https://github.com/jonashackt/dmndemo
DMN-Decision Table example with camunda dmn-engine
https://github.com/jonashackt/dmndemo
Last synced: about 1 year ago
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DMN-Decision Table example with camunda dmn-engine
- Host: GitHub
- URL: https://github.com/jonashackt/dmndemo
- Owner: jonashackt
- Created: 2015-07-06T08:25:00.000Z (almost 11 years ago)
- Default Branch: master
- Last Pushed: 2019-05-24T11:45:14.000Z (about 7 years ago)
- Last Synced: 2025-02-13T14:24:29.789Z (over 1 year ago)
- Language: Java
- Size: 27.3 KB
- Stars: 1
- Watchers: 4
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# dmndemo
[](https://travis-ci.org/jonashackt/dmndemo)
[](https://coveralls.io/r/jonashackt/dmndemo)
Sample Project showing Usage of [camunda DMN engine] working with DMN-compliant Decision Tables.
It uses [SpringBoot](http://projects.spring.io/spring-boot/) as a basis and performs a Test on a predefined decision-Table (for modelling see the [DMN Modeler](https://camunda.org/dmn/tool/) ).
### Howto
Just clone, mvn clean eclipse:eclipse and run the Test - e.g. in your IDE, to see what´s going on.
### Call Java-Method from within DMN-Table to execute more complex logic
In some cases the build in Expression Language [FEEL](https://camunda.org/dmn/tutorial/#feel) isn´t sufficient to check more complex Logic. In this case, it´s nice to simply call a Java-Method from within your Decision-Table via the Groovy Expression Language, which is supported in camunda´s [DMN Expressions](https://docs.camunda.org/manual/7.4/user-guide/dmn-engine/expressions-and-scripts/).
For that you need to add Groovy to your Classpath (I omit the version here, because SpringBoot ships Groovy already):
```
org.codehaus.groovy
groovy-all
```
In your Decisiontable you need to define a simple column with a name (in this example it´s "zip") you´ll use later when calling the DMN-Engine and a appropriate Datatype - e.g. String.
Then add your Custom-Logic within a Java-Class´ static method (that returns a boolean) to the Project,
import the Class in Groovy and call the Method - e.g. like that:
```
import de.jonashackt.dmndemo.PostalcodeChecker
return PostalcodeChecker.isValidPostalcode(cellInput);
```
Note the correct import of your Class and also note the usage of "cellInput" - which contains the Value to check, passed into the DMN-Engine along with the other Variables.
**A Note for users of DMN-Modeler**: If you use the camunda [DMN-Modeler](https://camunda.org/dmn/tool/) (which is a good idea :) ): the last stable Version (0.3.x) removed the Script-Call at the moment - this didn´t happen with the current [Nightly-Build](https://camunda.org/release/camunda-modeler/nightly/) any more.
You need to resist to use the camunda-Modeler feature to insert a "Script" into a table column:
This will execute the script all the time the decisiontable is evaluated.
As long as this [feature](https://github.com/bpmn-io/dmn-js/issues/20) isn´t shipped, there are 2 Options:
**Option 1:** You have to open the dmn.xml in a texteditor and alter a rule yourself - e.g. like this:
```
```
**Option 2:** You insert the groovy-Script via the camunda-Modeler and open the XML after saving it up, to add the expressionlanguage-Definition to the right rule:
```
expressionLanguage="Groovy"
```
Now if you run a Test, which fill´s the VariableMap correctly, it should evaluate your Rule and call the Java-Method with your Custom logic:
```
// Should be ok
VariableMap variables = Variables
.putValue("state", "France")
.putValue("product", "RedCar")
.putValue("zip", "99425");
DmnDecisionTableResult result = dmnEngine.evaluateDecisionTable(states2ship, variables);
assertNotNull(result.getSingleResult());
assertEquals("notok", result.getSingleResult().getEntryMap().get("result"));
assertEquals("sorry, no shipment possible", result.getSingleResult().getEntryMap().get("reason"));
```
To see all this in Action, simply run [DmndemoApplicationTests.java](https://github.com/jonashackt/dmndemo/blob/master/src/test/java/de/jonashackt/dmndemo/DmndemoApplicationTests.java).
[camunda DMN engine]:https://github.com/camunda/camunda-engine-dmn