Shed some light on arrays or collections in Power Automate

Are you struggling with arrays in Power Automate? This post will help you master arrays.

Power Automate arrays and collection

Today I was asked about how arrays (aka collections) work in Microsoft Flow. In this post I will shed some light on arrays and many of the common scenarios that you may face with arrays in Power Automate.

I will start with creating arrays, then I will look at manipulating arrays, but first of all what are arrays?

In most common programming languages you will recognize the term array as a block of related data elements. You could see this as a table or a list list alike data structure.

Creating arrays

I’m going to start with the following table of data.

I want to create an array like the above table.

In flow I could now create an array using the createArray function.

createArray('Nissan','Citroen','Audi')

I could even take this further and create arrays in arrays.

createArray(createArray('Nissan','Red',3,'01/07/2015'),createArray('Ctiroen','Green',2,'21/09/2016'),createArray('Audi','Blue',4,'01/07/2014'))

Nested Arrays in Json

And I will get an array of arrays

[
  [
    "Nissan",
    "Red",
    3,
    "01/07/2015"
  ],
  [
    "Citroen",
    "Green",
    2,
    "21/09/2016"
  ],
  [
    "Audi",
    "Blue",
    4,
    "01/07/2014"
  ]
]

Now that we know how to create arrays, it is time to do something with all these arrays.

Where do I find arrays in flows?

Within Flow you can find arrays everywhere. The most common place and most visible place is within the Apply to each step. In this step flow will take an array and step through the elements in the array. So If we take a further look at the previous example then a Compose delivering an array can split by an Apply to each step:

As Power Automate is running through the Apply to each you will find the separate elements of my array.

So far this post is all about creating arrays and then stepping through arrays. Now that we have some basic understanding of arrays in Flow it is time to get some real arrays. For this I’m going to create a list in SharePoint with the same data as in the above table.

Using the Get Items action from the SharePoint connector I can now read the data from this list.

Looking at the Body of the Get Items action you will see some json as shown below:

