))
with
if (ca.Cateogry.Equals(category_name))
Thanks so much to shf301 for solving this. Here is a working version of the code:
class my_class
{
[CategoryAttribute("Category One")]
public int property_1
{
get { return _property_1; }
set { _property_1 = value; }
}
}
void ClearCatagory(string category_name)
{
Type my_class_type = my_class.GetType();
PropertyInfo[] prop_info_array = my_class_type.GetProperties();
foreach (PropertyInfo prop_info in prop_info_array)
{
CategoryAttribute[] attributes = (CategoryAttribute[]) prop_info.GetCustomAttributes(typeof(CategoryAttribute), false);
foreach(CategoryAttribute ca in attributes)
{
if (ca.Category == category_name)
{
prop_info.SetValue(my_class, 0, null);
}
}
}
}
public class cls
{
[Category("Default")]
[DisplayName("Street")]
public string Street { get; set; }
}
foreach (PropertyInfo propinf in cls.GetProperties())
{
var category = prop.CustomAttributes.Where(x => x.AttributeType ==typeof(CategoryAttribute)).First();
sCategory = category.ConstructorArguments[0].Value.ToString();
}
This is how we could get value of CustomAttribute
I have recently started a development in c# and want to use reflection in following situation.
If I have a Enum class as
Enum Operation
{
Read=0;
Write;
}
If I give input as
String str = "Operation.Write";
I shoud be able to get output as 1;
Or
if constants are defined like
const int Read=0;
const int Write=1;
If the input is
String str = "Read";
output should be 0
Please Help.
You can use Enum.Parse to have that functionality.
If we combine your proposals we can get something like this.
public static Operation getOperationByName(String name) {
return Enum.Parse(typeof(Operation),name);
}
Where the name should not be null and represent the name or position in enum ie
"Read" will return Operation.Rerad and "1" will return Operation.Write
Heres the complete code to also Get the type of the Enum through Reflection without hardcoding it. The ParseConstant Method is also generic, s.t. you can use if for every Type.
namespace MyNamgespace
{
public enum Operation
{
Read = 0,
Write
}
public class ClassWithConstants
{
public const int Read = 0;
public const int Write = 1;
}
internal class Program
{
static void Main(string[] args)
{
Console.WriteLine((ParseEnum("Operation.Write")));
Console.WriteLine((ParseContant<ClassWithConstants>("Write")));
Console.ReadLine();
}
static int ParseEnum(string enumValue)
{
var typeName = enumValue.Split('.')[0];
var valueName = enumValue.Split('.')[1];
var enumType = Type.GetType(string.Format("MyNamespace.{0}", typeName));
var op = (Operation) Enum.Parse(enumType, valueName);
return (int)op;
}
static int ParseContant<T>(string constantName)
{
var type = typeof (T);
var field = type.GetField(constantName, BindingFlags.Static | BindingFlags.Public);
return (int)field.GetValue(null);
}
}
}
var name = Enum.GetName(typeof(Operation), Operation.Write) //name = 'Write'
var value = Enum.Parse(typeof(Operation), "Write") //value = Operation.Write
I have an attribute and i want to load text to the attribute from a resource file.
[IntegerValidation(1, 70, ErrorMessage = Data.Messages.Speed)]
private int i_Speed;
But I keep getting
"An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type"
It works perfectly if i add a string instead of Data.Messages.Text, like:
[IntegerValidation(1, 70, ErrorMessage = "Invalid max speed")]
Any ideas?
Here is my solution. I've added resourceName and resourceType properties to attribute, like microsoft has done in DataAnnotations.
public class CustomAttribute : Attribute
{
public CustomAttribute(Type resourceType, string resourceName)
{
Message = ResourceHelper.GetResourceLookup(resourceType, resourceName);
}
public string Message { get; set; }
}
public class ResourceHelper
{
public static string GetResourceLookup(Type resourceType, string resourceName)
{
if ((resourceType != null) && (resourceName != null))
{
PropertyInfo property = resourceType.GetProperty(resourceName, BindingFlags.Public | BindingFlags.Static);
if (property == null)
{
throw new InvalidOperationException(string.Format("Resource Type Does Not Have Property"));
}
if (property.PropertyType != typeof(string))
{
throw new InvalidOperationException(string.Format("Resource Property is Not String Type"));
}
return (string)property.GetValue(null, null);
}
return null;
}
}
Attribute values are hard-coded into the assembly when you compile. If you want to do anything at execution time, you'll need to use a constant as the key, then put some code into the attribute class itself to load the resource.
