[BUG] OpenAPI Generator fails to generate array models

[segevfiner]

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

OpenAPI generator fails to generate array models. It complains with:

[main] INFO  o.o.codegen.DefaultGenerator - Model {} not generated since it's an alias to array (without property) and `generateAliasAsModel` is set to false (default)

openapi-generator version

v4.3.1

And also tried latest master using Docker 07c23f4.

OpenAPI declaration file content or url

openapi: '3.0.3'

info:
  title: Test
  version: 0.1.0

paths: {}

components:
  schemas:
    Test:
      type: array
      items:
        type: object
        properties:
          foo:
            type: string

Generation Details

docker run --rm \                                
  -v ${PWD}:/local openapitools/openapi-generator-cli generate \    
  -i /local/openapi.yaml \ 
  -g go \
  -o /local/out/go

Steps to reproduce

1. Generate a client for any language using the provided schema. Note that the array model is not generated with the log message from this bug's description.

Related issues/PRs

Suggest a fix

The following code is erroneous. An array has items not properties (Even required by the OpenAPI spec). You might need to cast Schema to ArraySchema to get access to items or something like that.

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java

Lines 485 to 488 in 41851b4

	if (!ModelUtils.isGenerateAliasAsModel(schema) && (schema.getProperties() == null || schema.getProperties().isEmpty())) {
	// schema without property, i.e. alias to array
	LOGGER.info("Model {} not generated since it's an alias to array (without property) and `generateAliasAsModel` is set to false (default)", name);
	continue;

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[wing328]

Did you try setting the generateAliasAsModel option to true?

[segevfiner]

It then generates models with just a plain map[string]interface{} (A generic type) instead of the nested type. This isn't an "alias model" that just aliases a plain array with no items type. I tried changing that if to:

diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java
index 24f407c08a..de212afa58 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java
@@ -26,6 +26,7 @@ import io.swagger.v3.oas.models.Paths;
 import io.swagger.v3.oas.models.info.Contact;
 import io.swagger.v3.oas.models.info.Info;
 import io.swagger.v3.oas.models.info.License;
+import io.swagger.v3.oas.models.media.ArraySchema;
 import io.swagger.v3.oas.models.media.Schema;
 import io.swagger.v3.oas.models.parameters.Parameter;
 import io.swagger.v3.oas.models.security.*;
@@ -482,9 +483,11 @@ public class DefaultGenerator implements Generator {
                         continue;
                     }
                 } else if (ModelUtils.isArraySchema(schema)) { // check to see if it's an "array" model
-                    if (!ModelUtils.isGenerateAliasAsModel(schema) && (schema.getProperties() == null || schema.getProperties().isEmpty())) {
-                        // schema without property, i.e. alias to array
-                        LOGGER.info("Model {} not generated since it's an alias to array (without property) and `generateAliasAsModel` is set to false (default)", name);
+                    if (!ModelUtils.isGenerateAliasAsModel(schema) && (((ArraySchema) schema).getItems() == null ||
+                            (!ModelUtils.isComposedSchema(((ArraySchema) schema).getItems()) &&
+                                ((ArraySchema) schema).getItems().getProperties() == null || ((ArraySchema) schema).getItems().getProperties().isEmpty()))) {
+                        // schema without items, i.e. alias to array
+                        LOGGER.info("Model {} not generated since it's an alias to array (without items) and `generateAliasAsModel` is set to false (default)", name);
                         continue;
                     }
                 }

But that only fixes it so that it isn't wrongly detected as an alias model. The inner items model is still not generated and used.

[romnus]

Hi All, I believe this bug is causing my Apex code not to compile.

Like @segevfiner I get the
[main] INFO o.o.codegen.DefaultGenerator - Model {} not generated since it's an alias to array (without property) and generateAliasAsModel is set to false (default) warning. Then when I deploy my sandbox org, I get errors like Invalid type: OASOneOfnumberbooleanstringdate.

This error appears to originate from an attribute (not sure if that's the term?) in one of the API schemas (Open API 3.0):

          "cutsheetOptions": {
            "type": "array",
            "description": "List of options that meet the provided search criteria, if any.",
            "items": {
              "type": "object",
              "properties": {
                "name": {
                  "type": "string"
                },
                "value": {
                  "description": "Cutsheet property value.",
                  "oneOf": [
                    {
                      "type": "number"
                    },
                    {
                      "type": "boolean"
                    },
                    {
                      "type": "string"
                    },
                    {
                      "type": "string",
                      "format": "date"
                    }
                  ]
                },
                "modelParts": {
                  "type": "array",
                  "description": "A list of model parts that provide the given property value.",
                  "items": {
                    "type": "object",
                    "properties": {
                      "modelPart": {
                        "type": "string"
                      },
                      "option": {
                        "type": "string"
                      }
                    }
                  }
                }
              }
            }
          }

Setting generateAliasAsModel results in these errors and others.

