Go Node Interaction
The following snippet shows how to query the state using gRPC inside a Go program. The idea is to create a gRPC connection, and use the Protobuf-generated client code to query the gRPC server.
import (
"context"
"fmt"
"google.golang.org/grpc"
sdk "github.com/cosmos/cosmos-sdk/types"
"github.com/cosmos/cosmos-sdk/types/tx"
)
func queryState() error {
myAddress, err := sdk.AccAddressFromBech32("inj...")
if err != nil {
return err
}
// Create a connection to the gRPC server.
grpcConn := grpc.Dial(
"127.0.0.1:9090", // your gRPC server address.
grpc.WithInsecure(), // The SDK doesn't support any transport security mechanism.
)
defer grpcConn.Close()
// This creates a gRPC client to query the x/bank service.
bankClient := banktypes.NewQueryClient(grpcConn)
bankRes, err := bankClient.Balance(
context.Background(),
&banktypes.QueryBalanceRequest{Address: myAddress, Denom: "inj"},
)
if err != nil {
return err
}
fmt.Println(bankRes.GetBalance()) // Prints the account balance
return nil
}
Query for historical state using Go
Querying for historical blocks is done by adding the block height metadata in the gRPC request.
import (
"context"
"fmt"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
grpctypes "github.com/cosmos/cosmos-sdk/types/grpc"
"github.com/cosmos/cosmos-sdk/types/tx"
)
func queryState() error {
// --snip--
var header metadata.MD
bankRes, err = bankClient.Balance(
metadata.AppendToOutgoingContext(context.Background(), grpctypes.GRPCBlockHeightHeader, "12"), // Add metadata to request
&banktypes.QueryBalanceRequest{Address: myAddress, Denom: denom},
grpc.Header(&header), // Retrieve header from response
)
if err != nil {
return err
}
blockHeight = header.Get(grpctypes.GRPCBlockHeightHeader)
fmt.Println(blockHeight) // Prints the block height (12)
return nil
}
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