Here is the modified version of the one I put together:
[System.AttributeUsage(System.AttributeTargets.Class, AllowMultiple = false)]
public class ProviderIconAttribute : Attribute
{
public Image ProviderIcon { get; protected set; }
public ProviderIconAttribute(Type resourceType, string resourceName)
{
var value = ResourceHelper.GetResourceLookup<Image>(resourceType, resourceName);
this.ProviderIcon = value;
}
}
//From http://stackoverflow.com/questions/1150874/c-sharp-attribute-text-from-resource-file
//Only thing I changed was adding NonPublic to binding flags since our images come from other dll's
// and making it generic, as the original only supports strings
public class ResourceHelper
{
public static T GetResourceLookup<T>(Type resourceType, string resourceName)
{
if ((resourceType != null) && (resourceName != null))
{
PropertyInfo property = resourceType.GetProperty(resourceName, BindingFlags.Public | BindingFlags.Static | BindingFlags.NonPublic);
if (property == null)
{
return default(T);
}
return (T)property.GetValue(null, null);
}
return default(T);
}
}
I came across this problem with the display name for attribute, and I made the following changes:
For our resource file I changed the custom tool property to PublicResXFileCodeGenerator
Then added this to the attribute:
[Display(Name = "MyResourceName", ResourceType = typeof(Resources.MyResources))]
If you're using .NET 3.5 or newer you can use ErrorMessageResourceName and ErrorMessageResourceType parameters.
For example
[Required(ErrorMessageResourceName ="attribute_name" , ErrorMessageResourceType = typeof(resource_file_type))]
Use a string which is the name of the resource. .NET does this with some internal attributes.
The nature of attributes is such that the data you put in attribute properties must be constants. These values will be stored within an assembly, but will never result in compiled code that is executed. Thus you cannot have attribute values that rely on being executed in order to calculate the results.
I have a similar case, where I need to put resource strings into attributes. In C# 6, we have the nameof() capability, and that seems to do the trick.
In my case, I can use [SomeAttribute(nameof(Resources.SomeResourceKey))] and it compiles fine. Then I just have to do a little work on the other end to use that value to get the correct string from the Resources file.
In your case, you might try:
[IntegerValidation(1, 70, ErrorMessageResourceKey = nameof(Data.Messages.Speed))]
private int i_Speed;
Then you can do something along the lines of (pseudo code):
Properties.Resources.ResourceManager.GetString(attribute.ErrorMessageResourceKey);
Here's something I wrote since I couldn't find anything else that does this.:
Input
Write a constant string class in project A.
[GenerateResource]
public static class ResourceFileName
{
public static class ThisSupports
{
public static class NestedClasses
{
[Comment("Comment value")]
public const string ResourceKey = "Resource Value";
}
}
}
Output
And a resource will be generated in the project that contains the constants class.
All you need to do is have this code somewhere:
Source
public class CommentAttribute : Attribute
{
public CommentAttribute(string comment)
{
this.Comment = comment;
}
public string Comment { get; set; }
}
public class GenerateResourceAttribute : Attribute
{
public string FileName { get; set; }
}
public class ResourceGenerator
{
public ResourceGenerator(IEnumerable<Assembly> assemblies)
{
// Loop over the provided assemblies.
foreach (var assembly in assemblies)
{
// Loop over each type in the assembly.
foreach (var type in assembly.GetTypes())
{
// See if the type has the GenerateResource attribute.
var attribute = type.GetCustomAttribute<GenerateResourceAttribute>(false);
if (attribute != null)
{
// If so determine the output directory. First assume it's the current directory.
var outputDirectory = Directory.GetCurrentDirectory();
// Is this assembly part of the output directory?
var index = outputDirectory.LastIndexOf(typeof(ResourceGenerator).Assembly.GetName().Name);
if (index >= 0)
{
// If so remove it and anything after it.
outputDirectory = outputDirectory.Substring(0, index);
// Is the concatenation of the output directory and the target assembly name not a directory?
outputDirectory = Path.Combine(outputDirectory, type.Assembly.GetName().Name);
if (!Directory.Exists(outputDirectory))
{
// If that is the case make it the current directory.
outputDirectory = Directory.GetCurrentDirectory();
}
}
// Use the default file name (Type + "Resources") if one was not provided.
var fileName = attribute.FileName;
if (fileName == null)
{
fileName = type.Name + "Resources";
}
// Add .resx to the end of the file name.
fileName = Path.Combine(outputDirectory, fileName);
if (!fileName.EndsWith(".resx", StringComparison.InvariantCultureIgnoreCase))
{
fileName += ".resx";
}
using (var resx = new ResXResourceWriter(fileName))
{
var tuples = this.GetTuplesRecursive("", type).OrderBy(t => t.Item1);
foreach (var tuple in tuples)
{
var key = tuple.Item1 + tuple.Item2.Name;
var value = tuple.Item2.GetValue(null);
string comment = null;
var commentAttribute = tuple.Item2.GetCustomAttribute<CommentAttribute>();
if (commentAttribute != null)
{
comment = commentAttribute.Comment;
}
resx.AddResource(new ResXDataNode(key, value) { Comment = comment });
}
}
}
}
}
}
private IEnumerable<Tuple<string, FieldInfo>> GetTuplesRecursive(string prefix, Type type)
{
// Get the properties for the current type.
