Not able to setup lookup value to null in power automate

Hi All,

I am listing an entity records which is being used to create a duplicates  of all listed records using power automate flow.

Now, the problem is this entity has got 5 lookup fields to populate to the new duplicates records, when it has got the value I am able to populate and create a new records. But not when it has null value. I cannot add the if else as it will have a lot of branching and look bad.

For example,

When contact lookup has got the value then I am using this expression and its working fine-

/contacts(Dynamic value)

 When it has null value then I am using and its giving error or blank contact even if it has contact

if(empty(items('Apply_to_each')?['body/_new_contact_value']), ' ',
concat('contacts(',items('Apply_to_each')?['body/_new_contact_value'],')'))

I cannot use the below expression as suggested by other members as I am fething record form APPLY to each

if(empty(triggerOutputs()?[‘body/_parentcustomerid_value’]), ‘ ‘,
concat(‘accounts(‘, triggerOutputs()?[‘body/_parentcustomerid_value’],’)’))