[BUG][Java] Java generator does not generate a model class for a schema named 'File'

[daiscog]

When an api.yml file contains a type definition called 'File' no model class is generated by the Java/spring generator for that type.

openapi-generator version

4.2.2

Details

The api.yaml file defines a type called File and an endpoint that returns a wrapper object containing a field of this type.

The generator is configured to use the package com.example.rest.model for generated model classes.

Expected behaviour:

• A class with the fully-qualified class name com.example.rest.model.File should be generated
• The generated wrapper class com.example.rest.model.FileWrapper should contain a field called file of type com.example.rest.model.File

Actual behaviour:

• No model class called com.example.rest.model.File is generated
• The files field of the generated wrapper class is of type java.io.File

Partial workaround:

The second issue (incorrect import type) can be worked around by explicitly adding the import-mapping File=com.example.rest.model.File to the configuration.

However, the class com.example.rest.model.File is still not generated.

Steps to reproduce

To reproduce, extract the attached oas-generator-file-bug.tar.gz file cd into the extracted project dir and run mvn clean generate-sources

Alternatively, the api.yaml file and a pom.xml configured to use the generator maven plugin can be seen here: https://gist.github.com/daiscog/71908355396370a6a4316d0adfeb6d31

[chadknight-wf]

@daiscog I ran into this as well. I've found that using the lowercase file name for the schema in your api.yaml results in the class being generated. Then you can set the import mapping as you identified for a full workaround.

This behavior has been in the generator for a very long time, from what I can tell, so it may be one of those bugs that breaks things when it gets fixed. It seems that somebody made a design decision to map File schemas to java.io.File, so I hesitate to open a PR that undoes that decision without understanding the original justification.

[joaomlneto]

This also affects the spring generator.

• If the model is named File, it will use java.io.File.
• If the model is named file, it will use org.springframework.core.io.Resource.

[xcq1]

I just stumbled upon this behavior in the kotlin generator. This can be quite confusing since the Kotlin compiler initially reports ambiguous/invalid FQN usages where other JDK classes like java.net.URI are used, so at first glance I suspected some sort of JDK/buildscript issue.

My workaround was to use an import mapping from File to File (so the class is generated as File.kt), and then use a manual post-processing step via Gradle's doLast and fileTree to remove the resulting invalid import File directives in all generated files.

[wing328]

another way is to use the modelNameMappings option to rename the schema "File" to something else (e.g. ModelFile)

ref: https://github.com/openapitools/openapi-generator/blob/master/docs/customization.md#name-mapping

[xcq1]

@wing328 Thanks for the pointer! I thought I already had tried all kinds of mappings, but that is indeed much easier.