Prefixes.md

Prefixes

You may notice the use of types.FreeFlixNFTPrefix and types.CoCoNFTPrefix. These are defined in a file called ./nfts/internal/types/key.go and help us keep our Keeper organized. The Keeper is just a key-value store. That means that similar to an Object in javascript, all values are referenced under a key. To access a value, you need to know the key under which it is stored. This is a bit like a unique identifier (UID).

When storing a TweetNFT we use the key of the PrimartNFTID as a unique ID if it is from FreeFlix chain, otherwise we use the key SecondaryNFTID if it is from CoCo chain. However since we are storing it in the same location, we may want to distinguish between the types of nftIDs we use as keys. We can do this by adding prefixes to the nftIDs that allow us to recognize which is which. For FreeFlixNFT we add the prefix ffmttweetnft and for CoCoNFT we add the prefix cocotweetnft. You should add these to your key.go file so it looks as follows:

package types

import (
    "strconv"
    
    sdk "github.com/cosmos/cosmos-sdk/types"
)

const (
    ModuleName   = "nfts"
    RouterKey    = ModuleName
    QuerierRoute = ModuleName
    StoreKey     = ModuleName
    
    FreeFlixNFTPrefix = "ffmttweetnft"
    CoCoNFTPrefix     = "cocotweetnft"
    
    FreeFlixContext = "freeflix"
    CoCoContext     = "coco"
)

var (
    GlobalTweetCountPrefix = []byte{0x01}
    TweetAccountPrefix     = []byte{0x02}
    TweetNFTPrefix         = []byte{0x03}
)

func GetGlobalTweetCountKey() []byte {
    return GlobalTweetCountPrefix
}

func GetTweetNFTKey(id []byte) []byte {
    return append(TweetNFTPrefix, id...)
}

func GetTweetsCountOfAddressKey(addr []byte) []byte {
    return append(TweetAccountPrefix, addr...)
}

func GetPrimaryNFTID(count uint64) string {
    return FreeFlixNFTPrefix + strconv.Itoa(int(count))
}

func GetContextOfCurrentChain() string {
    config := sdk.GetConfig()
    return config.GetBech32AccountAddrPrefix()
}

func GetSecondaryNFTID(count uint64) string {
    return CoCoNFTPrefix + strconv.Itoa(int(count))
}