How to check authorization for a particular account in EOS smart contract?

Question

I want to write an EOS smart contract to manage users data. I need that only some admin account will able to add, update and delete users and the particular user can only update data. Can I check specific account authorization in a smart contract? And for update, can I check authorization of account either it should be admin or user? I am planning to set the primary key as each user account name. In this,

void insert(name user, std::string first_name, std::string last_name, std::string street, std::string city, std::string state) {
  require_auth( user );
}

It is checking authorization of a particular user, but I need it for an admin account who is going to do all transactions. Any suggestions will be appreciated.

Answer 1

You can search for an iterator with given key from multi_index first.

• iterator found: already created item, require_auth(user)
• iterator not found: not created item, require_auth(admin)

Permission check can be done in any step of your method. (Even you call require_auth() at the last time of your method, its failure reverts all changes made during that transaction)

--

You can separate insert/update or make them into one method like upsert.

void insert(name user, std::string first_name, ...) {
  require_auth("varshadmin"_n); // specific admin account name
  ...
}

void update(name user, ...) {
  check(has_auth(user) || has_auth("varshadmin"_n), "missing required authorization");
  ...
}

void upsert(name user, ...) {
  addressbook addr(_self, _self.value);
  auto itr = addr.find(user);
  if (itr == addr.end()) {
    // case 1: create new item
    require_auth("varshadmin"_n);
    addr.emplace(...);
  } else {
    // case 2: update existing utem
    check(has_auth(user) || has_auth("varshadmin"_n), "missing required authorization");
    addr.modify(itr, ...);
  }
}