What I'm trying to do is in Flow query (Fast Lookup) a Task's TaskWhoRelation records, loop over them to build a new sobject collection of Contact records using the TaskWhoRelation.RelationId, then perform a Fast Update on the built up sobject collection of Contacts.
The part I'm stuck on is that the Assignment element does not let me set the Contact.Id field.
With Winter 18, Salesforce introduced a cool feature to grab the record count directly in the visual flow without the need to loop through it.
After a fast lookup,the record count can be easily fetched in a sobject collection variable and assigned to a number variable. Play around with the number variable directly. So finding out the number of open/closed/in progress opportunities gets more easy. Even you dont need to loop through the record set to get the count of records. You already have it before hand.
So for the above question, you can simply compare if the number variable is having null and decide what to do with it next.
In detail the design looks like this:
Assign the record count to a sObject collections variable. (in screenshot: nofCases)
Use a Assignment step, to assign the variable to a number variable. (Point to note: the assignment variable should be of type number only to make use of equals count operator. In the screenshot, this is called testCount)
Voila! Now play around with the assigned variable :)
Someone pointed this out to me, but I couldn't find it directly in any questions so I wanted to share.
For some reason you cannot assign variables to an SObject, and add that SObject to a SObject collection in the same Assign element. You need to use two different Assign elements, the first to set the variables, and the second to add to the collection. I'm not sure why this is the case, but it has worked for me.
Best Answer
This is a limitation of flows. The Id field is contractually read-only, and so the Flow system won't let you assign a value to the Id field. You will need to use a Fast Lookup or Record Lookup to first query the records you want to update. Even though we wouldn't do this in plain Visualforce/Apex Code (since we already have the ID values), Flows do not allow us to simply call into existence records that are already in the database unless we query them somehow. The alternative to this, which I feel defeats the purpose of using flows, would be to create an InvocableMethod and a series of InvocableVariable declarations, and create the objects in Apex Code.