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Power Automate - Building Flows
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Daily Variable Increment on New Email Trigger

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Posted on by 26

Hello, I have a flow that saves email attachment (on new email trigger, usually 1 attachment per email) to FTP. I would like the file name to be FileName#, where # increments from 1 but resets every day at midnight. Since there is no global variables, and I have a basic free account only (no SharePoint, OD for Business), I can't seem to find where to initialize/store the counter variable. I can increment it successfully - if email has multiple attachment, file names are 1, 2, 3... but since the variable is initialized inside the flow, it resets to 1 every time the flow starts (e.g. new email is received). Is upgrading the account my only option or is there a trick I haven't seen yet?

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  • Ed Gonzales Profile Picture
    4,531 Most Valuable Professional on at
    Re: Daily Variable Increment on New Email Trigger

    @JojoS 

    Hi there.  Do you have the date in the filename somehow?  I imagine something like that since each day you'd have a new file #1, right?  Here's my thought:

     

    • Make your filename something like this:  yyyyMMdd_xxx where xxx is your increment number.
    • At the beginning of your flow, have a step to list the files in a folder (If there's an option for an OData filter in that action, you can 'pre-filter' the list by anything that begins with today's date in yyyyMMdd format.
    • If there's no OData filter on the FTP action, then add a Filter Array step.
    • A condition to see if the array is empty.  If yes, then your increment number is 1 or whatever the first in your series is.
    • In the No path (meaning the filter array is NOT empty), we can use split() to parse out the increment numbers, then sort that array... and then take the last element.
    • That number will be the base for your increment steps that you've already got in place.

    I won't have time today, but tomorrow I'll work on building something and documenting it, but let me know if you want me to go into more detail in any of the steps.  It's tough to tell where folks are at on the learning journey.

     

    Keep us posted.

    -Ed

     

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  • JojoS Profile Picture
    26 on at
    Re: Daily Variable Increment on New Email Trigger

    Thank you for your reply on Sunday.

    The file name should not have a date at all. The final file name will simply be image_1, image_2 and so on. The goal is also to not delete the files but rather overwrite them the next day.

    I think I get your idea (basically purge the current FTP files and increment from there) but because I am trying to avoid having date in the file name, it will not work.

  • Ed Gonzales Profile Picture
    4,531 Most Valuable Professional on at
    Re: Daily Variable Increment on New Email Trigger

    @JojoS,

    Hey there.  Intent wasn't to purge, I just didn't know you wanted to overwrite existing files.  But...  if day 1 has 3 images, and day 2 only has 1, there will be two images in that folder that weren't from day 2.  Does that matter in your process?

     

    -Ed

  • JojoS Profile Picture
    26 on at
    Re: Daily Variable Increment on New Email Trigger

    I used "purge" improperly. I meant to say parse.

     

    I might be able to change somethings around delete all images at the end of the day. I will be experimenting this week. If you have time, drop a few details about your original suggestion - reading the FTP files and moving the file name to array (split with '_') so the next value for increment can be determined.

     

    Thanks.

  • Ed Gonzales Profile Picture
    4,531 Most Valuable Professional on at
    Re: Daily Variable Increment on New Email Trigger

    @JojoS 

    Well, if you're not worried about the date, then you can just have the number be the filename right, then we'll use split() to get everything before the period and make that your array.  I'm trying to figure out how to make an FTP server right now, but I'll probably be able to build something tomorrow.

    -Ed

  • Verified answer
    Ed Gonzales Profile Picture
    4,531 Most Valuable Professional on at
    Re: Daily Variable Increment on New Email Trigger

    @JojoS 

    Actually, I came up with something much simpler.  Two different flows, but the core of both is a simple text file in your FTP folder called something like FileMax.txt.  The file contents could be something as simple as varFileName = 0.

     

    The first flow has a recurrence trigger that runs at midnight every night, followed by an FTP Update File action.
    20200817a.PNG

    (I realized after I posted this, that I have two different file contents.  Pretend the one above says "varFileName = 0")

     

    That will reset the counter back to zero each day.

     

    The second flow is your thing just as you had it, but we'll set the initial number by using the FTP Get file content action and point it to your text file.  That will get you "varFileName = 0" which we can parse and add 1 to all in one step.  Put a compose after the get file content with this expression:

     

    add(int(split(body('Get_file_content'),' = ')[1]),1)

     

    Here's an explanation of that, and also a video on the Split() function:

    20200817b.PNG

     

    • Then you want to update your text file with the new starting number from the output of the compose above.  You can do this with an FTP Update File and in the File Content area, just have "varFileName = " and then the dynamic output from your compose above.  It should look like this:

    20200817c.PNG

     

    Which will update the text file and ready it for the next file:

    20200817d.PNG

     

    Give that a go, hopefully it's enough to get you going in the right direction.  Keep us posted either way.

    -Ed

     

    If you liked this reply, please give it a thumbs up! If this reply has answered your question or resolved your challenge, please consider marking it as a Solution. This helps other users find it more easily via search.

     

  • JojoS Profile Picture
    26 on at
    Re: Daily Variable Increment on New Email Trigger

    I can't believe I missed this. Exactly what I needed.

    I actually expanded this and did slightly different logic (my case was broader than I explained. I increment the counter in a varriable called 'CounterCh1'. It does increment but it fails to write the file as I expected.

     

    I am asking it to do this (CounterCh1 is int '1' at this point):

    JojoS_0-1597716084877.png

     

    I am expecting to see

    Ch1Counter-1-

    but instead, the file get's written with:

    Ch1Counter-@variables('CounterCh1')-

     

    Do you know why?

     

  • Ed Gonzales Profile Picture
    4,531 Most Valuable Professional on at
    Re: Daily Variable Increment on New Email Trigger

    Try wrapping your dynamic value with single quotes and let me know if that works.  If so, I'll need to adjust the article I just wrote 😛

     

    20200817j.PNG

     

    Here's a link to the article for more detail: Modeling a Global Variable Without Variables in Power Automate / Flow

     

    Keep us posted.

    -Ed

     

    If you liked this reply, please give it a thumbs up! If this reply has answered your question or resolved your challenge, please consider marking it as a Solution. This helps other users find it more easily via search.

  • JojoS Profile Picture
    26 on at
    Re: Daily Variable Increment on New Email Trigger

    Nope. All it did is added quotes:

    JojoS_0-1597716764539.png

    @edgonzales 

  • JojoS Profile Picture
    26 on at
    Re: Daily Variable Increment on New Email Trigger

    And same results when using Output of compose.

    JojoS_0-1597772682442.png

     

    @edgonzales 

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