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If you aren’t using Shopify or Square, or if you need to pull data from multiple sources, you can easily implement a Custom Backend.

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Implementation

To create a custom backend, you simply need to implement one or more of the core interfaces: ProductBackend, CartBackend, or OrderBackend.

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Example: MySQL/Postgres Backend

import { ProductBackend, Product } from '@betterdata/commerce-gateway';

class MyDatabaseBackend implements ProductBackend {
  async searchProducts(query: string): Promise<ProductSearchResult> {
    const results = await db.products.findMany({
      where: { name: { contains: query } }
    });
    
    return {
      products: results.map(this.mapToProduct),
      total: results.length,
      hasMore: false,
    };
  }

  async getProductDetails(id: string): Promise<Product | null> {
    const product = await db.products.findUnique({ where: { id } });
    return product ? this.mapToProduct(product) : null;
  }

  private mapToProduct(raw: any): Product {
    return {
      id: raw.id,
      name: raw.title,
      price: { amount: raw.price, currency: 'USD' },
      // ...
    };
  }
}

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Using your Backend

Once implemented, pass your custom class to the gateway: 
const gateway = new LLMGateway({
  backends: {
    products: new MyDatabaseBackend(),
  }
});

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Hybrid Backends

You can also mix and match. For example, use Shopify for product data but a Custom API for complex loyalty points or custom fulfillment rules. 
const gateway = new LLMGateway({
  backends: {
    products: new ShopifyBackend(...),
    cart: new MyCustomLoyaltyCartBackend(...),
  }
});

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Best Practices

  • Timeout Management: Ensure your custom backend methods have sensible timeouts to prevent blocking the LLM interaction.
  • Validation: Use Zod within your backend to validate data coming from your internal services.
  • Error Mapping: Map your internal database errors to the gateway’s Standard Error Types.