How to Implement DataLoader Pattern in Go GraphQL

Go does not have a built-in DataLoader pattern; you must implement batching and caching manually using goroutines and channels. Create a batcher that collects requests over a short window, executes a single bulk query, and returns results to individual callers.

func BatchLoader(ctx context.Context, ids []string) ([]Result, error) {
    // 1. Collect IDs from concurrent requests
    // 2. Execute single DB query: SELECT * FROM table WHERE id IN (?)
    // 3. Map results back to original request order
    return db.Query(ctx, "SELECT * FROM items WHERE id IN (?)", ids)
}

Use a sync.Map or context.WithCancel to manage in-flight batches and prevent duplicate queries for the same IDs within a single request cycle.

The DataLoader pattern prevents your application from making hundreds of tiny database queries when loading related data. Instead, it groups these requests into one big query, saving time and server resources. Think of it like a grocery store delivery service that combines multiple neighborhood orders into a single truck trip rather than sending a separate driver for each house.