How to get transaction history on a particular key in Hyperledger Fabric?

Question

I have a Hyperledger Fabric network with multiple peers with corresponding StateDB (CouchDB) and I have given CORE_LEDGER_HISTORY_ENABLEHISTORYDATABASE=true in all peer configuration under docker compose file. The idea that I shall be able to retrieve the update history of a record basis the key. The key here is a trade number and whenever any attribute of Trade gets updated, I do see update happening in CouchDB as I see increase in revision value. Now, in my chaincode function, have added below snippet of code (sample code for now)

_, args := stub.GetFunctionAndParameters()

tradeNumber := args[1]

historyIer, err := stub.GetHistoryForKey(tradeNumber)

if err != nil {
    fmt.Println(err.Error())
    return shim.Error(err.Error())
}

if historyIer.HasNext() {
    modification, err := historyIer.Next()
    if err != nil {
        fmt.Println(err.Error())
        return shim.Error(err.Error())
}
fmt.Println("Returning information about", string(modification.Value))

} return shim.Success(nil)

However, everytime I check chaincode container, it prints only the last value of Trade than the number of updates it has gone through, can anybody please let me know what wrong am I doing here?

Answer 1

Well, the problem that using the history iterator only once instead of actually iterating over it.

Instead of:

if historyIer.HasNext() {
    modification, err := historyIer.Next()
    if err != nil {
        fmt.Println(err.Error())
        return shim.Error(err.Error())
    }
    fmt.Println("Returning information about", string(modification.Value))
}

You need to do:

for historyIer.HasNext() {
    modification, err := historyIer.Next()
    if err != nil {
        fmt.Println(err.Error())
        return shim.Error(err.Error())
    }
    fmt.Println("Returning information about", string(modification.Value))
}

which is going to iterate over all key updates and print values.