多索引表 创建singleton实例

Posted 2021-10-28 thefist11

singleton_example.hpp

#include <eosio/eosio.hpp>
#include <eosio/singleton.hpp>
using namespace eosio;

class [[eosio::contract]] singleton_example : public contract {
   public:
      using contract::contract;
      singleton_example( name receiver, name code, datastream<const char*> ds ) :
         contract(receiver, code, ds),
         singleton_instance(receiver, receiver.value)  {}

      [[eosio::action]]
      void set( name user, uint64_t value );

      [[eosio::action]]
      void get( );

      struct [[eosio::table]] testtable {
         name primary_value;
         uint64_t secondary_value;
         uint64_t primary_key() const { return primary_value.value; }
      } testtablerow;

      using singleton_type = eosio::singleton<"testtable"_n, testtable>;
      singleton_type singleton_instance;

      using set_action = action_wrapper<"set"_n, &singleton_example::set>;
      using get_action = action_wrapper<"get"_n, &singleton_example::get>;
};

singleton_example.cpp

#include <singleton_example.hpp>

[[eosio::action]] void singleton_example::set( name user, uint64_t value ) {
   auto entry_stored = singleton_instance.get_or_create(user, testtablerow);
   entry_stored.primary_value = user;
   entry_stored.secondary_value = value;
   singleton_instance.set(entry_stored, user);
}

[[eosio::action]] void singleton_example::get( ) {
   if (singleton_instance.exists())
      eosio::print(
         "Value stored for: ", 
         name{singleton_instance.get().primary_value.value},
         " is ",
         singleton_instance.get().secondary_value,
         "\\n");
   else
      eosio::print("Singleton is empty\\n");
}