foreach (var field in type.GetFields(BindingFlags.Public | BindingFlags.Static))
{
yield return new Tuple<string, FieldInfo>(prefix, field);
}
// Get the properties for each child type.
foreach (var nestedType in type.GetNestedTypes())
{
foreach (var tuple in this.GetTuplesRecursive(prefix + nestedType.Name, nestedType))
{
yield return tuple;
}
}
}
}
And then make a small project that has a reference to all your assemblies with [GenerateResource]
public class Program
{
static void Main(string[] args)
{
var assemblies = AppDomain.CurrentDomain.GetAssemblies().ToList();
string path = Directory.GetCurrentDirectory();
foreach (string dll in Directory.GetFiles(path, "*.dll"))
{
assemblies.Add(Assembly.LoadFile(dll));
}
assemblies = assemblies.Distinct().ToList();
new ResourceGenerator(assemblies);
}
}
Then your attributes can use the static class ResourceFileName.ThisSupports.NestedClasses.ResourceKey while other code can use the resource file.
You might need to tailor it to your specific needs.
I would like to get property name when I'm in it via reflection. Is it possible?
I have code like this:
public CarType Car
{
get { return (Wheel) this["Wheel"];}
set { this["Wheel"] = value; }
}
And because I need more properties like this I would like to do something like this:
public CarType Car
{
get { return (Wheel) this[GetThisPropertyName()];}
set { this[GetThisPropertyName()] = value; }
}
Since properties are really just methods you can do this and clean up the get_ returned:
class Program
{
static void Main(string[] args)
{
Program p = new Program();
var x = p.Something;
Console.ReadLine();
}
public string Something
{
get
{
return MethodBase.GetCurrentMethod().Name;
}
}
}
If you profile the performance you should find MethodBase.GetCurrentMethod() is miles faster than StackFrame. In .NET 1.1 you will also have issues with StackFrame in release mode (from memory I think I found it was 3x faster).
That said I'm sure the performance issue won't cause too much of a problem- though an interesting discussion on StackFrame slowness can be found here.
I guess another option if you were concerned about performance would be to create a Visual Studio Intellisense Code Snippet that creates the property for you and also creates a string that corresponds to the property name.
Slightly confusing example you presented, unless I just don't get it.
From C# 6.0 you can use the nameof operator.
public CarType MyProperty
{
get { return (CarType)this[nameof(MyProperty)]};
set { this[nameof(MyProperty)] = value]};
}
If you have a method that handles your getter/setter anyway, you can use the C# 4.5 CallerMemberName attribute, in this case you don't even need to repeat the name.
public CarType MyProperty
{
get { return Get<CarType>(); }
set { Set(value); }
}
public T Get<T>([CallerMemberName]string name = null)
{
return (T)this[name];
}
public void Set<T>(T value, [CallerMemberName]string name = null)
{
this[name] = value;
}
I'd like to know more about the context in which you need it since it seems to me that you should already know what property you are working with in the property accessor. If you must, though, you could probably use MethodBase.GetCurrentMethod().Name and remove anything after get_/set_.
Update:
Based on your changes, I would say that you should use inheritance rather than reflection. I don't know what data is in your dictionary, but it seems to me that you really want to have different Car classes, say Sedan, Roadster, Buggy, StationWagon, not keep the type in a local variable. Then you would have implementations of methods that do the proper thing for that type of Car. Instead of finding out what kind of car you have, then doing something, you then simply call the appropriate method and the Car object does the right thing based on what type it is.
public interface ICar
{
void Drive( decimal velocity, Orientation orientation );
void Shift( int gear );
...
}
public abstract class Car : ICar
{
public virtual void Drive( decimal velocity, Orientation orientation )
{
...some default implementation...
}
public abstract void Shift( int gear );
...
}
public class AutomaticTransmission : Car
{
public override void Shift( int gear )
{
...some specific implementation...
}
}
public class ManualTransmission : Car
{
public override void Shift( int gear )
{
...some specific implementation...
}
}
Use MethodBase.GetCurrentMethod() instead!
Reflection is used to do work with types that can't be done at compile time. Getting the name of the property accessor you're in can be decided at compile time so you probably shouldn't use reflection for it.