It looks like the code generator is interpreting the oneOf attribute incorrectly? I'm new to all this so excuse any incoherence, but eager to figure out what the issue is.

[janekolszak]

Any news?

A colleague and I were able to reproduce this with v3.3.4 and the latest v5.0.1 (deployed via the wget method, as per the installation instructions).

This use case seems to be right out of the Swagger examples (i.e. array of objects), so it seems odd that this error would arise with recent builds given it's likely a common/typical use case in OpenAPI-generated APIs/specs.

Edit: we were able to get it going by using a recent build (i.e. v5.0.1) plus the --generate-alias-as-model flag to the tool. The question remains: does it make sense that one should have to explicitly set said flag/option for such a use case?

Edit: nope: using the --generate-alias-as-model flag just makes the compilation errors go away. The actual auto-generated code is empty (i.e. blank schema).

[shimmerLum]

Hello,
I was having the same issue with Model {} not generated since it's an alias to array (without property) and `generateAliasAsModel` is set to false (default) when trying to generate a model for python-flask, so I also tried setting generateAliasAsModel when running the OpenAPI Generator.

I tested this with openapi-generator-cli-5.1.0-20210108.143511-2.jar

I used this command:

java -jar openapi-generator-cli-5.1.0-20210108.143511-2.jar generate -g python-flask -i test.yaml -o test_schema/ --generate-alias-as-model --additional-properties packageName=test

... with test.yaml as input. It's an example using the array type, which contains object types (this example is built following the examples from swagger.io for OpenAPI 3.0)

The warning message went away and the generator did generate a model in the following foldertest_schema/test/models - test_schema.py. However, as you can see, the model is wrong, as it did not populate it with the contents of my array (e.g. id, username, name).

The dictionary types are empty:

def __init__(self):  # noqa: E501
        """TestSchema - a model defined in OpenAPI
        """
        self.openapi_types = {
        }

        self.attribute_map = {
        }

I also created another example (using an example from here using just an object, not an array of objects, and the results I get match what I expected. I used test_object.yaml as input and this is the resulting model: test_schema.py

The command used:

java -jar openapi-generator-cli-5.1.0-20210108.143511-2.jar generate -g python-flask -i test_object.yaml -o test_object/  --additional-properties packageName=test

In this instance, the OpenAPI Generator successfully populated the model with the fields, getters and setters for them. Here is the constructor for the object:

    def __init__(self, id=None, username=None, name=None):  # noqa: E501
        """TestSchema - a model defined in OpenAPI
        :param id: The id of this TestSchema.  # noqa: E501
        :type id: int
        :param username: The username of this TestSchema.  # noqa: E501
        :type username: str
        :param name: The name of this TestSchema.  # noqa: E501
        :type name: str
        """
        self.openapi_types = {
            'id': int,
            'username': str,
            'name': str
        }

        self.attribute_map = {
            'id': 'id',
            'username': 'username',
            'name': 'name'
        }

        self._id = id
        self._username = username
        self._name = name

How should I best proceed to be able to generate a non-empty schema for the array-of-objects use case?
Thank you!

@keysight-diana-belmega Thanks for putting this MCVE/PoC together Diana!

[DevSrSouza]

Same issue here with Docker 1.41 spec of ContainerSummary when generating for Kotlin->Multiplatform

[shimmerLum]

Hello!

I found a workaround so that the OpenAPI generator generates valid models when an array is needed.

I tried to wrap the array in a top-level object, like in this example input file test_wrapper.yaml. You can see that the wrapper object is the only difference from my original example and the OpenAPI generator successfully created a good model, without using the --generate-alias-as-model option.

This worked with openapi-generator-cli-5.1.0-20210108.143511-2.jar. I didn't try it with other versions of the generator.

The command I used is:

java -jar openapi-generator-cli-5.1.0-20210108.143511-2.jar generate -g python-flask -i test_wrapper.yaml -o test_wrapper_schema/ --additional-properties packageName=test

...with test_wrapper.yaml as input file.

The files generated in the test_wrapper_schema/test/models folder are: test_schema.py and test_schema_array_wrapper.py, which work well.

You can see that test_schema.py contains a Python list of the generated object test_schema_array_wrapper.py, so it managed to create an object that contains the desired array:

def __init__(self, array_wrapper=None):  # noqa: E501
        """TestSchema - a model defined in OpenAPI
        :param array_wrapper: The array_wrapper of this TestSchema.  # noqa: E501
        :type array_wrapper: List[TestSchemaArrayWrapper]
        """
        self.openapi_types = {
            'array_wrapper': List[TestSchemaArrayWrapper]
        }

        self.attribute_map = {
            'array_wrapper': 'array-wrapper'
        }

        self._array_wrapper = array_wrapper

I don't know if this workaround works for any use-case, but I hope it helps anyone who needs it and maybe aids in solving the bug.

Thanks!

[kumar-tadepalli]

This is applicable for typescript-angular generator as well.

[mmihalev]

Same for PHP clients