[EOS源码分析]7.EOS智能合约开发实践之合约调用合约(inline action)

首先，目前dawn-4.1, dawn-4.2使用inline action是会报如下错误

transaction declares authority '{"actor":"hello.code","permission":"active"}', but does not have signatures for it under a provided delay of 0 ms

这个问题是4.0以后inline action的权限发生变化导致的。这个改动在eos官网的#3013这个issue讨论BM有提到过

[EOS源码分析]7.EOS智能合约开发实践之合约调用合约(inline action)

核心是为智能合约账号添加eosio.code permission,比如hello.code调用hello.target智能合约，需要添加如下permission

cleos set account permission args.user active '{"threshold": 1,"keys": [{"key":"EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV", "weight":1}],"accounts": [{"permission":{"actor":"hello.code","permission":"eosio.code"},"weight":1}]}' owner -p [email protected]

代码

新建两个contract: hello.code和hello.target

hello.target代码如下

hello.code的代码：

class hello : public eosio::contract {
  public:
    using contract::contract;
    /// @abi action 
    void hi( account_name from, account_name to) {
        require_auth(from);
        print( "Hello, from:", name{from}, ", to:", name{to});

        action(
            //这里{to, active}必须授权给{_self, eosio.code}
            permission_level{to, N(active)},
            //调用 hello.target合约 的'callme' action
            N(hello.target), N(callme),
            std::make_tuple(to)
         ).send();
    }
};

核心就是上面的红色字体的内容action(xx).send()，具体参数的含义是：

Action(permssion_level, other_contract_account_name, method, args)

所以:

action(permission_level{to, N(active)},
           N(hello.target), N(callme), 
           std::make_tuple(to)
).send();

这个等价于如下命令

$cleos push action hello.target callme '["to"]' -p to

编译

请参考我的博文【EOS编写HelloWorld智能合约】

测试

$cleos create account eosio hello.code $KEY_PUB_1 $KEY_PUB_1
$cleos set contract hello.code ./hello -p hello.code
$cleos create account eosio args.user $KEY_PUB_2 $KEY_PUB_2
$cleos create account eosio hello.target $KEY_PUB_3 $KEY_PUB_3
$cleos create account eosio args.user1 $KEY_PUB_4 $KEY_PUB_4
$cleos set contract hello.target ./hello.target -p hello.target
$cleos set account permission args.user1 active '{"threshold": 1,"keys": [],"accounts": [{"permission":{"actor":"hello.code","permission":"eosio.code"},"weight":1}]}' owner -p [email protected]
$cleos push action hello.code hi '["args.user", "args.user1"]' -p args.user