You get use the accessor method's name from the call stack using System.Diagnostics.StackTrace though.
string GetPropertyName()
{
StackTrace callStackTrace = new StackTrace();
StackFrame propertyFrame = callStackTrace.GetFrame(1); // 1: below GetPropertyName frame
string properyAccessorName = propertyFrame.GetMethod().Name;
return properyAccessorName.Replace("get_","").Replace("set_","");
}
FWIW I implemented a system like this:
[CrmAttribute("firstname")]
public string FirstName
{
get { return GetPropValue<string>(MethodBase.GetCurrentMethod().Name); }
set { SetPropValue(MethodBase.GetCurrentMethod().Name, value); }
}
// this is in a base class, skipped that bit for clairty
public T GetPropValue<T>(string propName)
{
propName = propName.Replace("get_", "").Replace("set_", "");
string attributeName = GetCrmAttributeName(propName);
return GetAttributeValue<T>(attributeName);
}
public void SetPropValue(string propName, object value)
{
propName = propName.Replace("get_", "").Replace("set_", "");
string attributeName = GetCrmAttributeName(propName);
SetAttributeValue(attributeName, value);
}
private static Dictionary<string, string> PropToAttributeMap = new Dictionary<string, string>();
private string GetCrmAttributeName(string propertyName)
{
// keyName for our propertyName to (static) CrmAttributeName cache
string keyName = this.GetType().Name + propertyName;
// have we already done this mapping?
if (!PropToAttributeMap.ContainsKey(keyName))
{
Type t = this.GetType();
PropertyInfo info = t.GetProperty(propertyName);
if (info == null)
{
throw new Exception("Cannot find a propety called " + propertyName);
}
object[] attrs = info.GetCustomAttributes(false);
foreach (object o in attrs)
{
CrmAttributeAttribute attr = o as CrmAttributeAttribute ;
if (attr != null)
{
// found it. Save the mapping for next time.
PropToAttributeMap[keyName] = attr.AttributeName;
return attr.AttributeName;
}
}
throw new Exception("Missing MemberOf attribute for " + info.Name + "." + propertyName + ". Could not auto-access value");
}
// return the existing mapping
string result = PropToAttributeMap[keyName];
return result;
}
There's also a custom attribute class called CrmAttributeAttribute.
I'd strongly recommend against using GetStackFrame() as part of your solution, my original version of the solution was originally the much neater:
return GetPropValue<string>();
But it was 600x slower than the version above.
Solution # 1
var a = nameof(SampleMethod); //a == SampleMethod
var b = nameof(SampleVariable); //b == SampleVariable
var c = nameof(SampleProperty); //c == SampleProperty
Solution # 2
MethodBase.GetCurrentMethod().Name; // Name of method in which you call the code
MethodBase.GetCurrentMethod().Name.Replace("set_", "").Replace("get_", ""); // current Property
Solution # 3
from StackTrace:
public static class Props
{
public static string CurrPropName =>
(new StackTrace()).GetFrame(1).GetMethod().Name.Replace("set_", "").Replace("get_", "");
public static string CurrMethodName =>
(new StackTrace()).GetFrame(1).GetMethod().Name;
}
you just need to call Props.CurrPropName or Props.CurrMethodName
Solution # 4
Solution for .NET 4.5+:
public static class Props
{
public static string GetCallerName([System.Runtime.CompilerServices.CallerMemberName] String propertyName = "")
{
return propertyName;
}
}
usage: Props.GetCallerName();
Yes, it is!
string test = "test string";
Type type = test.GetType();
PropertyInfo[] propInfos = type.GetProperties();
for (int i = 0; i < propInfos.Length; i++)
{
PropertyInfo pi = (PropertyInfo)propInfos.GetValue(i);
string propName = pi.Name;
}
Try using System.Diagnostics.StackTrace to reflect on the call stack. The property should be somewhere in the call stack (probably at the top if you're calling it directly from the property's code).
My enum consists of the following values:
private enum PublishStatusses{
NotCompleted,
Completed,
Error
};
I want to be able to output these values in a user friendly way though.
I don't need to be able to go from string to value again.
I use the Description attribute from the System.ComponentModel namespace. Simply decorate the enum:
private enum PublishStatusValue
{
[Description("Not Completed")]
NotCompleted,
Completed,
Error
};
Then use this code to retrieve it:
public static string GetDescription<T>(this T enumerationValue)
where T : struct
{
Type type = enumerationValue.GetType();
if (!type.IsEnum)
{
throw new ArgumentException("EnumerationValue must be of Enum type", "enumerationValue");
}
//Tries to find a DescriptionAttribute for a potential friendly name
//for the enum
MemberInfo[] memberInfo = type.GetMember(enumerationValue.ToString());
if (memberInfo != null && memberInfo.Length > 0)
{
object[] attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attrs != null && attrs.Length > 0)
{
//Pull out the description value
return ((DescriptionAttribute)attrs[0]).Description;
}
}
//If we have no description attribute, just return the ToString of the enum
return enumerationValue.ToString();
}
I do this with extension methods:
public enum ErrorLevel
{
None,
Low,
High,
SoylentGreen
}
public static class ErrorLevelExtensions
{
public static string ToFriendlyString(this ErrorLevel me)
{
switch(me)
{
case ErrorLevel.None:
return "Everything is OK";
case ErrorLevel.Low:
return "SNAFU, if you know what I mean.";
case ErrorLevel.High:
return "Reaching TARFU levels";
case ErrorLevel.SoylentGreen:
return "ITS PEOPLE!!!!";
default:
return "Get your damn dirty hands off me you FILTHY APE!";
}
}
}
Maybe I'm missing something, but what's wrong with Enum.GetName?
