created: 20140711090154150
modified: 20160606122804180
tags: Mechanisms
title: UpgradeMechanism

# Open upgrade.html
# Includes a data tiddler called `$:/UpgradeLibrary` that contains the latest compatible versions of all plugins in the library
# Drag in old wiki file
# Place tiddlers into a data tiddler `$:/Import` that is typed as a "pending import"
# Kick off import processing for each tiddler
## Give each "upgrader" module a chance to inspect the incoming tiddlers
## Upgrader modules can trigger actions for each tiddler:
##* Display a warning message
##* Don't import
##* Replace with another tiddler from the upgrade library
##* Disable incompatible plugins
# Display the newly created pending import tiddler through a new view template segment
## Displays the payload tiddlers as a list of titles and checkboxes, with a dropdown showing the full details of the tiddler
## Perhaps we also suppress the usual JSON display for data tiddlers behind a reveal widget
# The user can adjust the selection checkboxes
# Clicking "Upgrade" unpacks the selected tiddlers from the pending import tiddler
# The pending import tiddler and the upgrade library tiddler are excluded from the subsequent save operation