We have created plug-in to write custom function in appian called as fn!mydataap

sridharj over 9 years ago

We have created plug-in to write custom function in appian called as fn!mydataappend and it accepts input param as Emplyee (CDT). After we deployed into appin we are able to see the custom function but when we call the function in appian we are getting below error. Could you please suggest what is the reason for that and solution.

Caused by: com.appiancorp.suiteapi.common.exceptions.AppianException: Unable to find a required instance of Employee. (APNX-1-4158-006)
          at com.appiancorp.process.expression.CustomFunction.evaluate(CustomFunction.java:597)
          at com.appiancorp.process.expression.CustomFunction.evalDynamic(CustomFunction.java:197)
          at com.appiancorp.process.expression.CustomFunction.eval0(CustomFunction.java:188)
          at com.appiancorp.core.expr.Evaluable.eval(Evaluable.java:213)
          at com.appiancorp.process.expression.ExpressionEvaluator.evaluate(ExpressionEvaluator.java:295)
          at com.appiancorp.core.expr.AppianScriptContextTop.evalExternalFunction(Appi...

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0 sridharj over 9 years ago

...anScriptContextTop.java:428)
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0 rawich over 9 years ago

Hi Sridhar, you might want to share your SAIL code invoking this function. It looks like the error happened just right before your code get executed. The issue is probably with how you pass the Employee CDT to the function.
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0 rishub356 over 9 years ago

with(
local!employeeData: {
firstName: "A",
middleName: "B",
lastName: "V"
},
fn!mydataappend(
local!employeeData
)
)
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0 rishub356 over 9 years ago

Hey rawichp236, Please find the sail code above. Thanks.
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0 rawich over 9 years ago

Two main things here:

1) You have to create your customer function as Writer function:
forum.appian.com/.../Custom_Function_Plug-ins.html
The first sentence in the section of document will tell you that a normal function should not modify data, because expression evaluation can happen multiple times, and you have no absolute control of how often, and when.
Once you created the function plug-in as Writer function, then you'll make a call to this function from within a bind(), which is within a load() functions.

2) The error you received was because your function got evaluated before the emplyeeData is properly defined. It's hard to tell, and we have no control of which part of with() function got evaluated first. But once you modify your function to be a Writer function, and do the call via a bind that tie to a user action (such as button clicked), then you won't have this issue.
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0 rawich over 9 years ago

I meant to say,
1) You have to create your custom function as a Writer function...
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0 rishub356 over 9 years ago

Thx Rawichp
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