How do I add a confirmation form after the user clicks on "Save" in an edit form? On a site I'm building, a user can edit certain fields on a node that cause a chain reaction to happen (which I've implemented using hook_nodeapi() and its &quot;update&quot; operation).
Since this chain reaction potentially affects a lot of other content, I'd like to inform the user of exactly what other content will be changed, which depends on the changed field values, unknow until the user submits the node.  After the user has read the list of affected content, I'd like to give them the option to click on Yes, which will save the node and start the chain reaction, or click No, which will take them back to the node edit form (with edits intact).
How can I make a confirmation form appear after the user clicks on Save?
In brief, this is what I think you need to do in a custom module:


After validation, override the submit function on the node form to submit to a new interstitial page (you'll need to implement hook_menu to create the new page)
Pass the node object to the new interstitial page and define whatever logic you need in the interstitial page's callback function.
Create a new form on the interstitial page that runs node_save on submit with node object that was passed to it.