Visualizing AWS DynamoDB Data with React & Recharts

Data stored in DynamoDB is just JSON. To make it useful for a user, we need to visualize it. On Day 25, I added a "Spending Breakdown" chart to my Serverless Financial Agent.

My API returns a flat list of transactions: [{ category: "Food", amount: 10 }, { category: "Food", amount: 5 }]. But charting libraries expect grouped data: [{ name: "Food", value: 15 }].

I used a simple Javascript reduce/map logic inside my useEffect hook to transform the data before passing it to the charting library.

JavaScript
// The transformation logic
const categoryMap = {};
transactions.forEach(tx => {
const cat = tx.category;
categoryMap[cat] = (categoryMap[cat] || 0) + parseFloat(tx.amount);
});

I connected this to Recharts, a composable charting library for React. Now, my dashboard shows a live, color-coded breakdown of my spending habits directly from the bank API.