{
  "value": [
    {
      "@odata.etag": "\"1\"",
      "ItemInternalId": "1",
      "ID": 1,
      "Title": "Nissan",
      "Colour": {
        "@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedReference",
        "Id": 0,
        "Value": "Red"
      },
      "Colour#Id": 0,
      "Age": 3,
      "Registration_x0020_Date": "2015-01-07",
      "Modified": "2018-07-10T08:36:27Z",
      "Created": "2018-07-10T08:36:27Z",
      "Author": {
      "@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
      "Claims": "i:0#.f|membership|pieter@pieterveenstradev.onmicrosoft.com",
      "DisplayName": "Pieter Veenstra",
      "Email": "pieter@PieterVeenstraMVP.onmicrosoft.com",
      "Picture": "https:/ /pieterveenstraMVP.sharepoint.com/_layouts/15/UserPhoto.aspx?Size=L&AccountName=pieter@PieterVeenstraMVP.onmicrosoft.com",
      "Department": null,
      "JobTitle": null
    },
    "Author#Claims": "i:0#.f|membership|pieter@pieterveenstradev.onmicrosoft.com",
    "Editor": {
       "@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
       "Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
       "DisplayName": "Pieter Veenstra",
       "Email": "pieter@PieterVeenstraMVP.onmicrosoft.com",
       "Picture": "https:/ /pieterveenstraMVP.sharepoint.com/_layouts/15/UserPhoto.aspx?Size=L&AccountName=pieter@PieterVeenstraMVP.onmicrosoft.com",
       "Department": null,
       "JobTitle": null
    },
    "Editor#Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
    "{Identifier}": "Lists%252fCars%252f1_.000",
    "{Link}": "https://pieterveenstradev.sharepoint.com/_layouts/15/listform.aspx?PageType=4&ListId=51c5fad6-6c45-4bc4-8632-556674abe0be&ID=1&ContentTypeID=0x01004819843C002BE14D97CADA4CCA608281",
    "{Name}": "Nissan",
    "{FilenameWithExtension}": "Nissan",
    "{Path}": "Lists/Cars/",
    "{HasAttachments}": false
  },
  {
     "@odata.etag": "\"1\"",
     "ItemInternalId": "2",
     "ID": 2,
     "Title": "Citroen",
     "Colour": {
     "@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedReference",
     "Id": 2,
     "Value": "Green"
   },
   "Colour#Id": 2,
   "Age": 2,
   "Registration_x0020_Date": "2016-09-23",
   "Modified": "2018-07-10T08:37:04Z",
   "Created": "2018-07-10T08:37:04Z",
   "Author": {
   "@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
   "Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
   "DisplayName": "Pieter Veenstra",
   "Email": "pieter@PieterVeenstraMVP.onmicrosoft.com",
   "Picture": "https://pieterveenstraMVP.sharepoint.com/_layouts/15/UserPhoto.aspx?Size=L&AccountName=pieter@PieterVeenstraMVP.onmicrosoft.com",
   "Department": null,
   "JobTitle": null
 },
   "Author#Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
   "Editor": {
     "@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
     "Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
     "DisplayName": "Pieter Veenstra",
     "Email": "pieter@PieterVeenstraMVP.onmicrosoft.com",
     "Picture": "https://pieterveenstraMVP.sharepoint.com/_layouts/15/UserPhoto.aspx?Size=L&AccountName=pieter@PieterVeenstraMVP.onmicrosoft.com",
     "Department": null,
     "JobTitle": null
   },
   "Editor#Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
   "{Identifier}": "Lists%252fCars%252f2_.000",
   "{Link}": "https:/ /pieterveenstradev.sharepoint.com/_layouts/15/listform.aspx?PageType=4&ListId=51c5fad6-6c45-4bc4-8632-556674abe0be&ID=2&ContentTypeID=0x01004819843C002BE14D97CADA4CCA608281",
   "{Name}": "Citroen",
   "{FilenameWithExtension}": "Citroen",
   "{Path}": "Lists/Cars/",
   "{HasAttachments}": false
},
{
"@odata.etag": "\"1\"",
"ItemInternalId": "3",
"ID": 3,
"Title": "Audi",
"Colour": {
"@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedReference",
"Id": 1,
"Value": "Blue"
},
"Colour#Id": 1,
"Age": 4,
"Registration_x0020_Date": "2014-01-01",
"Modified": "2018-07-10T08:37:42Z",
"Created": "2018-07-10T08:37:42Z",
"Author": {
"@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
"Claims": "i:0#.f|membership|pieter@pieterveenstradev.onmicrosoft.com",
"DisplayName": "Pieter Veenstra",
"Email": "pieter@PieterVeenstraMVP.onmicrosoft.com",
"Picture": "https://pieterveenstraMVP.sharepoint.com/_layouts/15/UserPhoto.aspx?Size=L&AccountName=pieter@PieterVeenstraDev.onmicrosoft.com",
"Department": null,
"JobTitle": null
},
      "Author#Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
      "Editor": {
        "@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
        "Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
        "DisplayName": "Pieter Veenstra",
        "Email": "pieter@PieterVeenstraMVP.onmicrosoft.com",
        "Picture": "https://pieterveenstraMVP.sharepoint.com/_layouts/15/UserPhoto.aspx?Size=L&AccountName=pieter@PieterVeenstraDev.onmicrosoft.com",
        "Department": null,
        "JobTitle": null
      },
      "Editor#Claims": "i:0#.f|membership|pieter@pieterveenstraMVP.onmicrosoft.com",
      "{Identifier}": "Lists%252fCars%252f3_.000",
      "{Link}": "https://pieterveenstraMVP.sharepoint.com/_layouts/15/listform.aspx?PageType=4&ListId=51c5fad6-6c45-4bc4-8632-556674abe0be&ID=3&ContentTypeID=0x01004819843C002BE14D97CADA4CCA608281",
      "{Name}": "Audi",
      "{FilenameWithExtension}": "Audi",
      "{Path}": "Lists/Cars/",
      "{HasAttachments}": false
    }
  ]
}

