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| | | Supreme Being
Group: Forum Members
Last Login: Sunday, August 22, 2010
Posts: 11, Visits: 43 |
| I'd like to use decision action based on the existence of a Workflow instance variable. If I add a rule like "Variable.MyVariableName Contains Data", I get an error that looks like:
**** Error while executing GetProcessedValue : System.Reflection.TargetInvocationException:
System.NullReferenceException:
Looking at the generated code, it uses:
_context.Variables["MyVariableName"].Value
which would cause a NullReferenceException if _context.Variables["MyVariableName"] is null. Is there another way to determine if MyVariableName is null?
Thanks |
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| | | Senior Member
Group: Forum Members
Last Login: Friday, January 16, 2009
Posts: 8, Visits: 21 |
| | Hi Tonyyng, You can use Expression Editor in Decision action to determine whether the variable (MyVariableName) is null or not. Use the below sample code in Decision action's Expression editor. Find attached the document (DecisionAction.doc) as well as the workflow xml (NullVariable.zip) for your referecce. (Variable.MyVar == null) ? true: false ReturnType+= Sysetm.Boolean Let us know the status after performing this. Regards, Anil
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| | | Supreme Being
Group: Forum Members
Last Login: Sunday, August 22, 2010
Posts: 11, Visits: 43 |
| Thanks. That worked fine.
The expression can be simplified from:
(Variable.MyVariable == null) ? true:false
to
Variable.MyVariable == null |
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| | | Supreme Being
Group: Forum Members
Last Login: Monday, November 21, 2011
Posts: 11, Visits: 66 |
| | Hi I'd like to raise an issue with this scenario,I have tried this solution in BPM.NET 2006 and it works fine, however, when using a task based variable, it does not work, e.g. (Variable.^UI-SingleTaskRespondingUser==null)?true:false On clicking OK, the following error appears: | c:\WINDOWS\Temp\_l173fja.0.cs(11,9) : error CS1525: Invalid expression term '==' | | | | c:\WINDOWS\Temp\_l173fja.0.cs(11,11) : error CS1026: ) expected | | | | c:\WINDOWS\Temp\_l173fja.0.cs(11,15) : error CS1002: ; expected | | | | c:\WINDOWS\Temp\_l173fja.0.cs(11,15) : error CS1525: Invalid expression term ')' |
Code generated is: using System;
using System.Text;
using Workflow.NET;
namespace Samplenamespacec161bc3071584a52b349f3e4c14100fa
{
public class Sampleb508fd62ffdd42d397030bdaa6fe35df
{
public object SampleMethodbff44cf2a4b7434db7c9960282fd0b41(Workflow.NET.Engine.Context _context)
{
return (==null)?true:false ;
}
}
}
In the code it is dropping the variable, should this work? Thanks Jon |
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| | | Supreme Being
Group: Forum Members
Last Login: Thursday, February 10, 2011
Posts: 28, Visits: 47 |
| Hi Jon, You may try using the individual property of the respective variable as mentioned below Variables.^CandidateApprovalRespondingUser.UserName==null?true:false This should work. Regards Saravanan |
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| | | Supreme Being
Group: Forum Members
Last Login: Monday, November 21, 2011
Posts: 11, Visits: 66 |
| Hi Saravanan Thanks for your response, this allowed me to set up the decision task, however, the workflow always finishes at the decision task with no output, so if I check for Null and if it is the output should be NULL, else NOTNULL, but neither output is generated, it just stops. The error logged is as below. Cheers Jon i - @#@Date - 14:58:21.984@#@Module - C:\WINDOWS\assembly\GAC_MSIL\Workflow.NET.NET2\3.0.0.0__00d117614105018c\Workflow.NET.NET2.dll@#@FileName - Context.cs@#@_MachineName - gblontvm02, Process - WFEngine.NET2@#@Message - Completed - Action Start for ExecutionID=67 ExecutionDetailsID=562 Exiting with Output=@#@
i - @#@Date - 14:58:22.0@#@Module - C:\WINDOWS\assembly\GAC_MSIL\Workflow.NET.NET2\3.0.0.0__00d117614105018c\Workflow.NET.NET2.dll@#@_MachineName - gblontvm02, Process - WFEngine.NET2@#@Message - **** Error while executing GetProcessedValue : System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at Workflow.NET.DynamicCode.WorkflowDecisione64b7ef0eb7e41a0a9197eca9677d610.Methodb2390330c40741c5b63e750d0178cad0(Context _context)
at Workflow.NET.DynamicCode.WorkflowDecisione64b7ef0eb7e41a0a9197eca9677d610.GetProcessedValue(Context _context)
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Workflow.NET.PropertyTypes.PropertyDecision.GetProcessedValue(Context _context)@#@
i - @#@Date - 14:58:22.0@#@Module - C:\WINDOWS\TEMP\Skelta2006Temp\WorkflowElements\Faraday\ShadowTempFaraday\assembly\dl3\b36a7c14\00c4b3cc_fb9fc801\Workflow.NET.ActionHandler.NET2.DLL@#@FileName - Context.cs@#@_MachineName - gblontvm02, Process - WFEngine.NET2@#@Message - Output after evaluating the expression for action Decision1 : ExecutionId:67 ExecutionDetailsId:563@#@
i - @#@Date - 14:58:22.0@#@Module - C:\WINDOWS\TEMP\Skelta2006Temp\WorkflowElements\Faraday\ShadowTempFaraday\assembly\dl3\b36a7c14\00c4b3cc_fb9fc801\Workflow.NET.ActionHandler.NET2.DLL@#@FileName - Context.cs@#@_MachineName - gblontvm02, Process - WFEngine.NET2@#@Message - Persist Actioin log Messages Completed. ExecutionId:67 ExecutionDetailsId:563@#@ |
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| | | Supreme Being
Group: Forum Members
Last Login: Thursday, February 10, 2011
Posts: 28, Visits: 47 |
| Hi Jon, You might get the exception "Error while executing GetProcessedValue" if the variable which you have used within the workflow contains NULL and trying to compare/route the decision activity. If the variable contains NULL there will not be any output from the decision activity. Ensure that variable has an appropriate value so that the workflow proceeds further with the next step following the decision activity and also executes successfully. |
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| | | Supreme Being
Group: Forum Members
Last Login: Monday, November 21, 2011
Posts: 11, Visits: 66 |
| | Hi Saravanan But this was the point of the expression, to check whether the Variable is Null. I cannot set the value of this to a default value as it is a derived variable associated with the Task completion, i.e. one of your ^ variables, which you cannot populate with a SetVariable action. Is there no way of checking this within workflow, without writing code? Cheers Jon |
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| | | Supreme Being
Group: Forum Members
Last Login: Yesterday @ 9:21 PM
Posts: 17, Visits: 42 |
| | If the variable contains NULL , Decision Activity does not provide any output,there is no option to check this in the workflow. However, this is taken care in BPM.NET 2009. -Suman.
csn |
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| | | Supreme Being
Group: Forum Members
Last Login: Monday, November 21, 2011
Posts: 11, Visits: 66 |
| | Thanks Suman, I will have to deal with this another way. Cheers Jon |
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