How to create an XmlMappingSource during runtime?

Question

(Follow-Up-Question to How to change LINQ O/R-M table name/source during runtime?)

I need to change the table source of a LINQ 2 SQL O/R-Mapper table during runtime. To achieve this, I need to create an XmlMappingSource. On command line, I could use SqlMetal to create this mapping file, but I would like to create the mapping file during runtime in memory. The XmlMappingSource is a simple xml file, looking something like this:

<?xml version="1.0" encoding="utf-8"?>
<Database Name="MyDatabase" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007"&gt;
  <Table Name="dbo.MyFirstTable" Member="MyFirstTable">
    <Type Name="MyFirstTable">
      <Column Name="ID" Member="ID" Storage="_ID" DbType="UniqueIdentifier NOT NULL" IsPrimaryKey="true" IsDbGenerated="true" AutoSync="OnInsert" />
      <Association Name="WaStaArtArtikel_WaVerPreisanfragen" Member="WaStaArtArtikel" Storage="_WaStaArtArtikel" ThisKey="ArtikelID" OtherKey="ID" IsForeignKey="true" />
    </Type>
  </Table>
  <Table Name="dbo.MySecondTable" Member="MySecondTable">
    <Type Name="MySecondTable">
      <Column Name="ID" Member="ID" Storage="_ID" DbType="UniqueIdentifier NOT NULL" IsPrimaryKey="true" IsDbGenerated="true" AutoSync="OnInsert" />
      <Column Name="FirstTableID" Member="FirstTableID" Storage="_FirstTableID" DbType="UniqueIdentifier NOT NULL" />
      <Association Name="MySecondTable_MyFirstTable" Member="MyFirstTable" Storage="_MyFirstTable" ThisKey="FirstTableID" OtherKey="ID" IsForeignKey="true" />
    </Type>
  </Table>
</Database>

This should be possible to create using reflection, for example I can get the database name from a data context like this:

using System.Data.Linq.Mapping;
using System.Xml.Linq;

XDocument mapWriter = new XDocument();
DatabaseAttribute[] catx = (DatabaseAttribute[])typeof(WcfInterface.WaDataClassesDataContext).GetCustomAttributes(typeof(DatabaseAttribute), false);
XElement xDatabase = new XElement("Database");
xDatabase.Add(new XAttribute("Name", catx[0].Name));
mapWriter.Add(xDatabase);

My problem: I can't find good documentation of the mapping, so extracting the necessary information is quite error-prone - maybe someone can point me to good docs of the mapping, or, even better, to a code example how to create the mapping file?

Answer 1

Have you considered using LINQ to Entities, the mapping formats for LINQ to Entities are documented.

Answer 2

Use Damien Guard's Open Source T4 templates. They do everything SQLMetal can do and more, and you'll have the full T4 engine behind you.