How many times do you need to summarize values on one of your objects with a rol up summary? And on salesforce you can create a roll-up summary field to display a value in a master record based on the values of fields in a detail record. BUT .. the detail record must be related to the master through a master-detail relationship.
Not any longer. There are a couple of paid tools on the Appexchange that give you the ability to build roll up summaries through cross object relationships but free and unlimited is always better!
Let me introduce you to Andrew Fawcett’s amazing Declarative Roll Up Summary Tool which will be the answer to your roll up prayers.
To quote Andrew …
Salesforce is great for making object creation and data collection super easy. One thing it doesn’t make so easy is jumping tables as you MUST use a Master Lookup if you want to use Rollup Summary fields and those are even limited in the functions they can do. You just want to move a field off of a child record onto the parent, or maybe just grab the user name of the last completed activity and write it to the opportunity record that task was related to. Before it would take some fancy apex or other developer style work to accomplish.
This blog is going to be a super broken down step by step of how to DLRS, the most common issues you might run into with it and a few ways I use it. Pro-Tip don’t try and install this from the app exchange you will find a very out-dated version that no longer installs. So, to install the package head over to the github (https://github.com/afawcett/declarative-lookup-rollup-summaries) and click either Sandbox or Production for the latest version. I’d recommend giving it a spin in your sandbox first.
His tool is simple to install through the link provided. It includes test classes so if you need to make use of it in managed apps and the like it wont cause you any problems and it just works.. every time.