Updated: Oct 8, 2020
Hey #AwesomeAdmins, from winter 21 we have the power to launch trigger flows on delete event. So, here I am using that to complete the rollup using flows ( No Need of Triggers ).
So we have to create two flows, first one will trigger on Create and update. The second one will trigger whenever any related record gets deleted. Here I have created a currency field on the account and I want the rollup of the related opportunity's amount field to be displayed on this new field.
Here is my first flow (with new auto-builder feature)-
Here we are using A record is created or updated which runs on After the record is saved.
Second Flow -
This runs whenever a record is deleted, this flow also checks if the last related record is deleted then it puts 0 in the rollup field.
So that's it! Make sure you activate your flows and then just see the power of these awesome flows. If you want to try this, you can do hands-on here on the trial org - https://www.salesforce.com/form/signup/prerelease-winter21/
Also, I have created a package for these flows. If you want to use them just change the object and the field that you want to rollup. Here is the link - https://login.salesforce.com/packaging/installPackage.apexp?p0=04tB0000000UNie
Do let me know, your experiences! Thanks for your time.