Allow users to withdraw their tokens

Question

In my contract I have an action which is supposed to allow users to collect the tokens they have accumulated. To do this I use:

void transfer_token(account_name receiver, asset quantity, std::string memo) {

    action(
            permission_level{_self, N(active)},
            N(eosio.token),
            N(transfer),
            std::make_tuple(_self, receiver, quantity, memo)
    ).send();
}

But for this to work I have to use the following command for every user:

cleos set account permission <contract> active '{"threshold": 1,"keys": [{"key": <public_key>,"weight": 1}],"accounts": [{"permission":{"actor": <user>,"permission":"active"},"weight":1}]}' owner -p <contract>

My question is:

How can I, using scatter and eosjs, setup the authorization for a user to call an action that transfers tokens from the contract to himself?

edit: I am using scatter on my client, and it has been setup properly, I can use it to transfer tokens to the contract.

edit: Here's the output of using the client to call the action that makes the contract transfer tokens to the user.

{
  "code": 500,
  "message": "Internal Service Error",
  "error": {
    "code": 3090003,
    "name": "unsatisfied_authorization",
    "what": "Provided keys, permissions, and delays do not satisfy declared authorizations",
    "details": [
      {
        "message": "transaction declares authority '{\"actor\":\"testacccpico\",\"permission\":\"active\"}', but does not have signatures for it under a provided delay of 0 ms, provided permissions [{\"actor\":\"testacccpico\",\"permission\":\"eosio.code\"}], provided keys [], and a delay max limit of 3888000000 ms",
        "file": "authorization_manager.cpp",
        "line_number": 413,
        "method": "check_authorization"
      },
      {
        "message": "pending console output: ",
        "file": "apply_context.cpp",
        "line_number": 61,
        "method": "exec_one"
      }
    ]
  }
}

Answer 1

Assuming you have setup the scatter and eosjs for your front. if not go here After that you need to set permissions, Using two functions like this:

async getScatter(nextProps) {
    const scatter = nextProps.scatterObj;
    const { accounts } = await scatter.getIdentity({
      accounts: [config.EOS_CONFIG.network]
    });
    return accounts;
  }

  setNewPermissions = accountName => {
    this.props.eosObj
      .getAccount(accountName)
      .then(account => {
        let newPerms = this.updatePermissions(
          JSON.parse(JSON.stringify(account.permissions))
        );
        console.log(newPerms);

        this.props.eosObj.transaction(tr => {
          for (const perm of newPerms) {
            if (perm.perm_name === "active") {
              tr.updateauth({
                account: accountName,
                permission: perm.perm_name,
                parent: perm.parent,
                auth: perm.required_auth
              });
            }
          }
        });
      })
      .catch(e => {
        console.log(e);
      });
  };
  updatePermissions = permissions => {
    for (let perm of permissions) {
      if (perm.perm_name === "active") {
        let newPerm = {
          permission: {
            actor: config.EOS_CONFIG.contractSender,
            permission: "eosio.code"
          },
          weight: 1
        };
        if (!this.isObjPresentInArray(newPerm, perm.required_auth.accounts))
          perm.required_auth.accounts.push(newPerm);
      }
    }
    return permissions;
  };

You also need to import the private key for the account to whom you providing the permission. Hope this will work for you.