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Flow Converting Null to Empty String

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First post, but I have been using PA for a while. I have a flow created where I am trying to update an existing list item when an item in a different list is updated. A few of the fields to be updated are date fields (date only) and this is where I am having trouble. The values in these three fields are driven off a fourth "Project End Date" date field. If there is a date present for "Project End Date" then everything works fine. However, if there is no date present then I am trying to update the other three date fields to null. I have tried numerous was to set the value to null and with each attempt I receive the error:

 

OpenApiOperationParameterTypeConversionFailed

The 'inputs.parameters' of workflow operation 'Update_item_copy' of type 'OpenApiConnection' is not valid. Error details: Input parameter 'item/FirstDraftDue' is required to be of type 'String/date'. The runtime value '""' to be converted doesn't have the expected format 'String/date'.
 
I cannot figure out why it is coming out as basically an empty string when I am specifically asking for null.

 

All the methods I've tried:

  • I have used the expression and simply put in null
  • I've initiated a variable and set it to null and then set the dynamic value to the variable
  • I have used if equals and if empty to set it to null
  • I have used coalesce and even imbedded it within an if equals

None of these have worked and the flow continues to convert the null expression to "". First screenshot is the overall flow, and the red box highlights the piece that is failing. The second screenshot is the update item fields where I am currently using the variable to set the value, but again, I've tried various expressions in place of the variable.

 

JPappy_0-1705610103319.png

 

JPappy_1-1705610155647.png

 

  • codigreen Profile Picture
    codigreen 3 on at
    Re: Flow Converting Null to Empty String

    I had the same symptoms as you did. After switching to the classic designer, I could run the flow perfectly. All I did was switching and saving again.

  • JPappy Profile Picture
    JPappy 4 on at
    Re: Flow Converting Null to Empty String

    Hi @v-jefferni,

     

    It does not appear that it had anything to do with the modern vs. classic. It just seemed to start working, even in the modern view.

  • v-jefferni Profile Picture
    v-jefferni on at
    Re: Flow Converting Null to Empty String

    Hi @JPappy ,

     

    If you have accidentally switched to classic designer, modern designer may be the problem.

     

    Best regards

  • JPappy Profile Picture
    JPappy 4 on at
    Re: Flow Converting Null to Empty String

    Hi @v-jefferni, thanks for the reply! I tried that as well, figuring that would be the easiest solution and why I created the secondary conditional branch. That too was not working. HOWEVER, suddenly it is all working now, including using if(equals(coalesce(, which I had tried multiple times already to no success. I am now convinced there had to have been some kind of bug going on that was unnecessarily causing it to fail. 

  • v-jefferni Profile Picture
    v-jefferni on at
    Re: Flow Converting Null to Empty String

    Hi @JPappy ,

     

    I'm able to update Date time field with null value, but it's in classic designer not sure if it's related.

    vjefferni_0-1705636504457.png

    vjefferni_1-1705636552811.png

     

    Best regards,

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