| --- |
| license: mit |
| tags: |
| - fastapi |
| - gemini |
| - google-genai |
| - pydantic |
| - structured-outputs |
| - micro-saas |
| --- |
| |
| # ⚡ FastAPI + Google Gemini 2026 Structured JSON Blueprint (Python 3.13 Ready) |
|
|
| [](https://github.com/RAZIO05/fastapi-gemini-2026-blueprint/actions) |
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|
|
| <p align="center"> |
| <a href="https://yahiaoui26.gumroad.com/l/shipai-pro/LAUNCH20"> |
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| </a> |
| </p> |
| |
| > **Stop fighting unstructured LLM markdown and Python 3.13 `bcrypt` crashes.** |
| > This reference blueprint shows how to wire **FastAPI**, **Pydantic v2**, and the official **`google-genai` SDK** with native `response_mime_type="application/json"` and 3-model automatic failover. |
|
|
| --- |
|
|
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|
|
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|
|
| --- |
|
|
| ## 1. Enforcing Strict Pydantic v2 JSON with 3-Model Gemini Failover |
|
|
| ```python |
| import os, json |
| from google import genai |
| from pydantic import BaseModel |
| from typing import List |
| |
| client = genai.Client(api_key=os.getenv("GEMINI_API_KEY")) |
| |
| DEFAULT_MODELS = [ |
| os.getenv("GEMINI_MODEL", "gemini-3.5-flash"), |
| "gemini-flash-lite-latest", |
| "gemini-3.8-flash", |
| ] |
| |
| class AIStructuredResponse(BaseModel): |
| status: str |
| summary: str |
| key_points: List[str] |
| action_items: List[str] |
| |
| def generate_structured_json(prompt: str, system_instruction: str) -> AIStructuredResponse: |
| for model_name in DEFAULT_MODELS: |
| try: |
| res = client.models.generate_content( |
| model=model_name, |
| contents=prompt, |
| config={ |
| "response_mime_type": "application/json", |
| "system_instruction": system_instruction, |
| }, |
| ) |
| return AIStructuredResponse(**json.loads(res.text)) |
| except Exception as err: |
| if any(code in str(err) for code in ("404", "503", "UNAVAILABLE", "NOT_FOUND")): |
| continue |
| raise |
| ``` |
|
|
| ## 2. Fixing the Python 3.12 / 3.13 `passlib[bcrypt]` 72-Byte Startup Crash |
|
|
| Pin `bcrypt==4.0.1` alongside `passlib[bcrypt]` in `requirements.txt` to avoid the `ValueError: password cannot be longer than 72 bytes` exception during container boot: |
|
|
| ```txt |
| fastapi |
| uvicorn |
| google-genai |
| pydantic[email] |
| passlib[bcrypt] |
| bcrypt==4.0.1 |
| python-jose[cryptography] |
| ``` |
|
|
| --- |
|
|
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|
|
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|
|
