Handling non-existant properties?

[howitzer1972]

Very new to Flow and hope I just missing something basic here. 

I designed a Flow to send an email notification to users with a list of items from a SharePoint library.

In the Select action I am selecting the fields from the Filter that I want to send but the issue is that if the column is blank in SharePoint.  The Flow fails with a message that the Property does not exist. The field I'm using is a Choice column with a blank default value.

I spent a couple days coming up with a solution that creates an array from the items, iterates through array and checks each item to see if the property exists.  Adds a default missing property and then updates the array with the information. It seems to work as I need, but just seems overly complicated for something as simple as checking the property exists and using a default value if it doesn't.

I tried a lot of different things based on other forum posts, web searches and the MS Flow documentation.  So far this is the only way I can get it to work.  I just wondering if I am missing something easy to handle this instead of adding so many additional actions to the flow.  I actually need to handle 5 fields that may be blank and this seems overly complicated.  It seems like there should be an @exists function or something like that to trap the error. Alternatively I suppose I could force the SharePoint library to not allow blanks but that is changing the functionality of the library that the end users are used to.

[v-yamao-msft · Accepted solution]

Hi @howitzer1972,

Yes, it is a default behavior for action Select, any blank value won’t be allowed for the value. All the columns must contain value when using action Select.

While we could use a function to return a blank value depends on the situation.

For the Choice column, please try the following code:

if(empty(item()?['Choice']?['Value']),' ',item()?['Choice']?['Value'])

I have made the following test and it works just fine.

In the Create HTML table, use the following code for each field.

Title: item()?['Title']

Choice: item()?['Choice']

In the Send email action, make sure select Yes for Is HTML field.

Best regards,
Mabel Mao

[howitzer1972]

Thank you, that worked. 

Power of a Question Mark!

I had tried the same approach but used various iterations of  item()?['Choice']?['Value'] but never tried using a ? between all of the terms.

[Lexn]

Having empty values in Select action caused issues so needed a way to use default value in case of empty. This solution worked for me!

Thank you @v-yamao-msft!!!

if(empty(item()?['Address']),'blank',item()?['Address'])

[LenC]

I guess this is a solution to Select's problem - using the 'if' conditional for source properties. Seems kind of tortured. I looked at other array activities such as "Create HTML Table". It has NO problem if one of the properties of the input array is missing. But Select the same input array fails pulling the same field out of a collection of SharePoint items returned by SharePoint GetItems().

I noticed that the Flow Expression Editor | Dynamic Properties references items with the syntax item()?['PropertyName'] or items('iterator name')?['PropertyName'] - including the question mark. In many Flow activities, the question mark is retained when the flow is saved. But in the Select activity, the question marks get removed after saving. Which you can see by peeking the code, or exiting and returning to the editor.

Why is Select different than most activities in this regard?

[3tsolutions]

I wrote a solution to handle missing properties of an object, if it helps

LINK

[kymramos]

Thanks for highlighting the use of '?'.

I ran into a similar issue and also got curious about the difference between an expression that has the '?' and one that has not. Sharing @Pstork1's explanation: Solved: Re: Use of Question Mark(?) in expressions - Power Platform Community (microsoft.com)