Contract won't keep index count inside index table

Question

Attempting to keep track of an index for future use as an index in another container.

        uint64_t namehash = ::eosio::string_to_uint64_t(my_name.c_str());
        auto name_iter = names.find(namehash);

        uint64_t next_idx = (names.begin() == names.end() ? 0 : (name_iter)->id + 1 );

        if( name_iter == names.end() ){
            names.emplace(_self, [&](struct nameList &a){
                a.id = next_idx;
                a.name = my_name;
                a.hash = namehash;
            });
            name_iter = names.find(namehash);
         }

First one registers 0 for the a.id but the next series of registers that register seems to always be 1.

Answer 1

You can get the size of the multi_index and add one to it.

auto size = std::count(names.cbegin(), names.cend());
a.id = size + 1;

Answer 2

You can use the available_primary_key() function that belongs to multi index arrays:

 a.id = names.available_primary_key()

This gets an incrementally larger primary key than the previous highest key