posthog-sdk-patterns

# PostHog SDK Patterns ## Overview Production-ready patterns for PostHog SDK usage in TypeScript and Python. ## Prerequisites - Completed `posthog-install-auth` setup - Familiarity with async/await patterns - Understanding of error handling best practices ## Instructions ### Step 1: Implement Singleton Pattern (Recommended) ```typescript // src/posthog/client.ts import { PostHogClient } from '@posthog/sdk'; let instance: PostHogClient | null = null; export function getPostHogClient(): PostHogClient { if (!instance) { instance = new PostHogClient({ apiKey: process.env.POSTHOG_API_KEY!, // Additional options }); } return instance; } ``` ### Step 2: Add Error Handling Wrapper ```typescript import { PostHogError } from '@posthog/sdk'; async function safePostHogCall( operation: () => Promise ): Promise<{ data: T | null; error: Error | null }> { try { const data = await operation(); return { data, error: null }; } catch (err) { if (err instanceof PostHogError) { console.error({ code: err.code, message: err.message, }); } return { data: null, error: err as Error }; } } ``` ### Step 3: Implement Retry Logic ```typescript async function withRetry( operation: () => Promise, maxRetries = 3, backoffMs = 1000 ): Promise { for (let attempt = 1; attempt <= maxRetries; attempt++) { try { return await operation(); } catch (err) { if (attempt === maxRetries) throw err; const delay = backoffMs * Math.pow(2, attempt - 1); await new Promise(r => setTimeout(r, delay)); } } throw new Error('Unreachable'); } ``` ## Output - Type-safe client singleton - Robust error handling with structured logging - Automatic retry with exponential backoff - Runtime validation for API responses ## Error Handling | Pattern | Use Case | Benefit | |---------|----------|---------| | Safe wrapper | All API calls | Prevents uncaught exceptions | | Retry logic | Transient failures | Improves reliability | | Type guards | Response validation | Catches API changes | | Logging | All operations | Debugging and monitoring | ## Examples ### Factory Pattern (Multi-tenant) ```typescript const clients = new Map(); export function getClientForTenant(tenantId: string): PostHogClient { if (!clients.has(tenantId)) { const apiKey = getTenantApiKey(tenantId); clients.set(tenantId, new PostHogClient({ apiKey })); } return clients.get(tenantId)!; } ``` ### Python Context Manager ```python from contextlib import asynccontextmanager from posthog import PostHogClient @asynccontextmanager async def get_posthog_client(): client = PostHogClient() try: yield client finally: await client.close() ``` ### Zod Validation ```typescript import { z } from 'zod'; const posthogResponseSchema = z.object({ id: z.string(), status: z.enum(['active', 'inactive']), createdAt: z.string().datetime(), }); ``` ## Resources - [PostHog SDK Reference](https://docs.posthog.com/sdk) - [PostHog API Types](https://docs.posthog.com/types) - [Zod Documentation](https://zod.dev/) ## Next Steps Apply patterns in `posthog-core-workflow-a` for real-world usage.