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Failing to compare a string variable with null

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Posted on by RP-10041546-0

Hi guys, I have a condition to compare a variable that has an email address and a null value. If I enter the empty function, it still needs 'a condition' like 'is qual to' and a value...

the above shows like this in the code:

"type": "If",
  "expression": {
    "and": [
      {
        "not": {
          "equals": [
            "@empty(variables('strUserEmail'))",
            ""
          ]
        }
      }
    ]
  },

and if I compare the variable with null, it is always true....

How can I check the variable if its null?

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Michael E. Gernaey 53,969 Moderator on at

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Hi @RP-10041546-0

I would do this, where you replace myemail with your property

and then the false expression

Now if its NOT empty you get yes and if it is you get no

And if you want to specifically compare to null

you have to use the Expression null

Where as it looks like you Typed Null

if you want both (which Empty should work by itself)

If this helps you, please mark as such and maybe a like :-)

Thanks!!

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BB-18031745-0 125 on at

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Not sure if I understand the logic in your expression, but another thing to note is that an empty string ("") is not equal to null.

If you are simply trying to check if the variable has an email address or is empty, you may need to compare it to an empty string instead.

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ronaldwalcott 3,862 Moderator on at

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How did you initialize the variable? Are you sure that it is null?

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RP-10041546-0 4 on at

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Thanks all for your input. I created the following:

which like this in the "Code":

{

"equals": [

"@empty(item()?['System.AssignedTo'])",

"@true"

]

}

This is working fine now.

The field 'System.AssignedTo' is coming from Azure DevOPS and its empty when it has not been assigned.

I receoved input from another thread which is worth adding here:

Whenever a string variable is set to a null, Power Automate tries to convert it to an empty string and stores it as “” in the backend. This means the variable is no longer "Null", but it is "Empty". (Yes... this is the weird world of Power Automate).
Because of this, you need to use the null compare for dynamic field values (comparing them directly as opposed to assigning them to a variable and then comparing the variable) and empty comparison for string variable values .

Thanks to all

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