How to read a state after writing it into a chaincode

Question

I have setup the Fabric as per the instruction using docker and everything works fine. I have a chaincode which stores a value in the world state which I can read afterwards using a query method. When I submit multiple separate requests within a short period of time to store different data in the world state, I need to read th data submitted previously within each request. However, I am unable to read the most recently submitted data.

So I am wondering if there is any way to read the previous data just after storing the subsequent data.

Answer 1

Data that is 'written' in chaincode is not yet committed to the database, it is only a proposal to write something to the database at that point. So, waiting a few seconds in the chaincode would not be sufficient. Only committed data is read back in chaincode. Therefore after you make an update in chaincode and get the proposal response, you must submit the transaction to ordering. Only then can the data be read back in chaincode.

However, If you must read the data that you just wrote within the same chaincode function, then you will need to keep a map of the data that has been written and retrieve the value from the map rather than from the committed database.

Hope this helps :)