Is there a reason I can't see/store a SHA256 in a Hyperledger Fabric worldstate?

I have been working on testing hyperledger fabric to store details on a selection of files and folders including sha256 keys to track updates made to a file. I have installed the test network, I am able to get the network running correctly and have installed and defined the chaincode to work. Everything is working perfectly, except when I query the assets the only field missing is the sha256 key.

Is there a reason for this?

This is how the ledger should be initialised:

// InitLedger adds a base set of assets to the ledger func (s *SmartContract) InitLedger(ctx contractapi.TransactionContextInterface) error { assets := []Asset{ {ID: "asset1", sha256: "3654dda35f2604fe43af8b49fae361b0ab77850fc4b9b2d21f098bed8bfdf376", Size: 56, ModifiedOn: "06.04.2022 09:29"}, {ID: "asset2", sha256: "fe8979c8c7b6f69b393ff1bbd688d3cafa3fd3e8efc1955682cc685517bd64b7", Size: 9756, ModifiedOn: "28.05.2020 10:26"}, {ID: "asset3", sha256: "c023e9f6c1fb3d0ba9894123e0c58c46039863dea617e9007569f76014334206", Size: 5992, ModifiedOn: "20.03.2022 08:53"}, {ID: "asset4", sha256: "5f87db405f88f6788710a6f21c4dd74221716b4832a17d3cbd4701741c716a9b", Size: 45336, ModifiedOn: "21.09.2016 11:21"}, {ID: "asset5", sha256: "367c38d5833e63e19a2053c2787b9913ed45e406d947a55fc08b21d03c60a9d7", Size: 108, ModifiedOn: "13.08.2013 10:40"}, {ID: "asset6", sha256: "d1652041e169ddfe0ee32cd0f8b4ef6f968dbd2dd119a3769dd44081661bf202", Size: 5308, ModifiedOn: "21.02.2019 17:00"}, {ID: "asset7", sha256: "2f9684e36bace94d4791160a31e0595e4cae7a9f17003d460f01c7e1ed1e8b04", Size: 8704, ModifiedOn: "12.04.2022 17:02"}, {ID: "asset8", sha256: "702b9d6ddd7d850ca7ae06d9521ef5400ea5d8a2e6ffa75737560ef54b3a1ba1", Size: 13436, ModifiedOn: "27.02.2022 09:22"}, {ID: "asset9", sha256: "a81f09ae679dbf4c597060d6de14283b69c7c1a0c0fbc6e484c5762d0c19ab26", Size: 159732, ModifiedOn: "27.04.2022 13:35"}, {ID: "asset10", sha256: "6e166d4f7c464cff392f3d4e3e13bd780243a9793d19b95a1eb1df896ab9162a", Size: 322120, ModifiedOn: "25.05.2022 09:41"}, }

This is the result of a query:

peer chaincode query -C mychannel -n basic -c '{"Args":["GetAllAssets"]}' [{"ID":"asset1","ModifiedOn":"06.04.2022 09:29","Size":56},{"ID":"asset10","ModifiedOn":"25.05.2022 09:41","Size":322120},{"ID":"asset2","ModifiedOn":"28.05.2020 10:26","Size":9756},{"ID":"asset3","ModifiedOn":"20.03.2022 08:53","Size":5992},{"ID":"asset4","ModifiedOn":"21.09.2016 11:21","Size":45336},{"ID":"asset5","ModifiedOn":"13.08.2013 10:40","Size":108}, {"ID":"asset6","ModifiedOn":"21.02.2019 17:00","Size":5308},{"ID":"asset7","ModifiedOn":"12.04.2022 17:02","Size":8704},{"ID":"asset8","ModifiedOn":"27.02.2022 09:22","Size":13436},{"ID":"asset9","ModifiedOn":"27.04.2022 13:35","Size":159732}]

The sha256 is just missing. Any help on this would be greatly appreciated.

You are marshalling the asset to JSON to store in the ledger. The Go JSON marshaller only includes exported fields. For example:

type Asset struct {
    sha256 string `json:"privateSHA256"`
    SHA256 string `json:"publicSHA256"`
}

func main() {
asset := &Asset{
    sha256: "privateSHA256Value",
    SHA256: "publicSHA256Value",
}

    assetJSON, err := json.MarshalIndent(asset, "", "    ")
    if err != nil {
        panic(err)
    }

    fmt.Printf("Asset: %#v\n", asset)
    fmt.Printf("JSON: %s\n", assetJSON)
}

Produces the following output:

Asset: &main.Asset{sha256:"privateSHA256Value", SHA256:"publicSHA256Value"}
JSON: {
    "publicSHA256": "publicSHA256Value"
}