How do I configure the constraints for a Split node in Drools Flow to test the value of a process variable?
7:38 a.m.
I have a requirement for a simple rule flow containing a "status" process
variable; a work item sets the value of this variable via its Result
Mapping. Following the work item is an XOR Split node, which can go to one
of two following nodes, depending on the value of the status process
variable. The relevant sections from the rule flow definition, as
currently written, are as follows:
<header>
<variables>
<variable name="status" >
<type
name="org.drools.process.core.datatype.impl.type.StringDataType" />
</variable>
...
</variables>
</header>
<nodes>
...
<workItem id="4" name="Test work item" x="352"
y="52" width="80"
height="40" >
<work name="TestItem" >
</work>
<mapping type="out" from="status" to="status"
/>
</workItem>
...
<split id="9" name="Split" x="464" y="52"
width="80" height="40"
type="2" >
<constraints>
<constraint toNodeId="10" toType="DROOLS_DEFAULT"
name="error"
priority="1" type="code" dialect="java"
status.equals("error")</constraint>
<constraint toNodeId="8" toType="DROOLS_DEFAULT"
name="success"
priority="1" type="code" dialect="java"
status.equals("success")</constraint>
</constraints>
</split>
...
</nodes>
The Java code that implements the "TestItem" work item finishes with the
code:
Map<String, Object> results = new HashMap<String, Object>();
results.put("status", status); // Value of status can be
"success" or
"error"
ksession.getWorkItemManager().completeWorkItem(stepInstance.getWorkItemId(),
results);
When I execute this process, no matter what the value of the status result
returned by the work item, the node with ID 8 (the 'success' path) always
executes.
I hope it's clear what I'm trying to do (i.e. define a process variable,
sets its value using the result from a work item, and then test its value
in a Split node); can anyone help me out as to why it's not working?
(Incidentally, this is Drools v5.1M1.)
Many thanks,
Alan
10:33 a.m.
Alan,
Your code constraints should look something like:
return "error".equals(status);
Do you check for errors after loading a process? Basically, errors
should be detected when trying to parse the given process because the
constraints could not be compiled (at least, that happened when I tried
something similar).
KnowledgeBuilderErrors errors = kbuilder.getErrors();
if (errors.size() > 0) {
for (KnowledgeBuilderError error: errors) {
System.err.println(error);
}
throw new IllegalArgumentException("Could not parse knowledge.");
}
If you don't get any errors, could you sent me a self-contained example
that shows this issue, so I can figure out what's going on?
Thx,
Kris
Quoting Alan.Gairey(a)tessella.com:
I have a requirement for a simple rule flow containing a
"status"
process
variable; a work item sets the value of this variable via its Result
Mapping. Following the work item is an XOR Split node, which can go
to one
of two following nodes, depending on the value of the status process
variable. The relevant sections from the rule flow definition, as
currently written, are as follows:
<header>
<variables>
<variable name="status" >
<type
name="org.drools.process.core.datatype.impl.type.StringDataType" />
</variable>
...
</variables>
</header>
<nodes>
...
<workItem id="4" name="Test work item" x="352"
y="52" width="80"
height="40" >
<work name="TestItem" >
</work>
<mapping type="out" from="status" to="status"
/>
</workItem>
...
<split id="9" name="Split" x="464" y="52"
width="80" height="40"
type="2" >
<constraints>
<constraint toNodeId="10" toType="DROOLS_DEFAULT"
name="error"
priority="1" type="code" dialect="java"
>status.equals("error")</constraint>
<constraint toNodeId="8" toType="DROOLS_DEFAULT"
name="success"
priority="1" type="code" dialect="java"
>status.equals("success")</constraint>
</constraints>
</split>
...
</nodes>
The Java code that implements the "TestItem" work item finishes with
the
code:
Map<String, Object> results = new HashMap<String, Object>();
results.put("status", status); // Value of status can be
"success" or
"error"
ksession.getWorkItemManager().completeWorkItem(stepInstance.getWorkItemId(),
results);
When I execute this process, no matter what the value of the status
result
returned by the work item, the node with ID 8 (the 'success' path)
always
executes.
I hope it's clear what I'm trying to do (i.e. define a process
variable,
sets its value using the result from a work item, and then test its
value
in a Split node); can anyone help me out as to why it's not working?
(Incidentally, this is Drools v5.1M1.)
Many thanks,
Alan
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
3:20 a.m.
New subject: How do I configure the constraints for a Split node in Drools Flow to test the value of a process variable?
Kris,
Thanks for the fast response - the 'return' statement made all the
difference - it's working as expected now.
This was code from a simple unit test, so I wasn't initially checking
errors after loading the process. After adding the code you suggested, the
old process definition (i.e. without the return statement in the split
node constraints) failed to parse with the following error:
"This method must return a result of type Object"
- pretty obvious that a return statement was required. I'll be sure to
add the error checking code to all future tests. ;)
Thanks again for your help,
Alan
Kris Verlaenen <kris.verlaenen(a)cs.kuleuven.be>
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19/10/2009 16:43
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cc
Subject
Re: [rules-users] How do I configure the constraints for a Split node in
Drools Flow to test the value of a process variable?
Alan,
Your code constraints should look something like:
return "error".equals(status);
Do you check for errors after loading a process? Basically, errors
should be detected when trying to parse the given process because the
constraints could not be compiled (at least, that happened when I tried
something similar).
KnowledgeBuilderErrors errors = kbuilder.getErrors();
if (errors.size() > 0) {
for (KnowledgeBuilderError error: errors) {
System.err.println(error);
}
throw new IllegalArgumentException("Could not parse knowledge.");
}
If you don't get any errors, could you sent me a self-contained example
that shows this issue, so I can figure out what's going on?
Thx,
Kris
Quoting Alan.Gairey(a)tessella.com:
I have a requirement for a simple rule flow containing a
"status"
process
variable; a work item sets the value of this variable via its Result
Mapping. Following the work item is an XOR Split node, which can go
to one
of two following nodes, depending on the value of the status process
variable. The relevant sections from the rule flow definition, as
currently written, are as follows:
<header>
<variables>
<variable name="status" >
<type
name="org.drools.process.core.datatype.impl.type.StringDataType" />
</variable>
...
</variables>
</header>
<nodes>
...
<workItem id="4" name="Test work item" x="352"
y="52" width="80"
height="40" >
<work name="TestItem" >
</work>
<mapping type="out" from="status" to="status"
/>
</workItem>
...
<split id="9" name="Split" x="464" y="52"
width="80" height="40"
type="2" >
<constraints>
<constraint toNodeId="10" toType="DROOLS_DEFAULT"
name="error"
priority="1" type="code" dialect="java"
>status.equals("error")</constraint>
<constraint toNodeId="8" toType="DROOLS_DEFAULT"
name="success"
priority="1" type="code" dialect="java"
>status.equals("success")</constraint>
</constraints>
</split>
...
</nodes>
The Java code that implements the "TestItem" work item finishes with
the
code:
Map<String, Object> results = new HashMap<String, Object>();
results.put("status", status); // Value of status can be
"success" or
"error"
ksession.getWorkItemManager().completeWorkItem(stepInstance.getWorkItemId(),
results);
When I execute this process, no matter what the value of the status
result
returned by the work item, the node with ID 8 (the 'success' path)
always
executes.
I hope it's clear what I'm trying to do (i.e. define a process
variable,
sets its value using the result from a work item, and then test its
value
in a Split node); can anyone help me out as to why it's not working?
(Incidentally, this is Drools v5.1M1.)
Many thanks,
Alan
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
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Alan.Gairey＠tessella.com -
Kris Verlaenen