Add private data go application by twoGiants · Pull Request #1264 · hyperledger/fabric-samples

twoGiants · 2024-10-29T09:01:07Z

Private Data Go Application

This PR contains an implementation of a go application using Hyperledger Fabrics private data feature as described in the main Hyperledger Fabric documentation here.

It follows the exact same procedure and uses the same naming as the private data typescript sample here.

The implementation uses the Gateway SDK and the issue reference is here in the Fabric Gateway SDK repository.

Summary

created project directory, app.go and connect.go files
reused the logic for connect.go from the events application
added second organization setup
implemented private data transaction
updated README.md with the command to run the go application
updated script which runs the application in the Github Actions workflow
fixed typos and punctuation in the private data typescript application
manual tests

bestbeforetoday

Thank you for a great contribution! A few suggested changes in-line. Also there is a logic error that definitely needs to be corrected.

The issue seems to be the JSON mapping with property names appearing with initial capital letters (as they appear in the Go structs) whereas the contract is working with initial lower case letters. The JSON mappings should probably be explicitly specified throughout the code to be safe.

bestbeforetoday · 2024-10-29T17:08:05Z

@@ -0,0 +1,358 @@
+/*
+Copyright 2022 IBM All Rights Reserved.


Since this is new code, I would use 2024 as the year

Thx! Corrected.

bestbeforetoday · 2024-10-29T17:11:41Z

+	fmt.Println("~~~~~~~~~~~~~~~~ As Org1 Client ~~~~~~~~~~~~~~~~")
+
+	// Create new assets on the ledger.
+	createAssets(*contractOrg1)


I would avoid dereferencing the Contract pointer here. Instead, pass the pointer with the createAssets function taking a *client.Contract argument

Suggested change

createAssets(*contractOrg1)

createAssets(contractOrg1)

Thx! Corrected.

bestbeforetoday · 2024-10-29T17:12:06Z

+	createAssets(*contractOrg1)
+
+	// Read asset from the Org1's private data collection with ID in the given range.
+	getAssetByRange(*contractOrg1)


Avoid dereferencing and pass the pointer

Suggested change

getAssetByRange(*contractOrg1)

getAssetByRange(contractOrg1)

bestbeforetoday · 2024-10-29T17:16:11Z

+	err = transferAsset(*contractOrg1, assetID1)
+	if err == nil {
+		doFail("TransferAsset transaction succeeded when it was expected to fail")
+	}


You could condense this slightly but either form is valid so your choice. I would suggest passing the pointer rather than copying the value though:

Suggested change

err = transferAsset(*contractOrg1, assetID1)

if err == nil {

doFail("TransferAsset transaction succeeded when it was expected to fail")

}

if err := transferAsset(contractOrg1, assetID1); err == nil {

doFail("TransferAsset transaction succeeded when it was expected to fail")

}

Can't use the condensed form because I need to print the error after the if statement. Removed dereference.

bestbeforetoday · 2024-10-29T17:16:32Z

+	fmt.Println("\n~~~~~~~~~~~~~~~~ As Org2 Client ~~~~~~~~~~~~~~~~")
+
+	// Read the asset by ID.
+	readAssetByID(*contractOrg2, assetID1)


Avoid dereference

Suggested change

readAssetByID(*contractOrg2, assetID1)

readAssetByID(contractOrg2, assetID1)

bestbeforetoday · 2024-10-29T18:22:50Z

+	fmt.Printf("*** Result: %s\n", result)
+}
+
+func transferAsset(contract client.Contract, assetID string) (err error) {


Suggested change

func transferAsset(contract client.Contract, assetID string) (err error) {

func transferAsset(contract *client.Contract, assetID string) (err error) {

bestbeforetoday · 2024-10-29T18:23:00Z

+	return
+}
+
+func deleteAsset(contract client.Contract, assetID string) (err error) {


Suggested change

func deleteAsset(contract client.Contract, assetID string) (err error) {

func deleteAsset(contract *client.Contract, assetID string) (err error) {

bestbeforetoday · 2024-10-29T18:23:09Z

+	return
+}
+
+func purgeAsset(contract client.Contract, assetID string) (err error) {


Suggested change

func purgeAsset(contract client.Contract, assetID string) (err error) {

func purgeAsset(contract *client.Contract, assetID string) (err error) {

bestbeforetoday · 2024-10-29T18:23:18Z

+	return
+}
+
+func readAssetPrivateDetails(contract client.Contract, assetID, collectionName string) bool {


