---
title: "How should I represent optional fields in OpenAI strict JSON outputs?"  
description: "How should I represent optional fields in OpenAI strict JSON outputs?"  
author: "Waldemar Thiessen"  
published: 2026-10-22  
updated: 2026-10-22  
canonical: https://www.mindstick.com/forum/162766/how-should-i-represent-optional-fields-in-openai-strict-json-outputs  
category: "Structured Outputs"  
tags: ["OpenAI API", "json", "Schema design"]  
reading_time: 1 minute  

---

# How should I represent optional fields in OpenAI strict JSON outputs?

I’m using OpenAI’s strict JSON output mode for records where some fields genuinely may not exist, such as a middle name or a second address line. I’m unsure whether to make those fields nullable, list every key as required, or leave optional properties out of the schema.

What schema pattern has worked reliably for you, especially when the model should return [valid JSON](https://answers.mindstick.com/qa/117825/can-openai-structured-outputs-return-valid-json-with-incorrect-facts) without inventing a value just to fill a field?


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Original Source: https://www.mindstick.com/forum/162766/how-should-i-represent-optional-fields-in-openai-strict-json-outputs

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