Apps are bundled in packages. When a new version of a package is released,
users are going to update the package, and with it all apps in the package.
It may be necessary to apply changes to all instances of those apps,
for example, when an attribute named foo is to be renamed to bar.
The .Update method is for this purpose: to update all affected files.
(All files that are instances of apps of the updated package.)
Let’s assume you are the vendor of the package example.com, and you have a
gallery app at example.com/gallery-1. Your app uses a string attribute foo
that you want to rename to bar.
/gallery-2 to hold the new version of the app.app-1./gallery-1/.Update..Update file’s link property to path /gallery-2.
(This documents that the /gallery-2 app supersedes the /gallery-1 app.
Required to do updates one version at a time.).Update file’s type to sjs-4 or any interpreter of your choice,
and write the code that will do the transformation:
f will point to the instance being transformed (migrated).f may have a longer typeChain to your app.
It is guaranteed that the files on the typeChain of f will be updated
after f itself. Thus, the typeChain of f ends in /gallery-1.foo to bar.
(Create a new attribute, remove the old one.)f to point to /gallery-2, it will
be done automatically.
In fact, it may not need to be updated, if there is a longer typeChain. (!)/gallery-1/* to /gallery-2/*.sjs-4
os.updateInstances()
method.Updating an entire package runs in a single transaction.
In the above example, never ever remove the file /gallery-1. It makes sure
that restoring an old version of a website will continue to just work.
.ContentSecurityPolicy rules of a website during an update is not currently
supported. Get in touch if you need it implemented.
Note that the website owner will have to approve .ContentSecurityPolicy changes every single
time.