public string GetName(PublishStatusses value)
{
return Enum.GetName(typeof(PublishStatusses), value)
}
edit: for user-friendly strings, you need to go through a .resource to get internationalisation/localisation done, and it would arguably be better to use a fixed key based on the enum key than a decorator attribute on the same.
I created a reverse extension method to convert the description back into an enum value:
public static T ToEnumValue<T>(this string enumerationDescription) where T : struct
{
var type = typeof(T);
if (!type.IsEnum)
throw new ArgumentException("ToEnumValue<T>(): Must be of enum type", "T");
foreach (object val in System.Enum.GetValues(type))
if (val.GetDescription<T>() == enumerationDescription)
return (T)val;
throw new ArgumentException("ToEnumValue<T>(): Invalid description for enum " + type.Name, "enumerationDescription");
}
The easiest solution here is to use a custom extension method (in .NET 3.5 at least - you can just convert it into a static helper method for earlier framework versions).
public static string ToCustomString(this PublishStatusses value)
{
switch(value)
{
// Return string depending on value.
}
return null;
}
I am assuming here that you want to return something other than the actual name of the enum value (which you can get by simply calling ToString).
That other post is Java. You can't put methods in Enums in C#.
just do something like this:
PublishStatusses status = ...
String s = status.ToString();
If you want to use different display values for your enum values, you could use Attributes and Reflection.
Some other more primitive options that avoid classes/reference types:
Array method
Nested struct method
Array method
private struct PublishStatusses
{
public static string[] Desc = {
"Not Completed",
"Completed",
"Error"
};
public enum Id
{
NotCompleted = 0,
Completed,
Error
};
}
Usage
string desc = PublishStatusses.Desc[(int)PublishStatusses.Id.Completed];
Nested struct method
private struct PublishStatusses
{
public struct NotCompleted
{
public const int Id = 0;
public const string Desc = "Not Completed";
}
public struct Completed
{
public const int Id = 1;
public const string Desc = "Completed";
}
public struct Error
{
public const int Id = 2;
public const string Desc = "Error";
}
}
Usage
int id = PublishStatusses.NotCompleted.Id;
string desc = PublishStatusses.NotCompleted.Desc;
Update (03/09/2018)
A hybrid of Extension Methods and the first technique above.
I prefer enums to be defined where they "belong" (closest to their source of origin and not in some common, global namespace).
namespace ViewModels
{
public class RecordVM
{
//public enum Enum { Minutes, Hours }
public struct Enum
{
public enum Id { Minutes, Hours }
public static string[] Name = { "Minute(s)", "Hour(s)" };
}
}
}
The extension method seems suited for a common area, and the "localized" definition of the enum now makes the extension method more verbose.
namespace Common
{
public static class EnumExtensions
{
public static string Name(this RecordVM.Enum.Id id)
{
return RecordVM.Enum.Name[(int)id];
}
}
}
A usage example of the enum and it's extension method.
namespace Views
{
public class RecordView
{
private RecordDataFieldList<string, string> _fieldUnit;
public RecordView()
{
_fieldUnit.List = new IdValueList<string, string>
{
new ListItem<string>((int)RecordVM.Enum.Id.Minutes, RecordVM.Enum.Id.Minutes.Name()),
new ListItem<string>((int)RecordVM.Enum.Id.Hours, RecordVM.Enum.Id.Hours.Name())
};
}
private void Update()
{
RecordVM.Enum.Id eId = DetermineUnit();
_fieldUnit.Input.Text = _fieldUnit.List.SetSelected((int)eId).Value;
}
}
}
Note: I actually decided to eliminate the Enum wrapper (and Name array), since it's best that the name strings come from a resource (ie config file or DB) instead of being hard-coded, and because I ended up putting the extension method in the ViewModels namespace (just in a different, "CommonVM.cs" file). Plus the whole .Id thing becomes distracting and cumbersome.
