多索引表 定义secondary index

Posted 2021-10-28 thefist11

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

// multi index example contract class
class [[eosio::contract]] multi_index_example : public contract {
   public:
      using contract::contract;

      // contract class constructor
      multi_index_example( name receiver, name code, datastream<const char*> ds ) :
         // contract base class contructor
         contract(receiver, code, ds),
         // instantiate multi index instance as data member (find it defined below)
         testtab(receiver, receiver.value) 
         { }

      struct [[eosio::table]] test_table {
        // this field stores a name for each row of the multi index table
        name test_primary;
        name secondary;
        // additional data stored in table row
        uint64_t datum;
        // mandatory definition for primary key getter
        uint64_t primary_key( ) const { return test_primary.value; }
        uint64_t by_secondary( ) const { return secondary.value; }
      };

      // the multi index type definition, for ease of use a type alias `test_tables` is defined, 
      // based on the multi_index template type, parametarized with a random name, the 
      // test_table data structure, and the secondary index
      typedef eosio::multi_index<"testtaba"_n, test_table, eosio::indexed_by<"secid"_n, eosio::const_mem_fun<test_table, uint64_t, &test_table::by_secondary>>> test_tables;

      // the multi index table instance declared as a data member of type test_tables
      test_tables testtab;

      [[eosio::action]] void set(name user);
      [[eosio::action]] void print(name user);

      using set_action = action_wrapper<"set"_n, &multi_index_example::set>;
      using print_action = action_wrapper<"print"_n, &multi_index_example::print>;
};