How Can Enums Be Dynamically Generated from a Database Lookup Table?

Dynamically generate enumerations from database lookup table

How to automatically generate enumerations based on values ​​stored in a database lookup table and keep the enumerations in sync with the database without manually modifying the code? This is a common question.

Code generation solutions

While it cannot be fully automated, code generation can provide a solution. Automatic generation of enumerations can be achieved by creating a separate project called "EnumeratedTypes" in the solution. This project acts as a console application, retrieving values ​​from the database, constructing enumerations from those values, and saving them into a separate assembly.

In this code generation project, use the following code to define and populate dynamic enumerations:

<code class="language-csharp">// 创建动态程序集
AssemblyName name = new AssemblyName("MyEnums");
AssemblyBuilder assemblyBuilder = currentDomain.DefineDynamicAssembly(name, AssemblyBuilderAccess.RunAndSave);

// 定义动态模块
ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(name.Name, name.Name + ".dll");

// 定义公共枚举
EnumBuilder myEnum = moduleBuilder.DefineEnum("EnumeratedTypes.MyEnum", TypeAttributes.Public, typeof(int));

// 从数据库检索数据
MyDataAdapter someAdapter = new MyDataAdapter();
MyDataSet.MyDataTable myData = myDataAdapter.GetMyData();

// 定义枚举文字
foreach (MyDataSet.MyDataRow row in myData.Rows)
{
    myEnum.DefineLiteral(row.Name, row.Key);
}

// 创建枚举并保存程序集
myEnum.CreateType();
assemblyBuilder.Save(name.Name + ".dll");</code>

Other projects in the solution can reference this generated assembly, thereby accessing dynamic enumerations and providing IntelliSense support.

Post-build event automation

To ensure automatic generation of enumerations, the "EnumeratedTypes" project can add a post-build event. This event will run during the build process and generate the "MyEnums.dll" file.

Other notes

• Modify the build order to ensure that the "EnumeratedTypes" project is built first to prevent build failure if "MyEnums.dll" is deleted.
• Refer to the MSDN article for further details on dynamic code generation.

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