> ## Documentation Index
> Fetch the complete documentation index at: https://docs.portkey.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Controlled Generations

> Controlled Generations ensure that the model always follows your supplied [JSON schema](https://json-schema.org/overview/what-is-jsonschema). The Prisma AIRS AI Gateway supports Vertex AI's Controlled Generations feature out of the box with our SDKs & APIs. 

Controlled Generations allows you to constrain model responses to predefined sets of values. This is particularly useful for classification tasks, multiple choice responses, and structured data extraction.

<Note>
  This feature is available for `Gemini 1.5 Pro` & `Gemini 1.5 Flash` models.
</Note>

## With Pydantic & Zod

The OpenAI SDKs for [Python](https://github.com/openai/openai-python/blob/main/helpers.md#structured-outputs-parsing-helpers) and [JavaScript](https://github.com/openai/openai-node/blob/master/helpers.md#structured-outputs-parsing-helpers) also make it easy to define object schemas using [Pydantic](https://docs.pydantic.dev/latest/) and [Zod](https://zod.dev/) respectively. Below, you can see how to extract information from unstructured text that conforms to a schema defined in code.

<Tabs>
  <Tab title="Zod with NodeJS">
    To use Zod with VerteX AI you will also need to import `{ zodResponseFormat }` from `openai/helpers/zod`
  </Tab>
</Tabs>

## Using Enums

You can also use enums to constrain the model's output to a predefined set of values. This is particularly useful for classification tasks and multiple choice responses.

## Using JSON schema Directly

This method is more portable across different languages and doesn't require additional libraries, but lacks the integrated type checking of the Pydantic/Zod approach. Choose the method that best fits your project's needs.

<Tabs>
  <Tab title="cURL">
    ```sh theme={"system"}
    curl https://aigw.portkey.ai/v1/chat/completions \
      -H "Authorization: Bearer $PORTKEY_API_KEY" \
      -H "x-portkey-provider: $VERTEX_PROVIDER" \
      -H "Content-Type: application/json" \
      -d '{
        "model": "gemini-1.5-pro-002",
        "messages": [
          {
            "role": "system",
            "content": "You are a helpful math tutor. Guide the user through the solution step by step."
          },
          {
            "role": "user",
            "content": "how can I solve 8x + 7 = -23"
          }
        ],
        "response_format": {
          "type": "json_schema",
          "json_schema": {
            "name": "math_reasoning",
            "schema": {
              "type": "object",
              "properties": {
                "steps": {
                  "type": "array",
                  "items": {
                    "type": "object",
                    "properties": {
                      "explanation": { "type": "string" },
                      "output": { "type": "string" }
                    },
                    "required": ["explanation", "output"],
                    "additionalProperties": false
                  }
                },
                "final_answer": { "type": "string" }
              },
              "required": ["steps", "final_answer"],
              "additionalProperties": false
            },
            "strict": true
          }
        }
      }'
    ```
  </Tab>
</Tabs>

For more, refer to Google Vertex AI's [detailed documentation on Controlled Generations here](https://cloud.google.com/docs/authentication/provide-credentials-adc#local-dev).


## Related topics

- [Image Generation](/docs/aigw/product/ai-gateway/multimodal-capabilities/image-generation.md)
- [Open Library MCP server](/docs/aigw/integrations/mcp-servers/open-library-mcp-server.md)
- [Claude Desktop for Developers](/docs/aigw/integrations/libraries/claude-desktop-developers.md)
- [Image Generation with Open WebUI](/docs/aigw/integrations/libraries/openwebui/image-generation-with-openwebui.md)
- [OAuth Client Metadata](/docs/aigw/product/mcp-gateway/authentication/oauth-client-metadata.md)