In Salesforce, relationship fields – such as Lookup, Master-Detail, or Hierarchical – allow a customer to connect one object with another object. Now imagine a use case where a customer wants to connect one object with multiple objects – i.e., relate a child object to multiple parents objects. In this blog, I will guide you through the process of, understanding and using, polymorphic relationship to relate a child object record with multiple parent objects. We will discuss, how we can use Process Builder to update parent object in case of the polymorphic relationship. 

So let us get started. Suppose you want to connect an object with multiple parents objects –  Student (child), College (parent) and Account (parent). Via a Lookup, or a Master-Detail, relationship, you can either connect a Student (child) record to a College (parent) record; or a Student (child) record to an Account (parent) record. Now imagine a use case where you want to relate the Student (child) record to multiple parent records simultaneously – for example, a Student (child) record to a College (parent) record and an Account (parent) record.

If this is the case, then, you need to use the polymorphic key, to relate a child record, to multiple parents record.

Another example of the polymorphic relationship is Whoid and Whatid fields on the Event object. The WhatId field of an Event could be an Account, a Campaign, or an Order.

To summarize, when a field has a relationship with more than one object, it is called a polymorphic relationship. Using a Polymorphic Key, you can relate a single (child) field to multiple parent records – be it Account, Contact, Order, Quote, etc. For example, if you have Queues enabled for Leads, a Lead Owner can be either a User or Queue.

A glance at the following image shows how a polymorphic key – refer to right image below, ‘With Polymorphic Key’ – significantly streamlines an object mapping process.

As of now, the polymorphic relationship field is only available in the standard object and it is not possible to create a polymorphic relationship for custom objects in Salesforce. You may want to vote on this idea Custom Polymorphic Id field (WhoId/WhatId) if you think that it is an important feature for you.

1. Click on Name | Setup | App Setup | Create | Workflows & Approvals | Process Builder
2. To create a new process from scratch, click on the New Button available on Process Management page. A popup will appear where you have to enter the Name (Use Auto update case from the task  as name), API Name and Description as shown in the below screenshot:
3. Once you are done, click on the Save button.
4. Click on the Object node to add object and then select the Task object. For the entry criteria, Select when a record is created or edited, as shown in the below screenshot:
5. Once you are done, click on the Save button.
6. The next task is to add Process Criteria, so that process will only fire when a task related to the case is successfully completed. To do this click on Add Criteria, enter Name, Type of action and set filter conditions, and follow the instructions below
   1. For Criteria for Executing Actions, select Conditions are met
   2. Set condition –  [Task].WhatId Starts with ID 500 (case object Identifier)
   3. [Task].WhatId Is null Boolean False
   4. [Task].Status Equals Picklist Completed
   5. [Task].Subject Contains String Case follow-up
7. Once you are done, click on the Save button.
8. Now we have to add an Immediate action into the Process to update the Account Name field. Click on Add Action (Under Immediate actions), Select the type of action (In our case Update Records), and then fill the values into fields to define the action – as shown in the following screenshot:In the preceding screenshot, for the Record Type choose Select a record related to the Task as shown in the following screenshot:
9. Once you are done, click on the Save button. 
10. In the end, your Process will look like the following screenshot:
11. Don’t forget to active the Process by clicking on the Activate button.

It’s time to test this feature

Next time, when a Task related to a Case, with subject Case follow-up, is completed, the process (Created using Process Builder) will fire and update the Case status and description fields.

Note: – I am grateful to Resco.net and Smartcloud.io for sponsoring my blog.

Technical Editor and Proofreader: - Munira Majmundar