Using HashMap in Solana Rust Contract

Question

I have found that it is not possible to use HashMap, but BtreeStorage is possible. I have already tried to use those. But I am getting errors. I was trying to use this: https://github.com/hashblock/solana-cli-program-template/blob/main/program/src/account_state.rs#L62

Answer 1

Both pack and unpack are provided by the Pack trait. You'll have to first bring the trait into scope with use solana_program::program_pack::Pack;