Serialization to openapi of org.springframework.data.domain.Sort is not done correctly

[a-locatelli]

Hi,
There is something wrong with the serialization (to openapi) of the org.springframework.data.domain.Sort

I've a method which returns a org.springframework.data.domain.Page from a method in a RestController class.
The implementation of org.springframework.data.domain.Page is org.springframework.data.domain.PageImpl

@RestController
public class MyRestController {

  @PostMapping(path = "/", produces = APPLICATION_JSON_VALUE, consumes = APPLICATION_JSON_VALUE)
  @Operation(operationId="myOperation")
  public org.springframework.data.domain.Page<MyDto> queryMyDto(@RequestBody MyDtoQuery query, @ParameterObject org.springframework.data.domain.Pageable pageable) {
    // This return a PageImpl with the data, the method parameter 'query' is a pojo containg filter properties
    return myService.getResult(query, pageable); 
  }
}

The openapi defintion generated is:

"PageMyDto": {
  "type": "object",
  "properties": {
    "totalPages": {
      "type": "integer",
      "format": "int32"
    },
    "totalElements": {
      "type": "integer",
      "format": "int64"
    },
    "first": {
      "type": "boolean"
    },
    "last": {
      "type": "boolean"
    },
    "size": {
      "type": "integer",
      "format": "int32"
    },
    "content": {
      "type": "array",
      "items": {
        "$ref": "#/components/schemas/MyDto"
      }
    },
    "number": {
      "type": "integer",
      "format": "int32"
    },
    "sort": {
      "$ref": "#/components/schemas/SortObject"
    },
    "numberOfElements": {
      "type": "integer",
      "format": "int32"
    },
    "pageable": {
      "$ref": "#/components/schemas/PageableObject"
    },
    "empty": {
      "type": "boolean"
    }
  }
},
"SortObject": {
  "type": "object",
  "properties": {
    "empty": {
      "type": "boolean"
    },
    "sorted": {
      "type": "boolean"
    },
    "unsorted": {
      "type": "boolean"
    }
  }
}

When i call the method, the return object is (content is empty for this example):

http://localhost:8180/?page=0&size=20

{
  "number": 0,
  "numberOfElements": 0,
  "totalElements": 0,
  "totalPages": 0,
  "size": 20,
  "sort": [],
  "content": []
}

As you can see, the "sort" property generated is not an array, and the SortObject does not contains the Sort properties like orders.

If i set the query parameter sort, the result is:

http://localhost:8180/?page=0&size=20&sort=id

{
  "number": 0,
  "numberOfElements": 0,
  "totalElements": 0,
  "totalPages": 0,
  "size": 20,
  "sort": [
    {
      "property": "id",
      "direction": "ASC",
      "ignoreCase": false,
      "nullHandling": "NATIVE"
    }
  ],
  "content": []
}

I'm using spring boot 3.1.6 and springdoc-openapi-webmvc-ui 2.3.0.

Can you help me figure out if there is a bug or if i'm doing something wrong?

Thanks

[Jodee90]

@a-locatelli Did you manage to solve this? Any workarounds?

[bnasslahsen]

@a-locatelli,

I have added a fix for it.
Let me know if the fix works for you with the latest snapshot.

[SimoneFalzone]

I have the same problem, and your fix dosen't solved it.

Your excpected output is:

"sort": {
     "$ref": "#/components/schemas/SortObject"
},

But have to be:

"sort": {
  "type": "array",
  "items": {
    "$ref": "#/components/schemas/OrderObject"
  }
},

I implemented a workaround like this, with this the desired openapi.json is generated and from that working DTOs to use with Pageable and Sort.

@Configuration
class CustomOpenApiConfiguration {

    @Bean
    fun CustomSortSchemaConverter(): SortSchemaConverter {
        // Create and return the custom SortSchemaConverter
        return SortSchemaConverter()
    }
}

class SortSchemaConverter : ModelConverter {

    override fun resolve(
        type: AnnotatedType,
        context: ModelConverterContext,
        chain: MutableIterator<ModelConverter>
    ): Schema<*>? {
        val javaType = type.type

        return if (javaType is SimpleType && javaType.rawClass == Sort::class.java) {

            val orderSchema = ObjectSchema()
                .addProperty("direction", StringSchema())
                .addProperty("property", StringSchema())
                .addProperty("ignoreCase", BooleanSchema())
                .addProperty("nullHandling", StringSchema())
                .addProperty("ascending", BooleanSchema())
                .addProperty("descending", BooleanSchema())
            //  needs to be called whenever a Model is defined which can be referenced from another
            //  Model or Property
            context.defineModel("OrderObject", orderSchema)

            ArraySchema().items(
                Schema<Any>().`$ref`("#/components/schemas/OrderObject")
            )

        } else if (chain.hasNext()) {
            chain.next().resolve(type, context, chain)
        } else {
            null
        }
    }
}

[bnasslahsen]

@SimoneFalzone,

Your proposed fix is too much lines of code, with too much assumptions that OrderObject schema exists.
There is much simpler way to do this.