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?
The DBML designer is code-gen, plain and simple - although the dml may help as the mapping file
There are various options here:
Resources:
Note also that EF in 4.0 also supports POCO.
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.