Suggested change

func readAssetPrivateDetails(contract client.Contract, assetID, collectionName string) bool {

func readAssetPrivateDetails(contract *client.Contract, assetID, collectionName string) bool {

bestbeforetoday · 2024-10-29T18:25:36Z

+	dataForAgreement := struct {
+		AssetID        string
+		AppraisedValue int
+	}{assetID, 100}


This seems to be the cause of the transfer failure. The agreement is hashed and is sensitive to the capitalization of the JSON property names, which the contract treats with an initial lower-case letter

Suggested change

dataForAgreement := struct {

AssetID string

AppraisedValue int

}{assetID, 100}

dataForAgreement := struct {

AssetID string `json:"assetID"`

AppraisedValue int `json:"appraisedValue"`

}{assetID, 100}

bestbeforetoday · 2024-10-29T21:06:10Z

+func transientData(key string, value any) map[string][]byte {
+	valueAsBytes, err := json.Marshal(&value)
+	if err != nil {
+		panic(err)
+	}
+
+	return map[string][]byte{key: valueAsBytes}
+}


This definitely does the job for this use-case, where the application only creates transient maps with a single key/value. I wonder if (as an example) it might be worth using a more generic alternative, something like:

func marshal(value any) []byte { result, err := json.Marshal(value) if err != nil { panic(err) } return result }

This would be used as follows:

client.WithTransient(map[string][]byte{ "asset_properties": marshal(asset1Data), })

Just an idea to consider.

Yes, good point and good idea. I would add a type alias to the map so it looks a bit nicer:

type transient = map[string][]byte // ... client.WithTransient(transient{ "asset_properties": marshal(asset1Data), }),

wdyt?

bestbeforetoday · 2024-10-29T21:16:37Z

+	result := formatJSON(resultBytes)
+	if result == "" {
+		fmt.Println("*** No result")
+		return false
+	}


If the transaction result is empty, I think trying to parse it as JSON will fail. Instead if checking the the JSON being empty, I think you will need to check for empty resultBytes:

Suggested change

result := formatJSON(resultBytes)

if result == "" {

fmt.Println("*** No result")

return false

}

if len(resultBytes) == 0 {

fmt.Println("*** No result")

return false

}

result := formatJSON(resultBytes)

Yes, you're right. Thank you for pointing out. Fixed it in all places.

twoGiants · 2024-10-30T14:51:11Z

Thank you for the review. I fixed the issue and added all the changes. You can take another look.

Created project directory, app.go and connect.go files. Reused the logic for connect.go from the events application and added second organization setup. Implemented private data transaction example in go as described in the main documentation in "Tutorials/Using Private Data in Fabric". Updated README.md with the command to run the go application and the script which runs the application in the Github Actions workflow. Fixed typos and punctuation in the private data typescript application. Signed-off-by: Stanislav Jakuschevskij <stas@two-giants.com>

bestbeforetoday

Thank you for the updates. This looks good to me!

denyeart

Nice job, thanks!

twoGiants requested a review from a team as a code owner October 29, 2024 09:01

twoGiants mentioned this pull request Oct 29, 2024

Migrate fabric-samples to use Gateway SDKs hyperledger/fabric-gateway#190

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bestbeforetoday requested changes Oct 29, 2024

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bestbeforetoday reviewed Oct 29, 2024

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twoGiants force-pushed the private-data-go branch 3 times, most recently from 205bf39 to ddef44a Compare October 30, 2024 14:48

twoGiants requested a review from bestbeforetoday October 30, 2024 14:51

twoGiants force-pushed the private-data-go branch from ddef44a to e6aca84 Compare October 30, 2024 14:54

bestbeforetoday approved these changes Oct 31, 2024

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denyeart approved these changes Oct 31, 2024

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denyeart merged commit 9b199d4 into hyperledger:main Oct 31, 2024

	readAssetByID(*contractOrg2, assetID1)
	readAssetByID(contractOrg2, assetID1)

	func transferAsset(contract client.Contract, assetID string) (err error) {
	func transferAsset(contract *client.Contract, assetID string) (err error) {

	func deleteAsset(contract client.Contract, assetID string) (err error) {
	func deleteAsset(contract *client.Contract, assetID string) (err error) {

	func purgeAsset(contract client.Contract, assetID string) (err error) {
	func purgeAsset(contract *client.Contract, assetID string) (err error) {

	func readAssetPrivateDetails(contract client.Contract, assetID, collectionName string) bool {
	func readAssetPrivateDetails(contract *client.Contract, assetID, collectionName string) bool {

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Private Data Go Application

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