public async Task <bool> AddProjectAttendant(PersonInProjectParameterDto parameters)
        {
            if (await projectRepository.GetSingleByCondition(x => x.ProjectId == parameters.ProjectId) == null)
            {
                return(false);
            }

            bool notFound = false;

            foreach (var personId in parameters.AttendantIds)
            {
                var newAttendant = await personRepository.GetSingleByCondition(x => x.PersonId == personId);

                if (newAttendant == null)
                {
                    notFound = true;
                    break;
                }
            }

            if (notFound)
            {
                return(false);
            }

            foreach (var attendantId in parameters.AttendantIds)
            {
                PersonInProject personInProject = new PersonInProject {
                    PersonId = attendantId, ProjectId = parameters.ProjectId
                };
                await personInProjectRepository.Create(personInProject);
            }

            return(await personInProjectRepository.SaveChanges());
        }