This is where the data in Power Automate can become difficult to understand. The above JSON might need a second look before you really understand what data can be found. json can be difficult to understand, especially when a lot of json is thrown at you. Flow is making your life easy here! Use dynamic content and often you can forget about the json, you simply get your SharePoint list columns back. It even helps you with the complexities around lookups, dates and other column types.

Array functions

Time for a step into the deep end. There is a lot more we can do with arrays. I’m going to start with the arrays functions available within Microsoft Flow. You will notice that in the referenced article the term Collections is also used.

Hey, I want to do more! Where is the sort function?

Well remember when we got the data from my SharePoint list? In the Get Items action you can sort your data. So you might want to sort your data when you collect your data.

Also in the Data operations connector there is no sort:

If you need to sort your array however, please have a look at Sort an array or collection in Power Automate

The examples of functions on Arrays

In this section I will look at operations you can do on arrays such as join, select and filter.

Contains

The contains functions checks your array for any values or elements in your collection or array.

Looking at the following 3 examples. The first 2 return false where the last one returns true.

contains(body('Get_items')?['Value'],'Nissan')

contains(outputs('Compose'),'Nissan')

contains(first(outputs('Compose')),'Nissan')

Within the last example I selected a single record from my array before checking with the contains function for my car brand. Where in the first two examples I’m supplying an array of array to the contains function.

Empty

Empty checks the length of the Collection if no items are found in the array then true is returned. Note that this is not the same as comparing an array to a null value.

First item in collections

The First function returns the first item from the collection. See the 3rd example from the contains section above for a real example.

You could also user the construction array[0] to get to the first item, however when the array isn’t defined you will find that your flows will error while first returns a null value.

Intersection

Imagine that you have two arrays and you want to get the items that exist in both collection. and Now you want to find the items that exist in both collections.

So you could for example have two lists with cars. One list is called my cars and one is called insured cars if you now want to find out which of your cars are insured you could use the intersection function.

intersection(body('Get_items')?['Value'],body('Get_items_2')?['Value'])

Join collections

When you have an array of strings and you would like to create a character separated list of strings then you could do this with the join function. Have you ever has a list of users in SharePoint and you wanted to email them all?

join(outputs('Compose'),';')

Last item in collections

The last function is similar the the first function, other than that you get the last element in the array rather than the first one.

Length of collections

The length function gives you the number of elements in a collection. Nothing exciting here.

Skip

With the skip function you can select all elements after a certain position.

skip(outputs('Compose'),2)

Take

The take function is similar to the skip function but now you can collect all the elements up to a certain point in your array.

take(outputs('Compose'),2)

Union

In my earlier examples I had two arrays in my json. One that I manually created and and one that I get from the Get Items action. To merge these arrays into one array you could run the following:

union(body('Get_items')?['Value'],outputs('Compose'))

Did you notice that Flow really doesn’t care that these two arrays are not exactly the same. As Flow will just consider these two arrays to be JSON. It is just gluing the two collections of data together. this is where a sort might be important, although most of the times you will find that you will just want to process each element in your collection and the order really doesn’t matter.

Select

The select action I also want to include here. Although Select is not a function within Power Automate it can help you transform an array of elements.

Taking an input array and transforming the arrays using a select often helps improve the processing of arrays.

Filter arrays

If you want to filter your array or collection data in Power Automate then please have a look at my filter data in arrays using the select action posts. I that post I’m giving more details on filtering data using the select.

Often it can be wise to filter an array first before pushing it through an apply to each. For performance reasons this is definitely worth a look. It is quite easy to gain multiple minute in the run of a flow.