Supporting response_format for structured outputs

[codelion]

We now support structured outputs using response_format. You can use any HF model (prefix with json) with the standard OpenAI response_format field as follows (supports both pydantic types and json schema):

import os
from openai import OpenAI
import time
from pydantic import BaseModel, Field

OPENAI_BASE_URL = "http://localhost:8000/v1"
OPENAI_API_KEY = "optillm"
client = OpenAI(api_key=OPENAI_API_KEY, base_url=OPENAI_BASE_URL)

class Employee(BaseModel):
    full_name: str
    title: str
    employee_id: str
    email: str
    phone: str

class Employees(BaseModel):
    employees: list[Employee]

class Response(BaseModel):
    think: str # = Field(min_length=1024, max_length=4096)
    response: Employees

schema = {
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "definitions": {
    "Employee": {
      "type": "object",
      "properties": {
        "full_name": { "type": "string" },
        "title": { "type": "string" },
        "employee_id": { "type": "string" },
        "email": { "type": "string" },
        "phone": { "type": "string" }
      },
      "required": ["full_name", "title", "employee_id", "email", "phone"]
    },
    "Employees": {
      "type": "object",
      "properties": {
        "employees": {
          "type": "array",
          "items": { "$ref": "#/definitions/Employee" }
        }
      },
      "required": ["employees"]
    }
  },
  "properties": {
    "think": {
      "type": "string",
    },
    "response": { "$ref": "#/definitions/Employees" }
  },
  "required": ["think", "response"]
}

messages=[
{
"role": "user",
"content": '''Hi, I need to create an employee directory for our small HR team. Here are the details of our new hires:John 
  Smith - hired as Senior Developer, employee ID AD789, contact: jsmith@acmetech.com, (555) 234-5678
  Maria Garcia - hired as Product Manager, employee ID PM456, contact: mgarcia@acmetech.com, (555) 345-6789
  Robert Chen - hired as UX Designer, employee ID UX123, contact: rchen@acmetech.com, (555) 456-7890
  
  Could you format this into a nice directory with their contact details and roles?'''}
]

response = client.chat.completions.create(
  model = "json-deepseek-ai/DeepSeek-R1-Distill-Qwen-1.5B",  # prefix json to use the json plugin
  messages=messages,
  temperature=0.6,
  max_tokens=4096,
  # response_format = Response,
  response_format = {
        "type": "json_schema",
        "json_schema": schema,
    },
)

print(response.choices[0].message.content)

This will give the output:

{
  "think": "The user is providing a list of new hires with their details, including their roles and contact details.",
  "response": {
    "employees": [
      {
        "full_name": "John Smith",
        "title": "Senior Developer",
        "employee_id": "AD789",
        "email": "jsmith@acmetech.com",
        "phone": "(555) 234-5678"
      },
      {
        "full_name": "Maria Garcia",
        "title": "Product Manager",
        "employee_id": "PM456",
        "email": "mgarcia@acmetech.com",
        "phone": "(555) 345-6789"
      },
      {
        "full_name": "Robert Chen",
        "title": "UX Designer",
        "employee_id": "UX123",
        "email": "rchen@acmetech.com",
        "phone": "(555) 456-7890"
      }
    ]
  }
}