Cách truy cập dữ liệu lịch sử từ hợp đồng

If you need the data in real time you can simply just call the contract read function. If you need historical data and need to call the read function though at a time in the past that is where you will need to either be indexing the emitted event data or using the call handler. You can use Subgraph Studio directly and no need to run your own graph node since you are indexing Matic.