3 Ways

3 Ways to add a column to an array in Power Automate

When you have an array in Power Automate and you would like to add a column, you have 3 ways of doing this.

Arrays in Power Automate

In some of my posts in the past I already looked at arrays. In this post I will look at the different ways of adding a column to my array. I’ve found a number of ways of doing this and they all have their advantages.

  • Constructing raw json
  • Using AddProperty
  • Using a select action

In my examples I’m going to use a compose action to create my initial array. But the arrays can really come from any other data source. This could be a SharePoint list, a SQL database or a table in Dataverse or anything else. Arrays are everywhere.

Creating the initial array

I’m creating the initial array, with two objects

3 Ways to add a column to an array in Power Automate Microsoft Office 365 Create an array using a compose action

Then as a run my flow I’m getting an array

3 Ways to add a column to an array in Power Automate Microsoft Office 365 array created

Ok, that is good. Now I want to add the length of each title to the array.

Add a column to an array

The first option is to construct the objects inside an apply to each and then adding the Length property followed by an expression that calculates the length.

length(items('Apply_to_each')?['Title'])
3 Ways to add a column to an array in Power Automate Microsoft Office 365 image 8

That is easy enough when you only have one property to replicate and it also work probably when you have an array that has predictable propeties, but not every object in each array has to be the same, so this might be some thing that doesn’t always work.

If you have many unpredictable properties in your array you could consider the AddProperty function

AddProperty

3 Ways to add a column to an array in Power Automate Microsoft Office 365 image 9

Using the following expression you can add a column to whatever object you want. Giving the same result.

addProperty(items('Apply_to_each_2'),'Length', length(items('Apply_to_each_2')?['Title']))

The fast road to an additional column

Now you could use a select action and replicate all the properties, but that has got that same problem again of managing optional properties.

3 Ways to add a column to an array in Power Automate Microsoft Office 365 image 10

Using the addProperty in the select can be really powerful.

Add a column to an array

With the following expression we’re taking each item in the array and adding our property.

addProperty(item(),'Length', length(item()?['Title']))

Advantages of this last option. Only 1 action used, it is fast and it is easy to understand.

3 Ways to add a column to an array in Power Automate Microsoft Office 365 image 12

5 thoughts on “3 Ways to add a column to an array in Power Automate

  1. Hi Peter, Great article. I have always found your blogs very helpful. I am dealing with strange issue with my flow when concurrency control is enabled for the “Apply to each”. I am wondering if you are able to assist me.

    I have a flow that processes approximately 3,000 records every night. Let’s assume that these records are in an array like below:

    [
    {
    “ID”: 1,
    “Name”: “John Walker”
    },
    {
    “ID”: 2,
    “Name”: “Mary Flynn”
    },


    {
    “ID”: 3000,
    “Name”: “Jane Doe”
    }
    ]

    I need to lookup for all phone numbers available for each record, and update the above array or create new array like the following:

    [
    {
    “ID”: 1,
    “Name”: “John Walker”,
    “Home Phone”: “415-897-0998”,
    “Work Phone”: “650-098-3443”,
    “Mobile Phone”: “210-783-9098”
    },
    {
    “ID”: 2,
    “Name”: “Mary Flynn”,
    “Home Phone”: “453-873-0833”,
    “Work Phone”: “515-212-4532”,
    “Mobile Phone”: “301-463-7897”
    },


    {
    “ID”: 3000,
    “Name”: “Jane Doe”,
    “Home Phone”: “415-897-0998”,
    “Work Phone”: “650-098-3443”,
    “Mobile Phone”: “210-783-9098”
    }
    ]

    Phone numbers are in a separate array in the following format:

    [
    {
    “ID”: 1,
    “Phone Number”: “415-897-0998”,
    “Type”: “Home Phone”
    },
    {
    “ID”: 1,
    “Phone Number”: “650-098-3443”,
    “Type”: “Work Phone”
    },
    {
    “ID”: 1,
    “Phone Number”: “210-783-9098”,
    “Type”: “Mobile Phone”
    },
    {
    “ID”: 2,
    “Phone Number”: “453-873-0833”,
    “Type”: “Home Phone”
    },
    {
    “ID”: 2,
    “Phone Number”: “515-212-4532”,
    “Type”: “Work Phone”
    },
    {
    “ID”: 2,
    “Phone Number”: “301-463-7897”,
    “Type”: “Mobile Phone”
    },
    {
    “ID”: 3000,
    “Phone Number”: “415-897-0998”,
    “Type”: “Home Phone”
    },
    {
    “ID”: 3000,
    “Phone Number”: “650-098-3443”,
    “Type”: “Work Phone”
    },
    {
    “ID”: 3000,
    “Phone Number”: “210-783-9098”,
    “Type”: “Mobile Phone”
    }
    ]

    My flow works fine if the concurrency control is disabled but it takes approximately 6 hours to complete the run. If concurrency control is enabled with degree of parallelism of 50, it takes about 1 hour. But the results are not accurate as the phone numbers are mixed up between the records. i.e. Mary’s home phone is listed for John’s mobile, John’s work phone is listed for Jane’s work..etc.. Any idea on how I can build an array that has the following:

    ID:
    Name:
    Home Phone:
    Work Phone:
    Mobile Phone:

    Thank you!

      1. Thank you for your prompt response, Pieter. The post you referenced is exactly how I wrote my flow. I read the post and learnt from it. The only difference is that my flow has nested “Apply to each” loop after filtering the array. The filter array in my case returns multiple records. I need to use “Apply to each” to go through each record to extract phone number and type. Again, my flow works fine with no concurrency enabled but it takes very long time to finish the job. Any idea what might be the problem?

      2. Hi Pieter,

        I am struggling to figure this out with the Select action. How would I convert the following array into something like this? If you have any posts, please refer. I would greatly appreciate your idea on this.

        Desired Array:
        [
        {
        “Name”: “John Doe”,
        “Home Phone”: “”,
        “Work Phone”: “334-233-2323”,
        “Mobile Phone”: “”
        },
        {
        “Name”: “Jane Doe”,
        “Home Phone”: “455-234-1212”,
        “Work Phone”: “565-234-1212”,
        “Mobile Phone”: “121-222-1212”
        }
        ]

        Source Array1:

        [
        {
        “Name”: “John Doe”
        },
        {
        “Name”: “Jane Doe”
        }
        ]

        Source Array2:
        [
        {
        “Name”: “John Doe”,
        “Type”: “Work Phone”,
        “Number”: “334-233-2323”
        },
        {
        “Name”: “Jane Doe”,
        “Type”: “Home Phone”,
        “Number”: “455-234-1212”
        },
        “Name”: “Jane Doe”,
        “Type”: “Work Phone”,
        “Number”: “565-234-1212”
        },
        “Name”: “Jane Doe”,
        “Type”: “Mobile Phone”,
        “Number”: “121-222-1212”
        }
        ]

        Thanks,

        Buddha

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