# GRAPHQL Best Practices

> GraphQL is a query language for APIs that enables clients to ask for Use when this capability is needed.

- Skill: `tomevault-io/graphql-best-practices` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/graphql-best-practices`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/graphql-best-practices/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/graphql-best-practices

---


# Graphql Best Practices

## Skill Profile
*(Select at least one profile to enable specific modules)*
- [ ] **DevOps**
- [x] **Backend**
- [ ] **Frontend**
- [ ] **AI-RAG**
- [ ] **Security Critical**

## Overview
GraphQL is a query language for APIs that enables clients to ask for exactly what they need and nothing more, featuring a strong typing system and self-documenting capabilities.

GraphQL consists of:
- **Query Language**: Query language for fetching data
- **Schema-First**: Schema-driven development approach
- **Strong Typing**: Built-in type system and validation
- **Introspection**: Self-documenting API capabilities
- **Real-Time**: Built-in subscription support for real-time updates
- **Flexible**: Client can request exactly what they need

## Why This Matters
- **Reduce Over-Fetching**: GraphQL can reduce over-fetching by 30-50%
- **Enhance Performance**: Reduced round-trips and data transfer
- **Increase Developer Experience**: Self-documenting improves DX
- **Reduce Bandwidth**: Reduced data transfer with precise queries
- **Improve Type Safety**: Built-in validation improves type safety

---

## Core Concepts & Rules

### 1. Core Principles
- Follow established patterns and conventions
- Maintain consistency across codebase
- Document decisions and trade-offs

### 2. Implementation Guidelines
- Start with the simplest viable solution
- Iterate based on feedback and requirements
- Test thoroughly before deployment


## Inputs / Outputs / Contracts
* **Inputs**:
  - Schema requirements
  - Resolver requirements
  - Authentication requirements
  - Subscription requirements
* **Entry Conditions**:
  - Node.js 16+ is available
  - GraphQL is installed
  - Schema is defined
  - Data sources are available
* **Outputs**:
  - GraphQL schema
  - Resolvers
  - Authentication middleware
  - Subscription setup
* **Artifacts Required (Deliverables)**:
  - Schema definition
  - Resolver implementations
  - DataLoader setup
  - Authentication middleware
  - Subscription handlers
* **Acceptance Evidence**:
  - Queries work correctly
  - Mutations work correctly
  - Subscriptions work correctly
  - DataLoader prevents N+1
* **Success Criteria**:
  - API is functional
  - N+1 problem is solved
  - Subscriptions work
  - Authorization is enforced

## Skill Composition
* **Depends on**: [error-handling](../error-handling/SKILL.md), [validation](../validation/SKILL.md)
* **Compatible with**: [express-rest](../express-rest/SKILL.md), [nodejs-api](../nodejs-api/SKILL.md)
* **Conflicts with**: None
* **Related Skills**: [api-design](../../01-foundations/api-design/SKILL.md), [monitoring-observability](../../14-monitoring-observability/SKILL.md)

---

## Quick Start / Implementation Example

1. Review requirements and constraints
2. Set up development environment
3. Implement core functionality following patterns
4. Write tests for critical paths
5. Run tests and fix issues
6. Document any deviations or decisions

```python
# Example implementation following best practices
def example_function():
    # Your implementation here
    pass
```


## Assumptions / Constraints / Non-goals

* **Assumptions**:
  - Development environment is properly configured
  - Required dependencies are available
  - Team has basic understanding of domain
* **Constraints**:
  - Must follow existing codebase conventions
  - Time and resource limitations
  - Compatibility requirements
* **Non-goals**:
  - This skill does not cover edge cases outside scope
  - Not a replacement for formal training


