dot/rpc Implement RPC call state_getMetadata

dot/core/service.go

@@ -526,3 +526,8 @@ func (s *Service) HandleSubmittedExtrinsic(ext types.Extrinsic) error {
 	msg := &network.TransactionMessage{Extrinsics: []types.Extrinsic{ext}}
 	return s.safeMsgSend(msg)
 }
+
+//GetMetadata calls runtime Metadata_metadata function
+func (s *Service) GetMetadata() ([]byte, error) {
+	return s.rt.Exec(runtime.Metadata_metadata, []byte{})
+}

dot/rpc/modules/api.go

@@ -45,6 +45,7 @@ type CoreAPI interface {
 	GetRuntimeVersion() (*runtime.VersionAPI, error)
 	IsBabeAuthority() bool
 	HandleSubmittedExtrinsic(types.Extrinsic) error
+	GetMetadata() ([]byte, error)
 }
 
 // RPCAPI is the interface for methods related to RPC service

dot/rpc/modules/state.go

@@ -184,9 +184,13 @@ func (sm *StateModule) GetKeys(r *http.Request, req *StateStorageKeyRequest, res
 	// TODO implement change storage trie so that block hash parameter works (See issue #834)
 }
 
-// GetMetadata isn't implemented properly yet.
-func (sm *StateModule) GetMetadata(r *http.Request, req *StateRuntimeMetadataQuery, res *StateMetadataResponse) {
+// GetMetadata calls runtime Metadata_metadata function
+func (sm *StateModule) GetMetadata(r *http.Request, req *StateRuntimeMetadataQuery, res *string) error {
 	// TODO implement change storage trie so that block hash parameter works (See issue #834)
+	metadata, err := sm.coreAPI.GetMetadata()
+	// TODO use common.BytesToHex once PR #848 is merged
+	*res = "0x" + hex.EncodeToString(metadata)
+	return err
 }
 
 // GetRuntimeVersion Get the runtime version at a given block.

dot/rpc/modules/state_test.go

@@ -153,6 +153,18 @@ func TestStateModule_GetStorageSize_NotFound(t *testing.T) {
 	require.Equal(t, nil, res)
 }
 
+func TestStateModule_GetMetadata(t *testing.T) {
+	sm := setupStateModule(t)
+	var res string
+	err := sm.GetMetadata(nil, nil, &res)
+
+	// currently this is generating an error because runtime has not implemented Metadata_metadata yet
+	//  expect this to change when runtime changes
+	require.Equal(t, "0x", res)
+	require.EqualError(t, err, "Failed to call the `Metadata_metadata` exported function.")
+
+}
+
 func setupStateModule(t *testing.T) *StateModule {
 	// setup service
 	net := newNetworkService(t)

lib/runtime/runtime_test.go

@@ -65,3 +65,16 @@ func TestConcurrentRuntimeCalls(t *testing.T) {
 		_, _ = runtime.Exec(CoreVersion, []byte{})
 	}()
 }
+
+func TestRuntime_Exec_Metadata(t *testing.T) {
+	var expected []byte
+	runtime := NewTestRuntime(t, POLKADOT_RUNTIME_c768a7e4c70e)
+
+	ret, err := runtime.Exec(Metadata_metadata, []byte{})
+
+	// currently this is returning an error because runtime has not implemented Metadata_metadata yet
+	//  expect this to change when runtime changes
+	require.EqualError(t, err, "Failed to call the `Metadata_metadata` exported function.")
+	require.Equal(t, expected, ret)
+
+}

lib/runtime/types.go

@@ -84,6 +84,8 @@ var (
 	CoreInitializeBlock = "Core_initialize_block"
 	// CoreExecuteBlock is the runtime API call Core_execute_block
 	CoreExecuteBlock = "Core_execute_block"
+	// Metadata_metadata is the runtime API call Metadata_metadata
+	Metadata_metadata = "Metadata_metadata"
 	// TaggedTransactionQueueValidateTransaction is the runtime API call TaggedTransactionQueue_validate_transaction
 	TaggedTransactionQueueValidateTransaction = "TaggedTransactionQueue_validate_transaction"
 	// AuraAPIAuthorities is the runtime API call AuraApi_authorities