Many customers have asked us how to port a LINQ to SQL application to the Entity Framework. In order to make this process easier, we have developed a metadata conversion template.
This template converts LINQ to SQL metadata (.dbml) to metadata compatible with Entity Framework (.edmx). While not a complete solution to the conversion problem, it is a useful first step. The template available for download is still in the development stage, and any feedback you have on the user experience, additional features, or any other aspect of the conversion would be greatly appreciated.
The T4 template is intended to convert simple valid .dbml files to .edmx files. All of the basic elements of the .dbml file are mapped to their .edmx counterparts. For instance, Tables are mapped to EntitySets and Types are mapped to EntityTypes. Additionally, stored procedures (including customized insert, update and delete stored procedures) and associations are also converted.
Downloading the Metadata Conversion Template
Included in the zip file is a .vsix installer for the T4 Conversion Template. Also included is detailed documentation for the template. VS 2010 Beta 1 is required.
Two walkthroughs have been written to help guide users through the conversion process. The walkthroughs both take the form of unit tests which can be run against the existing LINQ to SQL metadata and the Entity Framework metadata produced by the conversion template. Each walkthrough contains detailed instructions on how to convert the existing LINQ to SQL project to Entity Framework using the Conversion Template. The first is the Widget Factory walkthrough, which shows a basic conversion. The second (CustomCUD) shows how to convert a LINQ to SQL project which uses custom insert, update and delete stored procedures. The walkthroughs are available individually.
Caveats and Known Issues
Because the Conversion Template is still under development, there are a number of open issues and unimplemented features. A more comprehensive list can be found in the documentation included with the template installer.
· Inheritance: Inheritance has not been fully implemented. While the template may work in some basic cases, this aspect of the conversion remains an open issue.
· Independent Associations: Foreign-key associations will not be available until .NET 4.0 Beta 2, so the current version of the template will only work with the "UseIndependentAssociations" flag set to true.
· Property Attributes: not all of the property attributes (such as "Unicode" and "FixedLength") are converted because these are not explicitly present in the .dbml file.
We are interested to hear any comments you have about known issues, additional feature requests, suggestions for additional walkthroughs or any other aspect of the conversion process.
Entity Framework Team