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)

// 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

import { PostHogError } from '@posthog/sdk';

async function safePostHogCall<T>(
  operation: () => Promise<T>
): 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

async function withRetry<T>(
  operation: () => Promise<T>,
  maxRetries = 3,
  backoffMs = 1000  # 1000: 1 second in ms
): Promise<T> {
  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)

const clients = new Map<string, PostHogClient>();

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

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

import { z } from 'zod';

const posthogResponseSchema = z.object({
  id: z.string(),
  status: z.enum(['active', 'inactive']),
  createdAt: z.string().datetime(),
});

Resources

• PostHog SDK Reference
• PostHog API Types
• Zod Documentation

Next Steps

Apply patterns in posthog-core-workflow-a for real-world usage.