Question

can I force the DBML designer to use my custom types instead of the Auto-generated Types?
I can edit the database.designer.cs, but these changes will be lost when I modify the tables.

If not, how can I easily “convert” from the auto-generated type to my custom type in Linq?

Answer 1

The DBML designer is code-gen, plain and simple – although the dml may help as the mapping file

There are various options here:

• use SqlMetal to generate the mapping file
• decorate your existing objects with the standard attributes
• use an external xml file to describe the relationships

Resources:

• External Mapping Reference (LINQ to SQL)
• LINQ In Action describes both options.
• Using LINQ to SQL XML Mapping Files – Step by Step

Note also that EF in 4.0 also supports POCO.

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If you just want to manually project from the LINQ type to your type; if they have similar properties, something like PropertyCopy in MiscUtil may help – see this answer.