namespace ViewModels
{
public class RecordVM
{
public enum Enum { Minutes, Hours }
//public struct Enum
//{
// public enum Id { Minutes, Hours }
// public static string[] Name = { "Minute(s)", "Hour(s)" };
//}
}
}
CommonVM.cs
//namespace Common
namespace ViewModels
{
public static class EnumExtensions
{
public static string Name(this RecordVM.Enum id)
{
//return RecordVM.Enum.Name[(int)id];
switch (id)
{
case RecordVM.Enum.Minutes: return "Minute(s)";
case RecordVM.Enum.Hours: return "Hour(s)";
default: return null;
}
}
}
}
A usage example of the enum and it's extension method.
namespace Views
{
public class RecordView
{
private RecordDataFieldList<string, string> _fieldUnit
public RecordView()
{
_fieldUnit.List = new IdValueList<string, string>
{
new ListItem<string>((int)RecordVM.Enum.Id.Minutes, RecordVM.Enum.Id.Minutes.Name()),
new ListItem<string>((int)RecordVM.Enum.Id.Hours, RecordVM.Enum.Id.Hours.Name())
};
}
private void Update()
{
RecordVM.Enum eId = DetermineUnit();
_fieldUnit.Input.Text = _fieldUnit.List.SetSelected((int)eId).Value;
}
}
}
The simplest way is just to include this extension class into your project, it will work with any enum in the project:
public static class EnumExtensions
{
public static string ToFriendlyString(this Enum code)
{
return Enum.GetName(code.GetType(), code);
}
}
Usage:
enum ExampleEnum
{
Demo = 0,
Test = 1,
Live = 2
}
...
ExampleEnum ee = ExampleEnum.Live;
Console.WriteLine(ee.ToFriendlyString());
You can use Humanizer package with Humanize Enums possiblity. An eaxample:
enum PublishStatusses
{
[Description("Custom description")]
NotCompleted,
AlmostCompleted,
Error
};
then you can use Humanize extension method on enum directly:
var st1 = PublishStatusses.NotCompleted;
var str1 = st1.Humanize(); // will result in Custom description
var st2 = PublishStatusses.AlmostCompleted;
var str2 = st2.Humanize(); // will result in Almost completed (calculated automaticaly)
public enum MyEnum
{
[Description("Option One")]
Option_One
}
public static string ToDescriptionString(this Enum This)
{
Type type = This.GetType();
string name = Enum.GetName(type, This);
MemberInfo member = type.GetMembers()
.Where(w => w.Name == name)
.FirstOrDefault();
DescriptionAttribute attribute = member != null
? member.GetCustomAttributes(true)
.Where(w => w.GetType() == typeof(DescriptionAttribute))
.FirstOrDefault() as DescriptionAttribute
: null;
return attribute != null ? attribute.Description : name;
}
With respect to Ray Booysen, there is a bug in the code: Enum ToString with user friendly strings
You need to account for multiple attributes on the enum values.
public static string GetDescription<T>(this object enumerationValue)
where T : struct
{
Type type = enumerationValue.GetType();
if (!type.IsEnum)
{
throw new ArgumentException("EnumerationValue must be of Enum type", "enumerationValue");
}
//Tries to find a DescriptionAttribute for a potential friendly name
//for the enum
MemberInfo[] memberInfo = type.GetMember(enumerationValue.ToString());
if (memberInfo != null && memberInfo.Length > 0)
{
object[] attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attrs != null && attrs.Length > 0 && attrs.Where(t => t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault() != null)
{
//Pull out the description value
return ((DescriptionAttribute)attrs.Where(t=>t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault()).Description;
}
}
//If we have no description attribute, just return the ToString of the enum
return enumerationValue.ToString();
Instead of using an enum use a static class.
replace
private enum PublishStatuses{
NotCompleted,
Completed,
Error
};
with
private static class PublishStatuses{
public static readonly string NotCompleted = "Not Completed";
public static readonly string Completed = "Completed";
public static readonly string Error = "Error";
};
it will be used like this
PublishStatuses.NotCompleted; // "Not Completed"
Issue using the top "extension method" solutions:
A private enum is often used inside another class. The extension method solution is not valid there since it must be in it's own class. This solution can be private and embedded in another class.
