Schema attributes with inheritance are dropped

[swaechter]

Steps to Reproduce

1.) Clone the example https://github.com/swaechter/openapiproblems
2.) Switch the version number in gradle.properties to 2.4.0 and run the application
3.) Check out the schema model Owner that has an attribute vehicle of the type Car/Bike
4.) Stop the application and update the version number 2.4.1. Run the application
5.) The schema attribute vehicle is now missing, but the schemas Car/Bike still exist. In addition, the Vehicle schema references Car/Bike via oneOf

Expected Behaviour

The vehicle attribute shows up in the editor & is always referenced:

Actual Behaviour

Starting with 2.4.1, the vehicle attribute doesn't show up in the editor & isn't referenced anymore. I am not sure if this is somehow related to @JsonXxX attributes that aren't processed properly (Looking at #471)

Environment Information

• Operating System: Windows 10 x64
• Micronaut Version: Working in 2.4.0, broken in 2.4.1+
• JDK Version: AdoptJDK jdk-11.0.10.9-hotspot

Example Application

https://github.com/swaechter/openapiproblems

[swaechter]

It looks like the schema generation itself is correct. What's broken are the schema references (Schema X has an attribute Y of type Z --> Relationship Z has always the type/value "string" or "object" without $ref). I found these two broken relationships:

• anyOf: An Owner can jave a Car OR Bike, but it has to be of type Vehicle/contain all values of type Vehicle)
• $ref for nested classes or enums: ReadBackupSettingsDto has a backup frequency (Enum with weekday) and a time (Nested class with hour/minutes)

This means the generated OpenAPI code is unusable/broken as soon someone is using nested classes/enums :(

A workaround via custom merged YAML file is quite time consuming (Our YML is around 11k lines long) + using Micronaut 2.4.2 with an older annotation processor/library like 2.2.0 didn't work and 2.1.1 generates some strange BOM mistake (Unable to find ktor-bom on Maven central).

I hope I can find some time to dig into the problem (I always create issues without a PR). Do you know @asodja if the problem is related to your changes and maybe give a tip where to look?

[asodja]

It should not be related, since components ordering is done just before yaml is written to file, so my change does not affect actual schema referencing/creation. This change to your example also proves it:

diff --git a/build.gradle b/build.gradle
index 9e86e3d..0b11b62 100644
--- a/build.gradle
+++ b/build.gradle
@@ -22,8 +22,8 @@ micronaut {
 
 dependencies {
     annotationProcessor("io.micronaut:micronaut-management")
-    annotationProcessor("io.micronaut.openapi:micronaut-openapi")
-    implementation("io.micronaut.openapi:micronaut-openapi")
+    annotationProcessor("io.micronaut.openapi:micronaut-openapi:2.4.0!!")
+    implementation("io.micronaut.openapi:micronaut-openapi:2.4.0!!")
     implementation("io.swagger.core.v3:swagger-annotations")
     implementation("io.micronaut:micronaut-http-client")
     implementation("io.micronaut:micronaut-runtime")
diff --git a/gradle.properties b/gradle.properties
index be22b84..06f1798 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1 +1 @@
-micronautVersion=2.4.2
+micronautVersion=2.4.0

So if you force latest Micronaut openapi that was released yesterday with my change and change Micronaut version to 2.4.0 everything works ok. If you change Micronaut version to >= 2.4.1 request body in example is broken again.

So it looks like something in Micronaut core was changed and affects OpenApi.

---

I did not look into schema code much since I did not fix any issue regarding this. But if I remember correctly you should check AbstractOpenApiEndpointVisitor.java and method:

micronaut-openapi/openapi/src/main/java/io/micronaut/openapi/visitor/AbstractOpenApiEndpointVisitor.java

Line 254 in 9d9f092

public void visitMethod(MethodElement element, VisitorContext context) {

that later calls processParameters() or some similar method. Also check places where Schema class is used.

Most of the code is in this class. Probably the easiest way to debug this is to set breakpoint in that method and then run in OpenApiSchemaInheritanceSpec debug mode and check what is happening here or implement your case and debug it.

I hope that helps.

[asodja]

Also it might be worth debugging, what is going on in:

micronaut-openapi/openapi/src/main/java/io/micronaut/openapi/visitor/AbstractOpenApiVisitor.java

Line 611 in 9d9f092

protected @Nullable Schema resolveSchema(OpenAPI openAPI, @Nullable Element definingElement, ClassElement type, VisitorContext context, List<MediaType> mediaTypes) {

[graemerocher]

It is quite easy to add tests for this project. See https://github.com/micronaut-projects/micronaut-openapi/blob/master/openapi/src/test/groovy/io/micronaut/openapi/visitor/OpenApiComplexSchemaSpec.groovy for an example if you want to come up with a reproducer

[asodja]

I had some time and played with this a bit, and the issue is this line where annotation on property and existing schema are merged:

micronaut-openapi/openapi/src/main/java/io/micronaut/openapi/visitor/AbstractOpenApiVisitor.java

Line 938 in 9d9f092

schemaToBind = jsonMapper.readerForUpdating(schemaToBind).readValue(schemaJson);

It looks like it behaves differently with new Micronaut, it might be due to Jackson upgrade.

This will fix your issue:

diff --git a/src/main/java/ch/swaechter/dto/Owner.java b/src/main/java/ch/swaechter/dto/Owner.java
index c2df9bc..ab82b37 100644
--- a/src/main/java/ch/swaechter/dto/Owner.java
+++ b/src/main/java/ch/swaechter/dto/Owner.java
@@ -36,7 +36,7 @@ public class Owner {
         this.id = id;
     }
 
-    @Schema(description = "Vehicle of the owner. Here a car or bike with a name", oneOf = {Car.class, Bike.class})
+//    @Schema(description = "Vehicle of the owner. Here a car or bike with a name", oneOf = {Car.class, Bike.class})
     public Vehicle getVehicle() {
         return vehicle;
     }
diff --git a/src/main/java/ch/swaechter/dto/Vehicle.java b/src/main/java/ch/swaechter/dto/Vehicle.java
index ac98b96..8161412 100644
--- a/src/main/java/ch/swaechter/dto/Vehicle.java
+++ b/src/main/java/ch/swaechter/dto/Vehicle.java
@@ -14,6 +14,6 @@ import io.swagger.v3.oas.annotations.media.Schema;
         @JsonSubTypes.Type(value = Bike.class, name = "BIKE")
 })
 @Introspected
-@Schema(description = "Vehicle, here a car or a vehicle")
+@Schema(description = "Vehicle, here a car or a vehicle", anyOf = { Car.class, Bike.class })
 public abstract class Vehicle {
 }

So basically: for classes you have to have @Schema on class and not on getter/field to make it work.

I probably won't have time to fix it, but here is a reproducer if you want to find a solution.
asodja@f0491c7