T4 template to Generate Enums

Question

I'm looking at creating a T4 template to generate enums of my database. Essentially, I want the same feature as SubSonic e.g. Product.Columns.ProductId for Linq-to-SQL or Entity Framework 4.

Any help would be much appreciated. thanks.

Answer 1

I have written one for my needs that converts a lookup table of your choice to an enum: Put this code inside an EnumGenerator.ttinclude file:

<#@ template debug="true" hostSpecific="true" #>
<#@ output extension=".generated.cs" #>
<#@ Assembly Name="System.Data" #>
<#@ import namespace="System.Data" #>
<#@ import namespace="System.Data.SqlClient" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="System.Text.RegularExpressions" #>
<#
    string tableName = Path.GetFileNameWithoutExtension(Host.TemplateFile);
    string path = Path.GetDirectoryName(Host.TemplateFile);
    string columnId = tableName + "ID";
    string columnName = "Name";
    string connectionString = "data source=.;initial catalog=DBName;integrated security=SSPI";
#>
using System;
using System.CodeDom.Compiler;

namespace Services.<#= GetSubNamespace() #>
{
    /// <summary>
    /// <#= tableName #> auto generated enumeration
    /// </summary>
    [GeneratedCode("TextTemplatingFileGenerator", "10")]
    public enum <#= tableName #>
    {
<#
    SqlConnection conn = new SqlConnection(connectionString);
    string command = string.Format("select {0}, {1} from {2} order by {0}", columnId, columnName, tableName);
    SqlCommand comm = new SqlCommand(command, conn);

    conn.Open();

    SqlDataReader reader = comm.ExecuteReader();
    bool loop = reader.Read();

    while(loop)
    {
#>      /// <summary>
        /// <#= reader[columnName] #> configuration setting.
        /// </summary>
        <#= Pascalize(reader[columnName]) #> = <#= reader[columnId] #><# loop = reader.Read(); #><#= loop ? ",\r\n" : string.Empty #>
<#
    }
#>  }
}
<#+
    private string Pascalize(object value)
    {
        Regex rx = new Regex(@"(?:[^a-zA-Z0-9]*)(?<first>[a-zA-Z0-9])(?<reminder>[a-zA-Z0-9]*)(?:[^a-zA-Z0-9]*)");
        return rx.Replace(value.ToString(), m => m.Groups["first"].ToString().ToUpper() + m.Groups["reminder"].ToString().ToLower());
    }

    private string GetSubNamespace()
    {
        Regex rx = new Regex(@"(?:.+Services\s)");
        string path = Path.GetDirectoryName(Host.TemplateFile);
        return rx.Replace(path, string.Empty).Replace("\\", ".");
    }
#>

Then whenever you'd like an enum to be generated, just create a tt file with the same name as database table like UserType.tt and put this code in:

<#@ include file="..\..\T4 Templates\EnumGenerator.ttinclude" #>

An even more advanced template is now available in my blog post.

Answer 2

Alternative implementation of Pascalize:

private static string Pascalize(object value)
{
    if (value == null)
        return null;

    string result = value.ToString();

    if (string.IsNullOrWhiteSpace(result))
        return null;

    result = new String(result.Select(ch => ((ch >= '0' && ch <= '9' || ch >= 'a' && ch <= 'z') ? ch : ((ch >= 'A' && ch <= 'Z') ? ((char)((int)ch + (int)'a' - (int)'A')) : '-'))).ToArray());
    string[] words = result.Split(new [] {'-'}, StringSplitOptions.RemoveEmptyEntries);
    words = words.Select(w => ((w[0] >= 'a' && w[0] <= 'z') ? (w.Substring(0, 1).ToUpper() + w.Substring(1)) : w)).ToArray();
    result = words.Aggregate((st1, st2) => st1 + st2);
    if (result[0] >= '0' && result[0] <= '9')
        result = '_' + result;

    return result;
}

If you end up with a null result, I recommend using "Value" + id as value.

Result must be compared to previous values, you can add '_' to end if you have duplicates created (due to bad data or omitted characters).

E.g.

int value = Convert.ToInt32(reader[enumTable.ValueId]);
string name = Pascalize(reader[enumTable.ValueName].ToString());
if (string.IsNullOrWhiteSpace(name))
    name = "Value" + value;

while (result.Values.Where(v => v.Name == name).SingleOrDefault() != null)
    name += '_';