Multi-Way Sync to Multiple SharePoint Lists without Infinite Loop

[the_joey_o]

I'm working with several different lists, and I'm trying to sync their content such that if an item in List A is updated, the corresponding item is updated in Lists B, C, D, and E. If an item is updated in List B, it is updated in List A, C, D, and E. If an item is updated in List C, it is updated in List A, B, D, and E. And so on. However, All of my attempts thus far have resulted in infinite loops. How would I go about achieving this?

[v-xida-msft]

Hi @the_joey_o,

Could you please share a screenshot of your flow's configuration?

Do you create multiple separated flows on your side?

Further, do your several different lists have same data structure?

I suppose that you created multiple separated flows on your side based on several different SharePoint lists and you use "When an item is created or modified" trigger as the trigger of your flow. In addition, I think your several different lists have same data structure, is it true? I think the issue that you mentioned is related to your flow.

If the List A is updated, you use the "Update item" action to update List B, C, D and E. The "Update item" action would also trigger the flow which monitor if there is an item updated in List B, C , D and E (The List Name field set to List B, C, D and E within "When an item is created or modified" trigger).

If you want to avoid this infinite loops, you could consider take a try with the following workaround:

I have created a SharePoint list on my side and the data structure of it as below:Note: The TaskName column is a Single line of text type column, Due Date column is a Date type column and the UpdateFromOtherFlow column is a Yes/No type column. The default value of UpdateFromOtherFlow column is No. The UpdateFromOtherFlow column indicated that if the modification of an item comes from other flows, please create this column on your several different SharePoint lists.

I have made a test on my side (make a test on two different lists) and please take a try with the following workaround:

• Add a "When an item is created or modified" trigger, specify Site Address, List Name set to List A.
• Add a Condition, click "Edit in advanced mode", type the following formula:

@equals(triggerBody()?['UpdateFromOtherFlow'], false)

• Within "If/yes" branch of Condition, add a "Get items" action, specify Site Address, List Name set to List B. Add a "Filter array" action, From set to output of "Get items" action, click "Edit in advanced mode", type the following formula:

@equals(item()?['TaskName'], triggerBody()?['TaskName'])

     Add a "Apply to each" action, input parameter set to output of "Filter array" action. Within "Apply to each" action, add a "Update item" action, specify Site Address, List Name set to List B. Id field set to following formula:

item()?['ID']

Title field set to following formula:

item()?['Title']

TaskName field set to TaskName dynamic content of the trigger, Due Date field set to Due Date dynamic content of the trigger. The UpdateFromOtherFlow field set to Yes.

Image reference:

The flow works successfully as below:

Best regards,

Kris

[pradeep_khanna]

@the_joey_o , I am sorry if my answer is too naive, but unless there is a desperate Need to keep the two lists Synchronous in Real-Time, you can think of a time-based trigger: run the task every day or twice a day or so on (you can choose the periodicity). Compare each item on modified date, and whichever one has a more recent update date-time stamp, feed that into the other list. Alternately (Slower performance, and depending on number of columns in metadata), you compare field-on-field, using "Get Changes of an Item or a File (properties only)". This should work for most cases, unless you have two lists popular enough to have Many-many changes every minute.

[Anonymous]

@pradeep_khanna What you have outlined is what I thought would be a far simpler approach. I just haven't quite figured out how to do it and haven't found any resources guiding how to do it. You are the first person that has put this approach forward that I have been able to find :).

I have an active real-time update for the master list to child list, but there is a requirement from users to be able to update the child list and have it flow back to the master. The once/twice per-day compare each item on modify date/time stamp is what I would like to implement. Do you have any links to any resources that explain how to do that? 

[pradeep_khanna]

Here's what I'd do:

1. On both lists that need to be in Synch, introduce a date-time column "Last Synched"
2. Create a flow that will run hourly (Or whatever frequency works best for you to balance business requirement & resource efficiency)
   
3. Two Methods from here on...
   1. Get All Changes:
      1. Read list items where Last Synched < Modified date
      2. Move all column values from all common columns from one list to the other
   2. Update ONLY IF some specific columns have been changed:
      1. Use the "Get Changes" template:
         
      2. Loop on the fields of the list, pick up the deltas, update them across the lists
4. Before you exit the workflow, update the "Last Synched" field

PS: If there is simply a parent-child relationship where you are trying to inherit data from the parent to the child list, you may want to explore a simple "Lookup Column" before you get into this complexity

[Anonymous]

Hey thanks Pradeep. I'll give it a go and see if I can get it to work.

I've used lookups extensively between different lists and it is very handy functionality.

My Parent/child description was probably a bit wrong there. There are 2 lists (lets call the List A and List B) that feed values into a 3rd List C (which also has direct inputs), but a full sync back from List C to list A when List A values are changed, and the same for List B values in List C that have been edited, writing back into List B.

Thanks again for the response, much appreciated.