Clean summary of the above suggestions with sample:
namespace EnumExtensions {
using System;
using System.Reflection;
public class TextAttribute : Attribute {
public string Text;
public TextAttribute( string text ) {
Text = text;
}//ctor
}// class TextAttribute
public static class EnumExtender {
public static string ToText( this Enum enumeration ) {
MemberInfo[] memberInfo = enumeration.GetType().GetMember( enumeration.ToString() );
if ( memberInfo != null && memberInfo.Length > 0 ) {
object[] attributes = memberInfo[ 0 ].GetCustomAttributes( typeof(TextAttribute), false );
if ( attributes != null && attributes.Length > 0 ) {
return ( (TextAttribute)attributes[ 0 ] ).Text;
}
}//if
return enumeration.ToString();
}//ToText
}//class EnumExtender
}//namespace
USAGE:
using System;
using EnumExtensions;
class Program {
public enum Appearance {
[Text( "left-handed" ) ]
Left,
[Text( "right-handed" ) ]
Right,
}//enum
static void Main( string[] args ) {
var appearance = Appearance.Left;
Console.WriteLine( appearance.ToText() );
}//Main
}//class
Use Enum.GetName
From the above link...
using System;
public class GetNameTest {
enum Colors { Red, Green, Blue, Yellow };
enum Styles { Plaid, Striped, Tartan, Corduroy };
public static void Main() {
Console.WriteLine("The 4th value of the Colors Enum is {0}", Enum.GetName(typeof(Colors), 3));
Console.WriteLine("The 4th value of the Styles Enum is {0}", Enum.GetName(typeof(Styles), 3));
}
}
// The example displays the following output:
// The 4th value of the Colors Enum is Yellow
// The 4th value of the Styles Enum is Corduroy
According to this documentation: https://learn.microsoft.com/pt-br/dotnet/api/system.enum.tostring?view=netframework-4.8
It is possible to just convert a enumerator to string using a format like this:
public enum Example
{
Example1,
Example2
}
Console.WriteLine(Example.Example1.ToString("g"));
//Outputs: "Example1"
You can see all the possible formats in this link: https://learn.microsoft.com/pt-br/dotnet/api/system.string?view=netframework-4.8
I happen to be a VB.NET fan, so here's my version, combining the DescriptionAttribute method with an extension method. First, the results:
Imports System.ComponentModel ' For <Description>
Module Module1
''' <summary>
''' An Enum type with three values and descriptions
''' </summary>
Public Enum EnumType
<Description("One")>
V1 = 1
' This one has no description
V2 = 2
<Description("Three")>
V3 = 3
End Enum
Sub Main()
' Description method is an extension in EnumExtensions
For Each v As EnumType In [Enum].GetValues(GetType(EnumType))
Console.WriteLine("Enum {0} has value {1} and description {2}",
v,
CInt(v),
v.Description
)
Next
' Output:
' Enum V1 has value 1 and description One
' Enum V2 has value 2 and description V2
' Enum V3 has value 3 and description Three
End Sub
End Module
Basic stuff: an enum called EnumType with three values V1, V2 and V3. The "magic" happens in the Console.WriteLine call in Sub Main(), where the last argument is simply v.Description. This returns "One" for V1, "V2" for V2, and "Three" for V3. This Description-method is in fact an extension method, defined in another module called EnumExtensions:
Option Strict On
Option Explicit On
Option Infer Off
Imports System.Runtime.CompilerServices
Imports System.Reflection
Imports System.ComponentModel
Module EnumExtensions
Private _Descriptions As New Dictionary(Of String, String)
''' <summary>
''' This extension method adds a Description method
''' to all enum members. The result of the method is the
''' value of the Description attribute if present, else
''' the normal ToString() representation of the enum value.
''' </summary>
<Extension>
Public Function Description(e As [Enum]) As String
' Get the type of the enum
Dim enumType As Type = e.GetType()
' Get the name of the enum value
Dim name As String = e.ToString()
' Construct a full name for this enum value
Dim fullName As String = enumType.FullName + "." + name
' See if we have looked it up earlier
Dim enumDescription As String = Nothing
If _Descriptions.TryGetValue(fullName, enumDescription) Then
' Yes we have - return previous value
Return enumDescription
End If
' Find the value of the Description attribute on this enum value
Dim members As MemberInfo() = enumType.GetMember(name)
If members IsNot Nothing AndAlso members.Length > 0 Then
Dim descriptions() As Object = members(0).GetCustomAttributes(GetType(DescriptionAttribute), False)
If descriptions IsNot Nothing AndAlso descriptions.Length > 0 Then
' Set name to description found
name = DirectCast(descriptions(0), DescriptionAttribute).Description
End If
End If
' Save the name in the dictionary:
_Descriptions.Add(fullName, name)
' Return the name
Return name
End Function
End Module
Because looking up description attributes using Reflection is slow, the lookups are also cached in a private Dictionary, that is populated on demand.
(Sorry for the VB.NET solution - it should be relatively straighforward to translate it to C#, and my C# is rusty on new subjects like extensions)
Even cleaner summary:
using System;
using System.Reflection;
public class TextAttribute : Attribute
{
public string Text;
public TextAttribute(string text)
{
Text = text;
}
}
public static class EnumExtender
{
public static string ToText(this Enum enumeration)
{
var memberInfo = enumeration.GetType().GetMember(enumeration.ToString());
if (memberInfo.Length <= 0) return enumeration.ToString();
var attributes = memberInfo[0].GetCustomAttributes(typeof(TextAttribute), false);
return attributes.Length > 0 ? ((TextAttribute)attributes[0]).Text : enumeration.ToString();
}
}
Same usage as underscore describes.
