How can I use expressions to reduce array of objects

Question

I am in the process of creating a flow which, upon the trigger activating, sends a prompt to a user.

The user selects a response, and then the flow sends a message in the appropriate channel. The prompt items come from the list channels action. I can use body('ListChannels')?['value] to parse the response. The response is an array with each object looking like:

{
  "id":"",
  "displayName":"General",
  "description":"Used to test in-development features",
  "email":"",
  "webUrl":""
}

I want to reduce each object to just the displayName key and use the resulting as the inputs for the next action, this is the accepted input for that action: ["General", "Channel2", "Channel3"]

Is there a way to convert this using the provided expressions/actions for power automate? I also need to use the response to lookup the corresponding array entry "id" for sending a message to that channel.

Answer 1

One possibility is to use looping and control statements to perform 'reduce' and 'lookup' actions:

For reduce : Initialize variable(s) (array) first and push the lookup value to the array(s):

Since the input for the next action requires options that are readable to the user we have to use the channel name.

For lookup : Loop through the original object array and compare each object channel name to your query value:

The user response is stored in selectedResponse . We can loop through each item from the original list channels response and compare this to each objects channel name. If there is a match. We can use the current items id as the argument to the "Post your own adaptive card" action.

Result :