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Determine if string is an object

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Posted on by tekhnik

I am using an API that sometimes responds with a body of type string, and other times with a body object with some properties. I am first trying to determine which one was returned. If it is a string, I craft an object to return to the parent script.

My thought was to try to treat the value as an object and handle failures. e.g. this Set Variable action is set to

json( triggerBody()?['text'] )

However, the entire flow is considered as failed even though the error is handled

I've also tried with Compose to see if it was the type of action - same issue. I've also tried to generate failures with alternate expressions to see if they were handled differently. e.g.

addProperty( triggerBody()?['text'], 'X', 1 )

However, they all end up making the entire flow get flagged as a failure.

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v-xiaochen-msft Microsoft Employee on at

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Hi @tekhnik ,

Please try this

Best Regards,

Wearsky
Nived_Nambiar 18,138 Super User 2026 Season 1 on at

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Hi @tekhnik

I think you have set the api either to give response in format or application/json or text/html which causes its response to be in JSON or HTML .

To identify whether it is json or html string. I would recommend these two conditons

to check whether it is json string use following expression

startsWith(string(triggerBody()?['text']),'{')

to check whether it starts with HTML

startsWith(string(triggerBody()?['text']),'<html>')

When designed in flow - you can try like this

Hope it helps !

Thanks & Regards,
Nived N 🚀

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tekhnik on at

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I think you have set the api either to give response in format or application/json or text/html which causes its response to be in JSON or HTML .
Actually I have not done so. The API is always called with header Accept : application/json. It simply returns both simple strings and objects.

I cannot rely on that same API to always return specific tags, or NOT to return simple strings that begin with a curly brace. That is why I want a more generic method to check if a string can be cast as an object.

The issue I am trying to solve is that the workflow is marked as failed when I do so. Sorry if the title did not make that clear.
tekhnik on at

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Yes, that did it Wearsky! @v-xiaochen-msft

So that I can understand, can you explain or point me to documentation regarding overall flow status?

I assumed that if a parallel branch handled an error, it would not propagate down. In other words, if Compose2 in your flow was green, the flow should be green. Is the 'override' via Terminate necessary if any failures are encountered?
Chriddle 8,729 Super User 2026 Season 2 on at

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Probably the easiest and cleanest way to handle this is to check the status code in the response header..