Inline action for transferring tokens

Question

I am trying to transfer some tokens as part of my contract action, but I get an error:

ACTION maincontract::sendtoken(const name sender, const name receiver) {
  action(
    permission_level{ get_self(), "active"_n },
      "eosio.token"_n, 
      "transfer"_n,
      std::make_tuple(sender, receiver, "120000 MYTOKEN", "memo")
  ).send();
}

the error I get in EOS Studio is:

assertion failure with message: read
{
  "code": 500,
  "message": "Internal Service Error",
  "error": {
    "code": 3050003,
    "name": "eosio_assert_message_exception",
    "what": "eosio_assert_message assertion failure",
    "details": [
      {
        "message": "assertion failure with message: read",
        "file": "wasm_interface.cpp",
        "line_number": 1075,
        "method": "eosio_assert"
      },
      {
        "message": "pending console output: ",
        "file": "apply_context.cpp",
        "line_number": 113,
        "method": "exec_one"

UPDATE: it seems that the contract cannot transfer money on behalf of the user. I cannot expect all the users to give permission to the contract. So, how can I resolve this?

Answer 1

how did you create the MYTOKEN token? can you please explain the procedure you used to create this token?

Answer 2

I think these threads will answer your question in detail (see the other questions linked in the initial question as well):

Transfer tokens inside a smart contract from an account to another account

here you get more detailed explanations as well: https://github.com/EOSIO/eos/issues/3847