Hyperledger chaincode does not get current user metadata - blockchain

Question

Currently I'm working with Hyperledger chaincode and trying to get at least any info regarding current user who invokes/queries chaincode. For some reason chaincode example asset_management.go results in an error "ERRO 031 Got error: Invalid admin certificate. Empty." I have security.enabled and security.privacy set to true and Membership services running. I've enrolled "admin".
Here are the lines in the code where it happens
// Set the admin
// The metadata will contain the certificate of the administrator
adminCert, err := stub.GetCallerMetadata()
if err != nil {
myLogger.Debug("Failed getting metadata")
return nil, errors.New("Failed getting metadata.")
}
if len(adminCert) == 0 {
myLogger.Debug("Invalid admin certificate. Empty.")
return nil, errors.New("Invalid admin certificate. Empty.")
}
Do you have any ideas how to make the chaincode return any data for stub.GetCallerMetadata() ?

Answer 1

"Metadata" should be provided in your deploy command, an example of "deploy" for asset_management_with_roles:
curl -XPOST -d ‘{“jsonrpc": "2.0", "method": "deploy", "params": {"type": 1,"chaincodeID": {"path": "github.com/hyperledger/fabric/examples/chaincode/go/asset_management_with_roles","language": "GOLANG"}, "ctorMsg": { "args": ["init"] }, "metadata":[97, 115, 115, 105, 103, 110, 101, 114] ,"secureContext": "assigner"} ,"id": 0}' http://localhost:7050/chaincode
In this command "metadata" contains utf-8 encoded string “assigner”. This string will be saved in a ledger and only user with such role will be able to execute “assign” function in smart contract.
"asset_management" example expects that you will provide certificate in metadata field. In order to obtain certificate you can use step 9 described in related question: How is running the asset_management.go different from running a simple chaincode like chaincode_example02.go