Test for Empty Array?

[ericonline]

Hello. I'm using the O365Users connector to look up employees in Active Directory. If an employee is NOT in AD, the response is Body: []. 

I cannot figure out how to determine if "[]" is true using a Condition.

I've tried 10 different Expressions including:

• empty(array('Search_for_users'))
• array('Search_for_users', '[]')
• array('Search_for_users', '/[/]')
• []
• '[]'
• '/[/]'
• string('[]')
• and every other iteration I could think of!

Can anyone assist?

Thank you

[ericonline · Accepted solution]

Jeez, this is crazy. Finally got this after spending MANY hours trying every variation...

Apparently taking the Body from Search_for_users and comparing it to an empty() array...

Is NOT the same as adding empty() alone...

This is the type of thing that make learning Flow VERY DIFFICULT.

[Munters]

I agree! I ran into the same problem.

I ended up convering the body array to a string and checking if the length was less or eq to 2 ([]):

length(string(body('Search_for_users')))

Not very elegant but it works for me.

[Anonymous]

gosh I wish I found this thread earlier... think I've gone through every iteration other than that one

[ericonline]

@RezaDorrani also showed me another method for this type of check. Might be of use to folks...

empty(body('Search_for_users')) is equal to true

[FrankChen]

You don't need to convert to string. you can try use length(body('Search_for_users')) equal 0

[Anonymous]

Hello! And apologies for hijacking this thread slightly but I have a question on the back of it.

You / OP has said "If an employee is NOT in AD, the response is Body: []"

However I'm finding that the body for one particular flow / user is [] even though they ARE in AD. And I'm wondering if anyone knows why this might be? I can see the user has a handful of empty data fields within their AD user object (Job Title, Department etc) so my go-to thought is that they are being treated as a non-entity because one of these fields is empty, but I'm not sure if that's definitely the case, or which field if it is the case.

[LadyAda]

Thank u!, it worked perfectly.

[Munters]

You are correct. Your solution is even better. Thanks. 

[Anonymous]

Hi,

This seems like bug as workaround what I did is create another variable as empty array used that to compare with out value which in our case is body i believe.

[Civart]

Heey,

I know this is an old issue, but I write this down anyway for people new to this subject.

This issue has nothing to do with Flow really and it isn't a bug. The logic you try to apply is incorrect and Flows is correct. The Condition action should have a Boolean (true or false) as input. The function empty(variable x) returns 'true' when variable x is empty or 'false' if it is not empty. In your example you want to check if 'Search_for_users' is empty, but you don’t. You check if the value of ‘Search_for_users’ is equal to the return value of the empty(variable x) function.

For example: ‘Search_for_users’ doesn’t have a value (this means it’s value isn’t true or false, but empty). The function empty(‘Search_for_users’) returns true because ‘Search_for_users’ is empty. So what you are asking in your first example is: Is the body of ‘Search_for_users’ equal to the return value of empty('Search_for_users)? NO it isn’t. ‘The body for Search_for_users’ isn’t true but empty. In other words: Is null equal to true --> No it is not.

Your second example DOES work because empty(‘Search_for_users’) returns true to the Condition action. In your first example you compare the body value of ‘Search_for_users’ with the return value of the empty() function, which in turn returns false to the Condition action.

So your condition should be: empty(‘Search_for_users’) is equal to true.

[diavoloplanas]

hi im form mexico im going to try use my best

im trying to put this on my flow empty(body('buscar_usuarios_(V2)'))  but always say true i try to use @ but in my flow say that this ewxpression its grong

i dont now what to do now 

i try all the answers in this 

what im doing wrong =(

my result ist not true always its false

[diavoloplanas]

i have this error message

"La función de lenguaje de plantilla "length" espera que su parámetro sea una matriz o una cadena. El valor que se ha proporcionado es de tipo "Object"

[Civart]

Hello diavoloplanas,

The error La función de lenguaje de plantilla "length" espera que su parámetro sea una matriz o una cadena. El valor que se ha proporcionado es de tipo "Object" is saying that you gave an object to the length function. However, the length function can only have a string or an array as input. This is logical because the function should be able to count something.

String

A string exists out of characters. The string "hello" has 5 characters, so the length function will return 5.

Array

An array exists out of elements. The length function counts the number of elements, for example:

["Green", "Blue", "Red"] <-- this array has 3 elements: green, blue and red. So the function returns 3. 

Object

For an object there is no way the function understands what the length is because an object can exist out of anything. An object can have multiple properties. For example:

{

"Haircolor": "Brown",

"Eyecolor": "Blue",

"Height": 182,

"Age": 33,

"Brothers": ["Jason", "Alex"]

}

The properties of this object are: haircolor, eyecolor, height, age and brothers. The length function can count the number of characters in the property haircolor or eyecolor and the number of elements in the property brothers. So you should provide the length-function one of these properties and not the object itself.

Empty() function

For the empty() function you can provide an object as a parameter. If the object doesn't have anything (null) the function will return true. If it's not empty (not null) then it will return false. If the empty function tells you that body(buscar_usuarios_(V2)) is empty than the body properly is empty.

What to do?

When you run the flow, you can see the output of the Buscar Usuarios (V2) action. Can you please tell me what is in there? That way I might be able to help you.

Kind regards,

Civ

[dangthis]

I also used length to solve this issue. But, I want to call out that when used on an array, it counts the objects in the array vs the characters. I tested to confirm this by initializing an integer and setting its value to the same function, length(body('Filter_array'))

Which yielded this result

At face value, we see that there is more than 4 characters there. Loading the raw output from the filter array into a JSON viewer, we see there are 4 objects

So to simplify the Flow, you dont have to convert the array to a string, just set your condition to greater than 0

[Jfranz]

Just adding my experience to this since even with all the above awesome information I still struggled. Below is my flow, I have a Get Items that is looking for a specific item in a list. When it doesn't find anything it returns an empty array. So for testing purposes I set my variable to be an array with the results of the filter - that checked out so I created a compose that will return a value of true or false if the array is empty. The function in the compose is 

empty(variables('FilteredArray')) FILTEREDARRAY is the name of my variable. Then in my condition I had to set the outcome of the compose to equal the function false - if I just typed in false it would not work. I think for a cleaner flow I could get rid of the array variable and just achieve this in the condition but it JUST wouldn't go.

my workaround

[allan_t]

I had a similar issue.  I also recommend checking the "Configure Run After" setting of your Condition Control connector.  In my scenario, the default was for the condition control to only run if the Search for User previous step was successful.   If you want the Condition control to run after Search returns a "user not found", you need to change the Configure Run After setting.   

The default was to only run after success.  I selected all options, then it ran as expected.  

[wcavarra]

Thank you for taking the time to submit your solution, it was very helpful.