[BUG] [Rust] SIMPLIFY_ONEOF_ANYOF=false causes NullPointerException: ... "name" is null in AbstractRustCodegen.sanitizeIdentifier

[JMLX42]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Exception in thread "main" java.lang.RuntimeException: Could not process model 'list_accessor_sparse_indices_4XX_response_allOf_errors_inner_source'.Please make sure that your schema is correct!
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:518)
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:443)
        at org.openapitools.codegen.DefaultGenerator.generate(DefaultGenerator.java:1293)
        at org.openapitools.codegen.cmd.Generate.execute(Generate.java:535)
        at org.openapitools.codegen.cmd.OpenApiGeneratorCommand.run(OpenApiGeneratorCommand.java:32)
        at org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:66)
Caused by: java.lang.NullPointerException: Cannot invoke "String.replaceAll(String, String)" because "name" is null
        at org.openapitools.codegen.languages.AbstractRustCodegen.sanitizeIdentifier(AbstractRustCodegen.java:187)
        at org.openapitools.codegen.languages.AbstractRustCodegen.toModelName(AbstractRustCodegen.java:349)
        at org.openapitools.codegen.languages.RustClientCodegen.fromModel(RustClientCodegen.java:295)
        at org.openapitools.codegen.DefaultGenerator.processModels(DefaultGenerator.java:1755)
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:513)
        ... 5 more

openapi-generator version

7.13.0

OpenAPI declaration file content or url

{
  "openapi": "3.1.0",
  "paths": {
    "/api/accessor-sparse-indices/": {
      "get": {
        "tags": [
          "Accessor Sparse Indices"
        ],
        "operationId": "list_accessor_sparse_indices",
        "parameters": [
          {
            "name": "fields[accessor-sparse-indices]",
            "in": "query",
            "description": "Specifies which fields should be returned. The value **MUST** be a comma-separated\n(U+002C COMMA, “,”) list that refers to the name(s) of the fields to be returned.\n\nAn empty value indicates that no fields should be returned.\n\nOmitting this parameter indicates that all fields should be returned.",
            "required": false,
            "schema": {
              "type": "array",
              "items": {
                "type": "string",
                "enum": [
                  "bufferView",
                  "byteOffset",
                  "componentType"
                ]
              }
            },
            "explode": false
          },
          {
            "name": "include",
            "in": "query",
            "required": false,
            "schema": {
              "type": "array",
              "items": {
                "type": "string",
                "enum": [
                  "bufferView"
                ]
              }
            },
            "explode": false
          },
          {
            "name": "page[number]",
            "in": "query",
            "required": false,
            "schema": {
              "type": "integer",
              "format": "int64",
              "default": 1
            },
            "allowReserved": true,
            "example": 1
          },
          {
            "name": "page[size]",
            "in": "query",
            "required": false,
            "schema": {
              "type": "integer",
              "format": "int64",
              "default": 100
            },
            "allowReserved": true,
            "example": 100
          }
        ],
        "responses": {
          "4XX": {
            "description": "Client error response.",
            "content": {
              "application/vnd.api+json": {
                "schema": {
                  "allOf": [
                    {
                      "type": "object",
                      "required": [
                        "errors"
                      ],
                      "properties": {
                        "errors": {
                          "type": "array",
                          "items": {
                            "type": "object",
                            "required": [
                              "status",
                              "title",
                              "detail"
                            ],
                            "properties": {
                              "status": {
                                "type": "string",
                                "example": "404"
                              },
                              "title": {
                                "type": "string",
                                "example": "Not found"
                              },
                              "detail": {
                                "type": "string",
                                "example": "The requested resource cannot be found."
                              },
                              "source": {
                                "oneOf": [
                                  {
                                    "type": "null"
                                  },
                                  {
                                    "$ref": "#/components/schemas/Source"
                                  }
                                ]
                              }
                            }
                          }
                        }
                      }
                    }
                  ]
                },
                "example": "\n{\n  \"errors\": [\n    {\n      \"status\": \"404\",\n      \"title\": \"Resource not found\",\n      \"detail\": \"The requested resource could not be found.\"\n    }\n  ]\n}\n"
              }
            }
          },

Generation Details

$ java -DloggerPath=conf/log4j.properties -jar openapi-generator-cli.jar generate -i ${INPUT_FILE} \
        -g rust \
        -o ${TMP_PATH} \
        --openapi-normalizer=SIMPLIFY_ONEOF_ANYOF=false \
        --additional-properties=avoidBoxedModels=true

