RPCConvertValues() call error

[Question] Hi, I’d like to call RPC programmatically, instead of using bitcoin-cli. when I call the function RPCConvertValues(), it always raise error RPCConvertValues() is defined here : https://github.com/bitcoin/bitcoin/blob/cab94cc07489f704c4b95171b23be0e8025df794/src/rpc/client.cpp#L221 test code are here : https://github.com/bitcoin/bitcoin/blob/46fc4d1a24c88e797d6080336e3828e45e39c3fd/src/test/rpc_tests.cpp#L319 https://github.com/bitcoin/bitcoin/blob/7967104aee055476107dc17265cefc4ae4e75378/src/bitcoin-cli.cpp#L293 https://github.com/bitcoin/bitcoin/blob/eb292af309aa57f3d7998b01307dd4cb91702908/src/qt/rpcconsole.cpp#L302 My test code : #include <iostream> #include <rpc/blockchain.cpp> #include <rpc/request.h> #include <rpc/client.h> #include <rpc/util.h> #include <univalue/include/univalue.h> #include <interfaces/node.h> namespace…

Provable/Oraclalize: How to get msg.sender in __callback

How do I get the msg.sender of the user who called randomNumber() in the __callback? pragma solidity ^0.5.11; import “github.com/provable-things/ethereum-api/provableAPI_0.4.25.sol”; contract ExampleContract is usingProvable {  function __callback(bytes32 myid, string result) {   if (msg.sender != provable_cbAddress()) revert();   // how do i get the address of the user who called “randomNumber”?  }  function randomNumber() public {   provable_query(“WolframAlpha”,…

If msg.value is specified in a call such as “msg.sender.call.value(msg.value)” then where is msg.value taken from, when this is from contract?

I mean in this case: function x(address receiver) { receiver.call.value(msg.value)(); } So receiver can be any address but msg.value cannot be controlled via argument? Does this mean that msg.value will always be zero or will it be taken from the msg.sender? Thanx!

Truffle Error: ContractName has no network configuration for its current network id (1575203139857)

Im doing the tutorial at https://github.com/ConsenSys-Academy/proof-of-existence-exercise and running into the following error: $ truffle console truffle(development)> var poe = await ProofOfExistence2.at(ProofOfExistence2.address) Thrown: Error: ProofOfExistence2 has no network configuration for its current network id (1575203139857). at evalmachine.<anonymous>:1:48 at Function.getter (C:\Users\mrleo\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\contract\lib\contract\constructorMethods.js:243:1) at Function.get (C:\Users\mrleo\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\contract\lib\contract\properties.js:129:1) at Function.getter (C:\Users\mrleo\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\contract\lib\contract\constructorMethods.js:246:1) at Function.network (C:\Users\mrleo\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\contract\lib\contract\properties.js:108:1) truffle(development)> truffle(development)>