In case you just want to add a whitespace between the words, it is as simple as
string res = Regex.Replace(PublishStatusses.NotCompleted, "[A-Z]", " $0").Trim();
This is an update to Ray Booysen's code that uses the generic GetCustomAttributes method and LINQ to make things a bit tidier.
/// <summary>
/// Gets the value of the <see cref="T:System.ComponentModel.DescriptionAttribute"/> on an struct, including enums.
/// </summary>
/// <typeparam name="T">The type of the struct.</typeparam>
/// <param name="enumerationValue">A value of type <see cref="T:System.Enum"/></param>
/// <returns>If the struct has a Description attribute, this method returns the description. Otherwise it just calls ToString() on the struct.</returns>
/// <remarks>Based on http://stackoverflow.com/questions/479410/enum-tostring/479417#479417, but useful for any struct.</remarks>
public static string GetDescription<T>(this T enumerationValue) where T : struct
{
return enumerationValue.GetType().GetMember(enumerationValue.ToString())
.SelectMany(mi => mi.GetCustomAttributes<DescriptionAttribute>(false),
(mi, ca) => ca.Description)
.FirstOrDefault() ?? enumerationValue.ToString();
}
I'm 7 years late for the party :-) But I'm sure this topic is visited frequently. So I wanted to add a little sugar to the coffee:
What about the "F" format string specifier?
PublishStatusses[] ps = Enum.GetValues<PublishStatusses>();
ps.ToList().ForEach(c => Console.Write($"{c:F} "));
There is no need for any explicit function call.
In fact there isn't even need for any format specifier.
In case of a variable assignment to a string, ToString() does the work:
string foo = PublishStatusses.Error.ToString(); // or ToString("F")
And if it is about to insert spaces between words of a CamelCase string, you can just use a regular expression:
Regex.Replace(foo, "(\\B[A-Z])", " $1")
For flags enum including.
public static string Description(this Enum value)
{
Type type = value.GetType();
List<string> res = new List<string>();
var arrValue = value.ToString().Split(',').Select(v=>v.Trim());
foreach (string strValue in arrValue)
{
MemberInfo[] memberInfo = type.GetMember(strValue);
if (memberInfo != null && memberInfo.Length > 0)
{
object[] attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attrs != null && attrs.Length > 0 && attrs.Where(t => t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault() != null)
{
res.Add(((DescriptionAttribute)attrs.Where(t => t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault()).Description);
}
else
res.Add(strValue);
}
else
res.Add(strValue);
}
return res.Aggregate((s,v)=>s+", "+v);
}
Just use a static class that simulate an enum:
public static class PublishStatusses{
public const string NotCompleted = "Not Completed";
public const string Completed = "Completed";
public const string Error = "Error"
};
And to access the values, just use like an enum:
PublishStatusses.NotCompleted;
I use a generic class to store the enum/description pairs and a nested helper class to get the description.
The enum:
enum Status { Success, Fail, Pending }
The generic class:
Note: Since a generic class cannot be constrained by an enum I am constraining by struct instead and checking for enum in the constructor.
public class EnumX<T> where T : struct
{
public T Code { get; set; }
public string Description { get; set; }
public EnumX(T code, string desc)
{
if (!typeof(T).IsEnum) throw new NotImplementedException();
Code = code;
Description = desc;
}
public class Helper
{
private List<EnumX<T>> codes;
public Helper(List<EnumX<T>> codes)
{
this.codes = codes;
}
public string GetDescription(T code)
{
EnumX<T> e = codes.Where(c => c.Code.Equals(code)).FirstOrDefault();
return e is null ? "Undefined" : e.Description;
}
}
}
Usage:
EnumX<Status>.Helper StatusCodes = new EnumX<Status>.Helper(new List<EnumX<Status>>()
{
new EnumX<Status>(Status.Success,"Operation was successful"),
new EnumX<Status>(Status.Fail,"Operation failed"),
new EnumX<Status>(Status.Pending,"Operation not complete. Please wait...")
});
Console.WriteLine(StatusCodes.GetDescription(Status.Pending));
I think the best (and easiest) way to solve your problem is to write an Extension-Method for your enum:
public static string GetUserFriendlyString(this PublishStatusses status)
{
}
If you want something completely customizable, try out my solution here:
http://www.kevinwilliampang.com/post/Mapping-Enums-To-Strings-and-Strings-to-Enums-in-NET.aspx
Basically, the post outlines how to attach Description attributes to each of your enums and provides a generic way to map from enum to description.