Steps to reproduce

$ java -DloggerPath=conf/log4j.properties -jar openapi-generator-cli.jar generate -i ${INPUT_FILE} \
        -g rust \
        -o ${TMP_PATH} \
        --openapi-normalizer=SIMPLIFY_ONEOF_ANYOF=false \
        --additional-properties=avoidBoxedModels=true

Related issues/PRs

• [BUG] OneOf problem #15867
• Fixes so that a oneOf schema with a single sub-schema is simplified #21043

[dctaf]

This bug prevents generating common schemas from OpenAPI specs generated by FastAPI, e.g.:

class SomeResponseBody(BaseModel):
  field_name: Annotated[str | None, Field()] = None

Here is a simpler test case:

{
  "openapi": "3.1.0",
  "info": {
    "version": "0.1",
    "title": "test case"
  },
  "paths": {
    "/api/get": {
      "get": {
        "operationId": "getter",
        "parameters": [],
        "responses": {
          "200": {
            "description": "description",
            "content": {
              "application/json": {
                "schema": {
                  "properties": {
                    "field_name": {
                      "anyOf": [
                        {
                          "type": "string"
                        },
                        {
                          "type": "null"
                        }
                      ]
                    }
                  },
                  "additionalProperties": false,
                  "type": "object"
                }
              }
            }
          }
        }
      }
    }
  }
}

Changing additionalProperties to true does not change the behavior.

Adding distinct "title" fields to each of the anyOf variants causes generation to succeed.

Generation Details

$ docker run --rm openapitools/openapi-generator-cli:latest version
7.16.0-SNAPSHOT
$ docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli:latest generate \
      -i /local/minimal.json \
      -g rust \
      -o /local/openapi \
      --global-property debugModels,debugOpenAPI

debugOpenAPI output

Note the broken anyOf definition

{
  "openapi" : "3.1.0",
  "info" : {
    "title" : "test case",
    "version" : "0.1"
  },
  "servers" : [ {
    "url" : "/"
  } ],
  "paths" : {
    "/api/get" : {
      "get" : {
        "operationId" : "getter",
        "parameters" : [ ],
        "responses" : {
          "200" : {
            "content" : {
              "application/json" : {
                "schema" : {
                  "additionalProperties" : { },
                  "properties" : {
                    "field_name" : {
                      "anyOf" : [ { }, { } ]
                    }
                  }
                }
              }
            },
            "description" : "description"
          }
        }
      }
    }
  }
}

Stack Trace

Similar to top comment.

[main] WARN  o.o.c.languages.AbstractRustCodegen - models::null cannot be used as a field/variable name. Renamed to models_colon_colon_null
[main] WARN  o.o.c.languages.AbstractRustCodegen - models::null cannot be used as a field/variable name. Renamed to models_colon_colon_null
[main] WARN  o.o.c.languages.AbstractRustCodegen - models::null cannot be used as a field/variable name. Renamed to models_colon_colon_null
Exception in thread "main" java.lang.RuntimeException: Could not process model 'getter_200_response_field_name'.Please make sure that your schema is correct!
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:518)
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:443)
        at org.openapitools.codegen.DefaultGenerator.generate(DefaultGenerator.java:1291)
        at org.openapitools.codegen.cmd.Generate.execute(Generate.java:535)
        at org.openapitools.codegen.cmd.OpenApiGeneratorCommand.run(OpenApiGeneratorCommand.java:32)
        at org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:66)
Caused by: java.lang.NullPointerException: Cannot invoke "String.replaceAll(String, String)" because "name" is null
        at org.openapitools.codegen.languages.AbstractRustCodegen.sanitizeIdentifier(AbstractRustCodegen.java:187)
        at org.openapitools.codegen.languages.AbstractRustCodegen.toModelName(AbstractRustCodegen.java:353)
        at org.openapitools.codegen.languages.RustClientCodegen.fromModel(RustClientCodegen.java:365)
        at org.openapitools.codegen.DefaultGenerator.processModels(DefaultGenerator.java:1753)
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:513)

[wing328]

    --openapi-normalizer=SIMPLIFY_ONEOF_ANYOF=false \

what about simply setting the rule to true (which is the default)?

[dctaf]

The :latest Docker image fails on the minimal repro I provided with or without the --openapi-normalizer= flag.

v7.16.0 succeeds w/ or w/o the flag.