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Custom Connector - Invalid expression for Parameter

I'm trying to create a custom connector that will call a webAPI method (CalculateRollupField). I'm following these steps:

https://www.powerappsguy.com/blog/Use-Power-Automate-Flows-to-Calculate-Rollup-Fields/

 

Everything works fine and the testing, but when I use it in a flow it gives this error "Fix invalid expression(s) for the input parameter(s) of operation 'CalculateRollupField'"

 

I tried changing the parameters to required, or pass the parameter with static text but no use.

 
5 REPLIES 5
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Community Support
Community Support

Re: Custom Connector - Invalid expression for Parameter

Hi @Eno ,

Could you please share a bit more about the "Fix invalid expression(s) for the input parameter(s) of operation 'CalculateRollupField'" error within your flow?

Do you mean that the custom connector work well when you test your custom connector?

 

Based on the blog that you mentioned, I could not find any configuration issue in your custom connector. According to the issue that you mentioned, I think this issue may be related to the value you typed within the @target field in your custom connector action within your flow.

 

When you type the following value:

{'@odata.id':'[your_entity]([your_recordid])'}

within the @target field in your custom connector action within your flow directly, it would be recognized as a object value rather than a Text string value. As an fixed solution, you could consider add a "Initialize variable" action before your custom connector action to store the @target field text value as below:

4.JPG

please consider take a try with above solution, then check if the issue is solved.

 

Best regards, 

Community Support Team _ Kris Dai
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
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New Member

Re: Custom Connector - Invalid expression for Parameter

Hi Kris,

Thanks for the reply.

Testing the connector from test tab works fine. And I've already tried using a variable and using compose action and both didn't work.

In addition, we found that the custom connector works if the flow is created in "My Flows". My flow is created inside an unmanaged solution, and even when I created the custom connector inside the solution it didn't work.

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Community Support
Community Support

Re: Custom Connector - Invalid expression for Parameter

Hi @Eno ,

Do you create your flow inside a Solution?

 

Aha, if you created your flow inside a Solution, I think your issue is related to it. Currently, there are some known limits with the Solutions, please refer to the following article:

https://docs.microsoft.com/en-us/powerapps/maker/common-data-service/solutions-overview#known-limita...

 

Currently, the custom connector created outside the Solution could not work inside a solution. Please consider use your custom connector outside the solution to fix this issue.

 

If you still want to use the custom connector inside your unmanaged solution, please consider re-create your custom connector in your solution as below:

1.JPG

then try your custom connector in canvas app inside the solution, check if the issue is solved.

 

Note: There are also some unknown issue with custom connector inside Solution, as a better solution, please use your custom connector outside a solution.

 

Best regards,

Community Support Team _ Kris Dai
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
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Regular Visitor

Re: Custom Connector - Invalid expression for Parameter

I'm experiencing exact same issue. Testing works but Flow shows error in parameter - invalid expression.

Tried:

  • building inside and outside of solution
  • building from app and outside app
  • using variables or compose to pre-create string
  • changing the parameter to lose the '@' symbol to not confuse with expression/dynamic parameter
  • changed the format of the parameter to byte ext.

Nothing appears to be working. It's annoying that unable to update roll-ups before executing next step of flow.

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New Member

Re: Custom Connector - Invalid expression for Parameter

I also having the same issues as described by the OP - following the same blog post (powerappsguy) - Also tried everything Nickes had mentioned - plus :

 

  • using @ as the escape sequence - (it is mentioned as an issue in LogicApps) 
  • replacing @ with %40

 

After much experimentation - I can now say that the issue is infact with the name of the input fields - @Target and @Fieldname

 

If you redefine the query to remove the @ symbol, you can see that the validation is successful. The issue now is that API does not recognise the parameters without the @ symbol. 

 

I have logged this as a case with MS, and they accept the issue.  Waiting for response.  For now I would suggest building a http action with manually constructed URL will provide a work around.

 

 

 

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