I’m a fan of the new VS 2010 Web.config transformations. I use this feature for deployment purposes and wondered if it is possible to use them for debugging too.
I think of using them in the IDE: I want to create different built configuration (with linked transformation configurations); choose one of them; start the web site in the IDE and debug the different configurations this way.
Update
Thanks to a 3rd party plugin, SlowCheetah, this is now possible. Scot Hanselman has a blog post about it.
Original response:
Unfortunately, the web.config transformations appear to effect only publishing sites and building deployment packages.
In our scenario we have two development groups, one with access to multiple environments (in-house) and the other with access to a single environment (offshore). We have periods where the in-house group needs to debug directly against QA, while offshore remains locked-out (so their web.config's must point to the dev environment).
We were hoping to have 1x build-configuration per-environment, and be able to choose the build-configuration which matched the environment to debug against--which, as I understand it is your question.
In case anyone is curious why they haven't built this feature, from: http://forums.asp.net/p/1532038/3711423.aspx
"When the web app gets run, the web.config under project root folder will be picked up by asp.net and I know unfortunately it is under source control . I certainly understand the cleanness coming with letting runtime use a transformed web.config from a temp folder; however, asp.net runtime doesn't know anything about vs projec structure and it is totaly based on directory structure. Using alternate path might also break as a web.config under a subfolder expect to inherit settings from the upper level of directory."
I found an alternative solution that does not involve any third party tool: http://ledtalks.blogspot.in/2011/09/webconfig-transformations-when.html. I only tried this for the web.config file
来源：https://stackoverflow.com/questions/2990384/vs-2010-web-config-transformations-for-debugging