Power automate Flow, Do not create new records if they exist

Question

How can I not create duplicates with my flow? I want to create records from List A into List B IF they don't already exist in B, if they already exit, DO NOT create them, as it is creating duplicates.

I've added the condition to check if item exists and then if it exists do not write:

length(outputs('Get_Items')?['body/value'])

However this does not work and does not create any records even if the list is empty.

Filter query:

Center eq 1463 and (AutomationType eq 'Management Reporting' or AutomationType eq 'Testing') and Repeatable eq 'Yes'. 

all these values are from list A.

Any help would be appreciated.

possible change:

Answer 1

As you want to create items in List B based on items in List A, you have to check the length condition based on items in List B (not List A).

So, before using Create item action, you have to get the list items from list B for specific filter condition. Then based on items returned, you can check length of decide if you want to create item or not.

Here's example for this:

You have to do this for each item in List A.

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Update from comments:

Here is the full flow configuration which should work for your requirements:

Answer 2

If Request_ID is a parameter passed from the flow trigger, you cannot just use Request_ID, because you need the context of the trigger.

I suggest you initialise a variable varRequestID, set it to the trigger parameter value and then use the variable in the filter query. Note that you must wrap the variable in single quotes, too!!

Here is the screenshot:

Of course you can directly use the dynamic content reference in the Filter Query, but if you go via a variable, you can more easily inspect it in the flow run.

Screenshot of direct reference. Note the single quotes around the request id property!!