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Passing parameter that can be Null to Flow

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Posted on by linx9

Hello.

I have build a Power Automate flow that takes inputs from PowerApps. It has a few mandatory parameters and an optional String parameter ("varPergunta6").

The thing is, in the way my app currently works, the value sent in "varPergunta6" may sometimes be Null, because it stems from a non-mandatory question in a formulary. I thought making the field optional would allow that, but apparently not, because I'm getting the following error:

This is the code I'm using to call the Flow:

submitRespostaTreinamentoV2.Run(
 tempCodResposta,
 tempCodVisitaOS,
 tempPergunta1,
 tempPergunta2,
 tempPergunta3,
 tempPergunta4,
 tempPergunta5,
 {text_4: tempPergunta6}
);

Sending an empty String "" instead of the Null value would not help me because the empty String will be represented differently in the database. And also because that would not be possible to do in other cases where the parameter is an Integer instead of a String

Is there any workaround for this?

Thanks in advance.

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Building Power Apps

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AhmedSalih 6,678 Moderator on at

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Hello, @linx9 , You can use an expression like the one below in your Insert Row action for this Field:
if( empty(varPergunta6), null, varPergunta6 )

Regards,

Ahmed

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linx9 62 on at

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Hi @AhmedSalih

Thanks for the input. That unfortunately does not solve the problem.

The error I get when calling the Flow in PowerApps is happening before the Flow even gets executed, so the problem is not coming from things inside the Actions. The error comes from something in the interface between PowerApps and Power Automate that does not allow me to even send a Null parameter to the Flow.

The actions inside the flow are working just fine because I tested them manually before trying to call the Flow from PowerApps

Best regards

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v-peijunz-msft Microsoft Employee on at

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Hi @linx9,

Maybe you could try to pass the blank string from Power Apps to flow instead of sending a null parameter.
Based on your description, I have made a simple test for your reference.
1. I use a SharePoint list called Ignoreblank as my data source. The Initiative has no value in the first record.
2. In Power Apps, insert a button and write the formula in its OnSelect property as follows:
FlowInApp.Run(If(IsBlank(First(DataSource).ColumnName),"",First(DataSource).ColumnName), First(DataSource).ColumnName))
3. In Power Automate: If there is a blank in field, then use the null value.
if(equals(length(triggerBody()['text']), 0), null, triggerBody()['text'])
Here is my flow:

Best regards,
Sylvia

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linx9 62 on at

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Hi @v-peijunz-msft

Thanks for the input. Unfortunately using an empty String is not a good solution for me because that won't work for Integer and Boolean parameters.

However, I have a found a working solution in the meanwhile. I will post it here in case anyone end up facing the same problem in the future.

I created an "Optional" parameter of the type String in the inputs from PowerApps. This argument will contain all the optional parameters I would like to use in a JSON format.

This parameter is then parsed by a "Parse JSON" action:

The results from the Parse JSON can then be passed to SQL by using the coalesce function, which prevents the "Insert row" block from throwing errors when the Optional argument is null: coalesce(body('Parse_JSON')?['Pergunta3'])

I am using the following code when calling the flow from PowerApps:
ForAll(ModificacoesRespostasAcompanhamento, updateRespostaAcompanhamentoV4.Run( tempCodResposta, tempCodVisitaOS, tempPergunta1, tempPergunta2, JSON({ Pergunta3: tempPergunta3, Pergunta4: tempPergunta4, Pergunta5: tempPergunta5, Pergunta6: tempPergunta6, Pergunta7: tempPergunta7, Pergunta8: tempPergunta8 }) ) );

Best regards

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WO-23071515-0 on at

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Thank you, this is brilliant and you're a life saver

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