Automatically create an Enum based on values in a

Question

How do I automatically create an enum and subsequently use its values in C# based on values in a database lookup table (using enterprise library data layer)?

For example, If I add a new lookup value in the database, I don't want to have to manually add the extra static enum value declaration in code - I'd like to keep the enum in sync with the database.

Is there such a thing as this?

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I don't want to create a code generated static enum (as per The Code Project article Enum Code Generator - Generating enum code automatically from database look up tables) and would prefer it to be completely automatic.

Answer 1

Does it have to be an actual enum? How about using a Dictionary<string,int> instead?

for example

Dictionary<string, int> MyEnum = new Dictionary(){{"One", 1}, {"Two", 2}};
Console.WriteLine(MyEnum["One"]);

Answer 2

You could use CodeSmith to generate something like this:

http://www.csharping.com/PermaLink,guid,cef1b637-7d37-4691-8e49-138cbf1d51e9.aspx

Answer 3

One way to keep the Enums and to create a Dynamic list of values at the same time is to use the Enums that you currently have with a Dynamically created Dictionary.

Since most Enums are used in the context that they are defined to be used, and the "dynamic enums" will be supported by dynamic processes, you can distinguish the 2.

The first step is to create a table/collection that houses the IDs and References for the Dynamic Entries. In the table you will autoincrement much larger than your largest Enum value.

Now comes the part for your dynamic Enums, I am assuming that you will be using the Enums to create a set of conditions that apply a set of rules, some are dynamically generated.

Get integer from database
If Integer is in Enum -> create Enum -> then run Enum parts
If Integer is not a Enum -> create Dictionary from Table -> then run Dictionary parts.

Answer 4

Aren't we coming to this from the wrong direction?

If the data is likely to change at all during the lifetime of the deployed release then an enum is just not appropriate, and you need to use a dictionary, hash or other dynamic collection.

If you know the set of possible values is fixed for the life of the deployed release, then an enum is preferable.

If you must have something in your database that replicates the enumerated set, then why not add a deployment step to clear and repopulate the database table with the definitive set of enum values?

Answer 5

I don't think there is a good way of doing what you want. And if you think about it I don't think this is what you really want.

If you would have a dynamic enum, it also means you have to feed it with a dynamic value when you reference it. Maybe with a lot of magic you could achieve some sort of IntelliSense that would take care of this and generate an enum for you in a DLL file. But consider the amount of work it would take, how uneffective it would be to access the database to fetch IntelliSense information as well as the nightmare of version controlling the generated DLL file.

If you really don't want to manually add the enum values (you'll have to add them to the database anyway) use a code generation tool instead, for example T4 templates. Right click+run and you got your enum statically defined in code and you get all the benefits of using enums.

Answer 6

enum builder class

public class XEnum
{
    private EnumBuilder enumBuilder;
    private int index;
    private AssemblyBuilder _ab;
    private AssemblyName _name;
    public XEnum(string enumname)
    {
        AppDomain currentDomain = AppDomain.CurrentDomain;
        _name = new AssemblyName("MyAssembly");
        _ab = currentDomain.DefineDynamicAssembly(
            _name, AssemblyBuilderAccess.RunAndSave);

        ModuleBuilder mb = _ab.DefineDynamicModule("MyModule");

        enumBuilder = mb.DefineEnum(enumname, TypeAttributes.Public, typeof(int));


    }
    /// <summary>
    /// adding one string to enum
    /// </summary>
    /// <param name="s"></param>
    /// <returns></returns>
    public FieldBuilder add(string s)
    {
        FieldBuilder f = enumBuilder.DefineLiteral(s, index);
        index++;
        return f;
    }
    /// <summary>
    /// adding array to enum
    /// </summary>
    /// <param name="s"></param>
    public void addRange(string[] s)
    {
        for (int i = 0; i < s.Length; i++)
        {
            enumBuilder.DefineLiteral(s[i], i);
        }
    }
    /// <summary>
    /// getting index 0
    /// </summary>
    /// <returns></returns>
    public object getEnum()
    {
        Type finished = enumBuilder.CreateType();
        _ab.Save(_name.Name + ".dll");
        Object o1 = Enum.Parse(finished, "0");
        return o1;
    }
    /// <summary>
    /// getting with index
    /// </summary>
    /// <param name="i"></param>
    /// <returns></returns>
    public object getEnum(int i)
    {
        Type finished = enumBuilder.CreateType();
        _ab.Save(_name.Name + ".dll");
        Object o1 = Enum.Parse(finished, i.ToString());
        return o1;
    }
}

create an object

string[] types = { "String", "Boolean", "Int32", "Enum", "Point", "Thickness", "long", "float" };
XEnum xe = new XEnum("Enum");
        xe.addRange(types);
        return xe.getEnum();