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• 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?
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Description

When calling an API with a null date, you can't because the typescript type is wrong, and if you fudge it, it will throw an error because .toISOString does not exist on null.

openapi-generator version

5.3.0

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  title: Example
  version: v1
paths: {}
components:
  schemas:
    Date:
      type: string
      format: date-time
      nullable: true

Generation Details

{
  "$schema": "node_modules/@openapitools/openapi-generator-cli/config.schema.json",
  "spaces": 2,
  "generator-cli": {
    "version": "5.3.0",
    "generators": {
      "user-api": {
        "generatorName": "typescript-fetch",
        "output": "src/libs/user-api",
        "inputSpec": "https://.../users/v1/docs/spec/public/users/openapi.yml",
        "additionalProperties": {
          "modelPropertyNaming": "original",
          "enumNameSuffix": ""
        }
      }
    }
  }
}

Steps to reproduce

Run openapi-generator-cli generate

Related issues/PRs

Suggest a fix

Make types:

col?: Date | null;

Make coverter:

'col': value.col === undefined ? undefined : (value.date_of_birth.toISOString()),