📄 ai-sdk/docs/troubleshooting/no-object-generated-content-filter

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Issue

When using generateObject or streamObject with OpenAI's structured output generation, you may encounter a NoObjectGeneratedError with the finish reason content-filter. This error occurs when your Zod schema contains incompatible types that OpenAI's structured output feature cannot process.

// Problematic code - incompatible schema typesimport { generateObject } from 'ai';import { openai } from '@ai-sdk/openai';import { z } from 'zod';
const result = await generateObject({  model: openai('gpt-4o-2024-08-06'),  schema: z.object({    name: z.string().nullish(), // ❌ .nullish() is not supported    email: z.string().optional(), // ❌ .optional() is not supported    age: z.number().nullable(), // ✅ .nullable() is supported  }),  prompt: 'Generate a user profile',});
// Error: NoObjectGeneratedError: No object generated.// Finish reason: content-filter

Background

OpenAI's structured output generation uses JSON Schema under the hood and has specific requirements for schema compatibility. The Zod methods .nullish() and .optional() generate JSON Schema patterns that are incompatible with OpenAI's implementation, causing the model to reject the schema and return a content-filter finish reason.

Solution

Replace .nullish() and .optional() with .nullable() in your Zod schemas when using structured output generation with OpenAI models.

import { generateObject } from 'ai';import { openai } from '@ai-sdk/openai';import { z } from 'zod';
// Correct approach - use .nullable()const result = await generateObject({  model: openai('gpt-4o-2024-08-06'),  schema: z.object({    name: z.string().nullable(), // ✅ Use .nullable() instead of .nullish()    email: z.string().nullable(), // ✅ Use .nullable() instead of .optional()    age: z.number().nullable(),  }),  prompt: 'Generate a user profile',});
console.log(result.object);// { name: "John Doe", email: "john@example.com", age: 30 }// or { name: null, email: null, age: 25 }

Schema Type Comparison

| Zod Type | Compatible | JSON Schema Behavior | | --- | --- | --- | | .nullable() | ✅ Yes | Allows null or the specified type | | .optional() | ❌ No | Field can be omitted (not supported) | | .nullish() | ❌ No | Allows null, undefined, or omitted (not supported) |

Related Information

For more details on structured output generation, see Generating Structured Data
For OpenAI-specific structured output configuration, see OpenAI Provider - Structured Outputs

On this page

Object generation failed with OpenAI

Issue

Background

Solution

Schema Type Comparison

Related Information

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