# How to generate an entity class from an OPT template?

**Category:** [Platform](https://discourse.openehr.org/c/platform-implem/7)
**Created:** 2024-09-06 01:57 UTC
**Views:** 91
**Replies:** 4
**URL:** https://discourse.openehr.org/t/how-to-generate-an-entity-class-from-an-opt-template/5665

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## Post #1 by @linforest

How to use the generator to generate an entity class from an OPT template?

```
 java  -jar generator-version.jar
 -h               show help
 -opt <arg>       path to opt file
 -out <arg>       path to output directory
 -package <arg>   package name
 -config <arg>    optional Path to config file
```
[GitHub: Usage](https://github.com/ehrbase/openEHR_SDK#usage)

When trying to do this in the syntax above, I got an error message:

```
Error: Failed to initialize the Main Class org.ehrbase.openehr.sdk.generator.ClassGeneratorRunner
Reason: java.lang.NoClassDefFoundError: org/apache/commons/cli/ParseException
```

Thanks.

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## Post #2 by @vidi42

@linforest are you using the jar downloaded from maven central? 
Can you try building the jar from the source code? Just clone the [openEHR SDK](https://github.com/ehrbase/openEHR_SDK), do a `mvn clean install` of the project and then try with the  `openEHR_SDK\generator\target\generator-2.17.0.jar`.

Not sure why it's not working with the jar from maven central, or if it's supposed to work directly from there.

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## Post #3 by @stefanspiska

If you look at https://github.com/ehrbase/openEHR_SDK/blob/develop/generator/pom.xml

During build it copies the dependencies to /lib and takes them from there.
So you seam to be missing the java dependencies

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## Post #4 by @linforest

Yes, it's from maven central.  As your suggested, I will try a locally-built copy.  Thanks.

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## Post #5 by @linforest

Your guess is likely right because the ehrbsse jars are limited to client, generator and their dependencies.  Thanks.

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**Canonical:** https://discourse.openehr.org/t/how-to-generate-an-entity-class-from-an-opt-template/5665
**Original content:** https://discourse.openehr.org/t/how-to-generate-an-entity-class-from-an-opt-template/5665