Fabric-sdk-go client.Query returns error: failed to create transactor: Channel_Cfg_Cache - cache is closed - hyperledger-fabric-sdk-go

Question

I am trying to make a simple demo using the fabric-sdk-go. I wonder anybod know why the code below ("client.Query") returns the error "failed to create transactor: Channel_Cfg_Cache - cache is closed"?
func initSdkClient() (*channel.Client){
sdk, err := fabsdk.New(config.FromFile("config.yaml"))
if err != nil {
logger.Fatalf("Failed to create new SDK: %s", err)
}
defer sdk.Close()
//prepare channel client context using client context
clientChannelContext := sdk.ChannelContext(channelID, fabsdk.WithUser("User1"), fabsdk.WithOrg(orgName))
// Channel client is used to query and execute transactions (Org1 is default org)
client, err := channel.New(clientChannelContext)
if err != nil {
logger.Fatalf("Failed to create new channel client: %s", err)
}
return client
}
func queryCC(client *channel.Client, targetEndpoints ...string) []byte {
response, err := client.Query(channel.Request{ChaincodeID: ccID, Fcn: "invoke", Args: defaultQueryArgs},
channel.WithRetry(retry.DefaultChannelOpts),
channel.WithTargetEndpoints(targetEndpoints...),
)
if err != nil {
***logger.Fatalf("Failed to query funds: %s", err)*** // error: failed to create transactor: Channel_Cfg_Cache - cache is closed
}
return response.Payload
}
func main() {
client := initSdkClient()
existingValue := queryCC(client)
logger.Info(existingValue)
logger.Info("hello, world\n")
}

Answer 1

Probably because you're closing the SDK instance at the end of initSdkClient function. Rather close the SDK at the end of main function.
Do something like
type Setup struct {
sdk *fabsdk.FabricSDK
client *channel.Client
}
func (setup *Setup) initSdkClient() *channel.Client {
sdk, err := fabsdk.New(config.FromFile("config.yaml"))
if err != nil {
fmt.Errorf("Failed to create new SDK: %s", err)
}
setup.sdk = sdk
//prepare channel client context using client context
clientChannelContext := setup.sdk.ChannelContext(channelID, fabsdk.WithUser("User1"), fabsdk.WithOrg(orgName))
// Channel client is used to query and execute transactions (Org1 is default org)
client, err := channel.New(clientChannelContext)
if err != nil {
fmt.Errorf("Failed to create new channel client: %s", err)
}
setup.client = client
return client
}
func (setup *Setup) queryCC(client *channel.Client, targetEndpoints ...string) []byte {
response, err := setup.client.Query(channel.Request{ChaincodeID: ccID, Fcn: "invoke", Args: defaultQueryArgs},
channel.WithRetry(retry.DefaultChannelOpts),
channel.WithTargetEndpoints(targetEndpoints...),
)
if err != nil {
fmt.Errorf("Failed to query funds: %s", err)
}
return response.Payload
}
func main() {
var setup Setup
client := setup.initSdkClient()
defer setup.sdk.Close()
existingValue := setup.queryCC(client)
}