Check That Your Config Files Are Transformed Correctly
Having a process to manage the settings in your application's Web.config file as you move from release to production is essential to ensuring your production Web site works correctly.
One way to handle that is to set up a Web.release.config file with transformation rules to convert your development config file to your production version whenever you compile in Release mode.
In Visual Studio, you can check to see if that transformation is doing what you want by right-clicking on the Web.release.config file in Solution Explorer and then selecting Preview Transformation from the popup menu. Selecting Preview Transformation will open a window with two panes; the pane on the left shows your original file, while the pane on the right shows your transformed version.
Any lines that are modified, added or deleted are automatically highlighted in both panes, making it easy to see what changes will be made. You don't even have to go looking for the changes, either: There's a bar down the right side of the window, flagging where in your config file you'll find your changed lines.
Do be careful, though: It's possible to write your transformation so it doesn't find the part of your config file it's supposed to transform and, as a result, no transformation is made. Other than the absence of a change (something that's hard to notice), there's nothing in the preview to flag that your transformation has failed.
Posted by Peter Vogel on 01/05/2018 at 10:04 AM