openapi-generator/docs/debugging.md

id	title
debugging	Debugging

Templates

Sometimes, you may have issues with variables in your templates. As discussed in the templating docs, we offer a variety of system properties for inspecting the models bound to templates.

-DdebugOpenAPI

Prints out the JSON model of the OpenAPI Document, as seen by OpenAPI Generator

-DdebugModels

Prints out the JSON model passed to model templates

-DdebugOperations

Prints out the JSON model passed to operation (api) templates

-DdebugSupportingFiles

Prints out the JSON model passed to supporting files

One or more of these properties can be passed alongside other command line options:

openapi-generator generate -g go \
    -o out \
    -i petstore-minimal.yaml \
    -DdebugModels \
    -DdebugOperations

Or you can add these to your JAVA_OPTS environment variable (this applies to every invocation of the tool):

export JAVA_OPTS="${JAVA_OPTS} -DdebugModels -DdebugOperations"

NOTE: Globally available system options like these will apply to all invocations of the generator (CLI and plugins)

Runtime

When you're working with a custom generator, a new generator, or otherwise trying to understand the behavior of the toolset, you may need to attach a remote debugger in order to step through the code.

The steps are shown here for a specific version of the generator, but apply the same if you're working off master or a feature branch.

• Determine the version of openapi-generator you're using. For the CLI, this is:

  openapi-generator version
  

• Navigate to the openapi-generator source directory (see building docs for obtaining source code and brief introduction).
• Checkout the branch/tag for the target version. Branches are not prefixed, but tags are prefixed with a v. For instance if you're using version 3.3.0, you will execute:

  git checkout v3.3.0
  

• Open the project in your IDE.
• Setup your IDE for remote debugging. You'll want to define a port used for connecting the remote debugger. For this example, we'll use 5005. See external tutorials for IntelliJ and Eclipse
• Export the debug configuration, specifying suspend=y so you have time to attach a remote debugger. These are passed as Java system properties, either on command line or as part of the JAVA_OPTS environment variable. This will look like:

  export JAVA_OPTS="${JAVA_OPTS} -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005"
  

• Execute the generator with your desired options. You should see the application output only

  Listening for transport dt_socket at address: 5005
  

• Set breakpoints in code, and then attach your remote debugger from your IDE (see above). The generator will automatically unblock once the remote debugger is attached. You can now step through the code.

Logs

You can try to enable debugging log with -Dlog.level=debug option to the JAVA_OPTS environment variable to see more information:

export JAVA_OPTS="${JAVA_OPTS} -Dlog.level=debug"

Set the option then DEBUG logs are printed out:

openapi-generator generate -g go ...

...
...
[main] DEBUG o.o.codegen.DefaultCodegen - debugging fromProperty for files : class Schema {
    type: null
    format: null
    $ref: #/components/schemas/File
...
...