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Compose actions inside apply to each steps in Power Automate

Compose actions inside apply to each steps in Power Automate

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Pieter Veenstra

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Today I came across  a weird feature in Microsoft Flow. I collected a list of files from SharePoint and I was setting a Compose with the title of my files.

Reference Compose inside an apply to each

In the run history each file was listed and I was quite happy with this. Inside the apply to each step can use this value.

Get Files action giving 10 files in compose in Apply to each

But what if I use this outside the Apply to each after the Apply to each has finished. To my surprise I was getting an array back.

Compose following apply to each containing array

My first thought was: “That is annoying. That can’t be right!”

But you could use this to filter your arrays.

Filter array

With the condition set to:

startsWith(outputs('Compose_-_File_name'),'t')

This now resulted in an array just giving me the files starting with the letter t.

However I found that the array returned looked like this:


[null,"text","test2",null,"tf78062375",null,null,null,null,null]

Concurrency

It looks like the compose actions inside the apply to each steps are created as an array. Why?

Although by default the Concurrency is switched of on every Apply to each step. It is possible to enable this.

To make sure that things don’t go wrong you could switch this off, however I have found recently that the order of the items is not affected by the Concurrency feature. Performance wise the concurrency feature can really make a difference.

Concurrency control

The advanced method

Do you want to take this method further, then read The advanced Pieter’s method in Power Automate

Is your business still running on paper trails, sprawling Excel files, or ageing Access databases? There’s a better way — and I can show you exactly what it looks like. I’m the Technical Director of Vantage 365, a Microsoft solutions consultancy working with clients across the UK, the Netherlands, and worldwide. For over 30 years I’ve been turning messy, manual business processes into clean, automated systems that save time, reduce errors, and give teams the visibility they need to make better decisions. SharePains is not just any blog run by a Microsoft MVP. Have you ever used Try-Catch in Power Automate? The original post about Try-Catch in Power Automate can still be found on this site, https://staging.sharepains.com/2018/02/07/try-catch-finally-in-power-automate-flow/ Or have you ever used the Pieter’s method to avoid variables and speed up your flows? https://staging.sharepains.com/2020/03/11/pieters-method-for-advanced-in-flows/ You can contact me using contact@staging.sharepains.com

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13 responses to “Compose actions inside apply to each steps in Power Automate”

  1. Manish Jain Avatar
    Manish Jain

    Hi Pieter,

    I am facing a weird scenario where I am using the same functionality but outputs(‘compose’) is giving me null. Is there any specific condition that needs to be fulfilled for outputs(‘compose’) to work after setting in Apply to each loop.

    Thanks

    1. Pieter Veenstra Avatar
      Pieter Veenstra

      Compose need to match the name of the compose action.

      So most likely

      outputs(‘Compose’) instead of outputs(‘compose’)

  2. Manish Jain Avatar
    Manish Jain

    I checked it but it still not working.

  3. Stuart Avatar
    Stuart

    Has this changed? When I try this now, and Compose actions inside an Apply to Each are not available at all outside the loop.

    1. Pieter Veenstra Avatar
      Pieter Veenstra

      Hi Stuart,

      Within Dynamics content they are not available but if you type in the expression editor the following expression then it will work:

      outputs('name_of_the_action_inside')

  4. BeyondTheBox Avatar
    BeyondTheBox

    An array is an interesting but probably not an unexpected outcome. Look at how the Apply-to-each displays the results for each step. Technically, that is an array. So I am not surprise that after the loop the compose inside the loop became an array.

  5. Claudia Avatar
    Claudia

    Hi Pieter,

    I have tried to create a compose action, out of “Apply to each” action, but I receive the following error:

    Flow save failed with code ‘InvalidTemplate’ and message ‘The template validation failed: ‘The inputs of template action ‘Compose_3’ at line ‘1 and column ‘22174’ cannot reference action ‘Parse_JSON_-_xxxx’. The action ‘Parse_JSON_-_xxxxx’ is nested in a foreach scope of multiple levels. Referencing repetition actions from outside the scope is supported only when there are no multiple levels of nesting.’.’.

    Thank you
    Claudia

    1. Pieter Veenstra Avatar
      Pieter Veenstra

      HI Claudia,

      This method only works when you don’t have nested Apply to each steps. You can avoid nested apply to each steps by creating child flows.

      1. Beyond the Box Avatar
        Beyond the Box

        You can also overcome this crazy limitation by composing the results of each iteration and then inserting that data into a variable while the loop is running. Even this is tricky as it seems traditional variable actions in an apply-to-each loop do not work as expected. Instead, you have to compose the results in each iteration to include all previous iterations. Then set a variable with the cumulative compose output. I am experimenting now to see if the same limitation exists with Do-Until loops but this approach will likely also require the use of variables (which I try to avoid since Microsoft has not made them flow friendly).

  6. Harold Anderson Avatar
    Harold Anderson

    Could you please tell me the general principle here? If you use a compose inside a loop, what happens? Does the compose additively join successive values together, creating an array of the items you called compose with? I’m sorry I can’t follow what you’re trying to say.

    1. Pieter Veenstra Avatar
      Pieter Veenstra

      That is exactly what happens. The objects in the apply to each are merged into an array.

  7. Scott Avatar
    Scott

    One huge limitation to this is that it ONLY works with a single level of nested loops. It will NOT work if the Compose is nested inside multiple loos, even if you try to access it only one level from the loop it is in. You get an error.

    “Flow save failed with code ‘InvalidTemplate’ and message ‘The template validation failed: ‘The inputs of template action ‘Compose_2’ at line ‘1 and column ‘2688’ cannot reference action ‘ComposeTaskStatus’. The action ‘ComposeTaskStatus’ is nested in a foreach scope of multiple levels. Referencing repetition actions from outside the scope is supported only when there are no multiple levels of nesting.’.’.

    This is unfortunate, because this is EXACTLY the scenario (where I will have to create, manage, and cleanup a bunch of variables) where I need this capability to make my code cleaner.

    1. Pieter Veenstra Avatar
      Pieter Veenstra

      This method can almost always work though even when you have nested processes. All you need to do is use Child flows to run the steps inside your apply to each. Then you can use the method described inside the child flow.

      Using child flows instead of nested apply to each flows is a good performance improver too. Personally I never nest apply to each steps.

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