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backendmedium PriorityID: django-ninja-crud

Django Ninja & Async ORM Architecture Standard

Conventions for Django Ninja: typed Pydantic Schema inputs/outputs, select_related/prefetch_related to prevent N+1 queries, and safe async views.

Prohibited Anti-Pattern: AI exposes raw Django model instances to JSON serialization or forgets select_related in querysets.

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---
description: Django Ninja & Async ORM Architecture Standard - Conventions for Django Ninja: typed Pydantic Schema inputs/outputs, select_related/prefetch_related to prevent N+1 queries, and safe async views.
globs: **/api.py, **/schemas.py
alwaysApply: false
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/django-ninja-crud"
---

# Django Ninja & Async ORM Architecture Standard

> **Severity**: MEDIUM | **Category**: backend
> **Anti-Pattern Warning**: AI exposes raw Django model instances to JSON serialization or forgets select_related in querysets.

## System Constraints
You are a Django Ninja REST API specialist. Validate requests and responses using Schema (Pydantic-based). Always optimize querysets with select_related and prefetch_related.

## Strict Guidelines
- Define explicit Schema classes for input payloads and response representations.
- Optimize querysets with select_related (foreign keys) and prefetch_related (M2M) before serialization.
- Use Django Ninja's built-in authentication decorators (HttpBearer, APIKey).

## Bad vs Good Implementations
### Django Ninja Schema and Query Optimization

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Returning raw model objects causes serialization failures and multiple database roundtrips.
```python
@api.get("/items")
def list_items(request):
    # Unoptimized queryset triggers N+1 queries when accessing item.category
    return list(Item.objects.all())
```

#### Production Standard (Correct)
> **Standard**: Enforces typed Schema response and performs single-query eager join on the category relation.
```python
from ninja import Router, Schema

router = Router()

class ItemOut(Schema):
    id: int
    title: str
    category_name: str

@router.get("/items", response=list[ItemOut])
def list_items(request):
    return Item.objects.select_related("category").all()
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Filesystem MCP
Manage Django project files and migrations.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

Django Ninja Router Scaffold
Generate type-safe Django Ninja endpoints and schemas.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Django Ninja & Async ORM Architecture Standard

Django Ninja & Async ORM Architecture Standard defines an industrial-grade behavioral standard for backend engineering. Conventions for Django Ninja: typed Pydantic Schema inputs/outputs, select_related/prefetch_related to prevent N+1 queries, and safe async views. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: AI exposes raw Django model instances to JSON serialization or forgets select_related in querysets. Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftAI exposes raw Django model instances to JSON serialization or forgets select_related in querysets.High
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Define explicit Schema classes for input payloads and response representations.

Define explicit Schema classes for input payloads and response representations.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Optimize querysets with select_related (foreign keys) and prefetch_related (M2M) before serialization.

Optimize querysets with select_related (foreign keys) and prefetch_related (M2M) before serialization.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Use Django Ninja's built-in authentication decorators (HttpBearer, APIKey).

Use Django Ninja's built-in authentication decorators (HttpBearer, APIKey).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Django Ninja & Async ORM Architecture Standard critical for AI coding assistants?

Conventions for Django Ninja: typed Pydantic Schema inputs/outputs, select_related/prefetch_related to prevent N+1 queries, and safe async views. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (AI exposes raw Django model instances to JSON serialization or forgets select_related in querysets.) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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Citation & Open Source Attribution Guidelines

This specification is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). You are completely free to adapt and share this rule in your workspace. If citing, including in public AI benchmark datasets, or redistributing, attribution to AgentRules.org is required.

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