Why is input number non-existent in bitcoin API?
That is how it works, you need to look up the previous transaction where that output exists in order to get the value. The equivalent call using bitcoin-cli is:

$ bitcoin-cli getrawtransaction 9de8923855b2c56bc903c39418298fa8c185e5feb99cb32bfa31b9d06700ced8 2


then you can find the vout with index 1.