28 May 2020

Cannot match arguments error when using acesHttpOperation

You can send updates from inside the Design Automation server using the onProgress callback mechanism - see https://forge.autodesk.com/blog/communicate-servers-inside-design-automation
The way to do that is to print a message to the command line with !ACESAPI:acesHttpOperation() - see https://forge.autodesk.com/en/docs/design-automation/v3/developers_guide/callbacks/
Note: in case of Inventor AppBundle you can use the HttpOperation() utility method 

You have to make sure that all the parameters are set correctly, adhering to these rules:
- 1st argument can be any word
2nd and 3rd argument can be anything that isn't a comma ','
4th argument can either be json {...} or anything that isn't a comma ','
5th argument must start with a word or ':' or '\' or '%' followed by zero or one dots '.' followed by zero or more of anything

Here is the regex rule to help you with this: 


You can simply use an online editor like https://regex101.com/ to verify the string you are providing is correct - see above picture

If you're not following the rules and e.g. try to do this:

  "{ \"current-progress\": 30, \"step\": \"apply parameters\" }"

Then you'll run into "Error: API failed. Reason = Cannot match arguments.":

[05/28/2020 17:02:45]     InventorCoreConsole.exe Information: 0 : RunWithArguments called
[05/28/2020 17:02:45]     InventorCoreConsole.exe Information: 0 : !ACESAPI:acesHttpOperation(onProgress,"","",{ "current-progress": 30, "step": "apply parameters" },"")
[05/28/2020 17:02:45] !!!!This is an API callback => "    InventorCoreConsole.exe Information: 0 : !ACESAPI:acesHttpOperation(onProgress,"","",{ "current-progress": 30, "step": "apply parameters" },"")"
[05/28/2020 17:02:45] Start processing API request acesHttpOperation.
[05/28/2020 17:02:45] Error: API failed. Reason = Cannot match arguments.
[05/28/2020 17:02:45] Done processing API request with result: failed. Time spent 0.0008435 seconds.

The problem with the above code is that the 5th argument cannot be an empty string, and should be modified to e.g.:

  "{ \"current-progress\": 30, \"step\": \"apply parameters\" }"


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Adam Nagy

Follow @AdamTheNagy Adam Nagy joined Autodesk back in 2005 and has been providing programming support, consulting, training and evangelism to external developers. He started his career in Budapest, then worked in Prague for 3 years and now lives in South England, UK. At the moment focusing on Inventor and Fusion 360, plus cloud and mobile related technologies. Adam has a degree in Software Engineering and has...