As with most other software it’s safer to try new plugins, configuration options or template changes in a separate testing environment, see e.g. WordPress local development environment.
Most questions and answers I’ve seen about this is the simpler case: doing the initial development locally and then deploy everything to the live site. That is easy. However, what if I need to test some change in the middle of site’s life cycle? I guess the steps should be:
- Replicate a current state of the site to the testing environment
- Test the changes in the testing environment
- When done, merge the changes back to live
I know how to do 1+2 but am not sure about 3. This steps breaks down to 2 parts:
- Files
- Database
Again, 1 is easy so for example template updates are easily migrated from test to live. But 2 is tricky. Copying test db to live is not always possible (there might have been content changes in the meantime etc.), comparing schemas is also not a trivial task, theoretically there could be a plugin that would help with test <-> live synchronization but I’m not sure if it exists.
How do you people deal with this? Any tips & tricks or procedures?
I don’t think you will find any comprehensive or easy answer for this. I think the way you already broke down the various aspects of your installation is the key – i.e., thinking of changes to files as different from changes to the database.
Most of the changes I make are at the file level – e.g., CSS, adding code for a hook, stuff like that. They are isolated in files, as you said.
For the changes I make which affect the database, they tend to be compartmentalized as plugins, so they are also easy to isolate and deploy or rollback as long as I keep track of what steps I am taking.
Since you seem more concerned about your database changes, do you have a particular change or type of change that you want to discuss? You could consider doing a MySql dump of both the test and live database and then using a file diff tool to find the differences. In many cases this would probably let you extract a few SQL commands that could be packaged into a deployment script (but this could involve a fair amount of understanding about the underlying database to be sure to get the script right).
It might sound counterproductive, but to transfer changes locally I usually just delete the database on my local environment, dump a copy of the live database and then open it up in a text editor and do a find and replace of the live url to be that of my local url.
So for example if my live site is: http://www.awesomewidgets.com and my local test url is: http://localhost/awesomewidgets – I’d do a search and replace of “http://www.awesomewidgets.com” and make it “http://localhost/awesomewidgets”
You just then have to remember to copy over any plugins you might have installed on the live site and of course, any uploaded files like images, videos or audio files which are usually inside of your wp-content/uploads folder (unless you changed it).