Add GetFile API in app and plugin (#9820)

plugin/api.go

@@ -336,6 +336,11 @@ type API interface {
 	// Minimum server version: 5.3
 	GetFileInfo(fileId string) (*model.FileInfo, *model.AppError)
 
+	// GetFile gets content of a file by it's ID
+	//
+	// Minimum Server version: 5.8
+	GetFile(fileId string) ([]byte, *model.AppError)
+
 	// GetFileLink gets the public link to a file by fileId.
 	//
 	// Minimum server version: 5.6

plugin/client_rpc_generated.go

@@ -2837,6 +2837,35 @@ func (s *apiRPCServer) GetFileInfo(args *Z_GetFileInfoArgs, returns *Z_GetFileIn
 	return nil
 }
 
+type Z_GetFileArgs struct {
+	A string
+}
+
+type Z_GetFileReturns struct {
+	A []byte
+	B *model.AppError
+}
+
+func (g *apiRPCClient) GetFile(fileId string) ([]byte, *model.AppError) {
+	_args := &Z_GetFileArgs{fileId}
+	_returns := &Z_GetFileReturns{}
+	if err := g.client.Call("Plugin.GetFile", _args, _returns); err != nil {
+		log.Printf("RPC call to GetFile API failed: %s", err.Error())
+	}
+	return _returns.A, _returns.B
+}
+
+func (s *apiRPCServer) GetFile(args *Z_GetFileArgs, returns *Z_GetFileReturns) error {
+	if hook, ok := s.impl.(interface {
+		GetFile(fileId string) ([]byte, *model.AppError)
+	}); ok {
+		returns.A, returns.B = hook.GetFile(args.A)
+	} else {
+		return encodableError(fmt.Errorf("API GetFile called but not implemented."))
+	}
+	return nil
+}
+
 type Z_GetFileLinkArgs struct {
 	A string
 }

plugin/plugintest/api.go

@@ -713,6 +713,31 @@ func (_m *API) GetEmojiList(sortBy string, page int, perPage int) ([]*model.Emoj
 	return r0, r1
 }
 
+// GetFile provides a mock function with given fields: fileId
+func (_m *API) GetFile(fileId string) ([]byte, *model.AppError) {
+	ret := _m.Called(fileId)
+
+	var r0 []byte
+	if rf, ok := ret.Get(0).(func(string) []byte); ok {
+		r0 = rf(fileId)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).([]byte)
+		}
+	}
+
+	var r1 *model.AppError
+	if rf, ok := ret.Get(1).(func(string) *model.AppError); ok {
+		r1 = rf(fileId)
+	} else {
+		if ret.Get(1) != nil {
+			r1 = ret.Get(1).(*model.AppError)
+		}
+	}
+
+	return r0, r1
+}
+
 // GetFileInfo provides a mock function with given fields: fileId
 func (_m *API) GetFileInfo(fileId string) (*model.FileInfo, *model.AppError) {
 	ret := _m.Called(fileId)