## Compatibility & Prerequisites

* **Supported Versions**:
  - Python 3.8+
  - Node.js 16+
  - Modern browsers (Chrome, Firefox, Safari, Edge)
* **Required AI Tools**:
  - Code editor (VS Code recommended)
  - Testing framework appropriate for language
  - Version control (Git)
* **Dependencies**:
  - Language-specific package manager
  - Build tools
  - Testing libraries
* **Environment Setup**:
  - `.env.example` keys: `API_KEY`, `DATABASE_URL` (no values)


## Test Scenario Matrix (QA Strategy)

| Type | Focus Area | Required Scenarios / Mocks |
| :--- | :--- | :--- |
| **Unit** | Core Logic | Must cover primary logic and at least 3 edge/error cases. Target minimum 80% coverage |
| **Integration** | DB / API | All external API calls or database connections must be mocked during unit tests |
| **E2E** | User Journey | Critical user flows to test |
| **Performance** | Latency / Load | Benchmark requirements |
| **Security** | Vuln / Auth | SAST/DAST or dependency audit |
| **Frontend** | UX / A11y | Accessibility checklist (WCAG), Performance Budget (Lighthouse score) |


## Technical Guardrails & Security Threat Model

### 1. Security & Privacy (Threat Model)
* **Top Threats**: Injection attacks, authentication bypass, data exposure
- [ ] **Data Handling**: Sanitize all user inputs to prevent Injection attacks. Never log raw PII
- [ ] **Secrets Management**: No hardcoded API keys. Use Env Vars/Secrets Manager
- [ ] **Authorization**: Validate user permissions before state changes

### 2. Performance & Resources
- [ ] **Execution Efficiency**: Consider time complexity for algorithms
- [ ] **Memory Management**: Use streams/pagination for large data
- [ ] **Resource Cleanup**: Close DB connections/file handlers in finally blocks

### 3. Architecture & Scalability
- [ ] **Design Pattern**: Follow SOLID principles, use Dependency Injection
- [ ] **Modularity**: Decouple logic from UI/Frameworks

### 4. Observability & Reliability
- [ ] **Logging Standards**: Structured JSON, include trace IDs `request_id`
- [ ] **Metrics**: Track `error_rate`, `latency`, `queue_depth`
- [ ] **Error Handling**: Standardized error codes, no bare except
- [ ] **Observability Artifacts**:
    - **Log Fields**: timestamp, level, message, request_id
    - **Metrics**: request_count, error_count, response_time
    - **Dashboards/Alerts**: High Error Rate > 5%


## Agent Directives & Error Recovery
*(ข้อกำหนดสำหรับ AI Agent ในการคิดและแก้ปัญหาเมื่อเกิดข้อผิดพลาด)*

- **Thinking Process**: Analyze root cause before fixing. Do not brute-force.
- **Fallback Strategy**: Stop after 3 failed test attempts. Output root cause and ask for human intervention/clarification.
- **Self-Review**: Check against Guardrails & Anti-patterns before finalizing.
- **Output Constraints**: Output ONLY the modified code block. Do not explain unless asked.


## Definition of Done (DoD) Checklist

- [ ] Tests passed + coverage met
- [ ] Lint/Typecheck passed
- [ ] Logging/Metrics/Trace implemented
- [ ] Security checks passed
- [ ] Documentation/Changelog updated
- [ ] Accessibility/Performance requirements met (if frontend)


## Anti-patterns / Pitfalls

* ⛔ **Don't**: Log PII, catch-all exception, N+1 queries
* ⚠️ **Watch out for**: Common symptoms and quick fixes
* 💡 **Instead**: Use proper error handling, pagination, and logging


## Reference Links & Examples

* Internal documentation and examples
* Official documentation and best practices
* Community resources and discussions


## Versioning & Changelog

* **Version**: 1.0.0
* **Changelog**:
  - 2026-02-22: Initial version with complete template structure

---
> Source: [AmnadTaowsoam/CerebraSkills](https://github.com/AmnadTaowsoam/CerebraSkills) — distributed by [TomeVault](https://tomevault.io).
<!-- tomevault:4.0:skill_md:2026-05-22 -->