/// <summary>
/// Gets multiple user profiles by their Ids.
/// </summary>
public override async Task <GetUserProfileResponse> GetUserProfile(GetUserProfileRequest request, ServerCallContext context)
{
var response = new GetUserProfileResponse();
if (request.UserIds == null || request.UserIds.Count == 0)
{
return(response);
}
// Since we're essentially doing a multi-get here, limit the number userIds (i.e. partition keys) to 20 in an attempt
// to enforce some performance sanity. Anything larger and we might want to consider a different data model that doesn't
// involve doing a multi-get
if (request.UserIds.Count > 20)
{
var status = new Status(StatusCode.InvalidArgument, "Cannot get more than 20 user profiles at once");
throw new RpcException(status);
}
// Do some LINQ queries in parallel
IEnumerable <Task <IEnumerable <LinqDtos.UserProfile> > > getProfilesTasks = request.UserIds.Select(uuid => _userProfileTable.Where(up => up.UserId == uuid.ToGuid()).ExecuteAsync());
IEnumerable <LinqDtos.UserProfile>[] profiles = await Task.WhenAll(getProfilesTasks).ConfigureAwait(false);
// Get first profile returned for each query if not null and add to response
response.Profiles.Add(profiles.Select(ps => ps.SingleOrDefault()).Where(p => p != null).Select(p => new UserProfile
{
UserId = p.UserId.ToUuid(),
Email = p.EmailAddress,
FirstName = p.FirstName,
LastName = p.LastName
}));
return(response);
}
/// <summary>
/// Gets multiple user profiles by their Ids.
/// </summary>
public override async Task <GetUserProfileResponse> GetUserProfile(GetUserProfileRequest request, ServerCallContext context)
{
var response = new GetUserProfileResponse();
if (request.UserIds == null || request.UserIds.Count == 0)
{
return(response);
}
// Since we're essentially doing a multi-get here, limit the number userIds (i.e. partition keys) to 20 in an attempt
// to enforce some performance sanity. Anything larger and we might want to consider a different data model that doesn't
// involve doing a multi-get
if (request.UserIds.Count > 20)
{
var status = new Status(StatusCode.InvalidArgument, "Cannot get more than 20 user profiles at once");
throw new RpcException(status);
}
// As an example, we'll do the multi-get at the CQL level using an IN() clause (i.e. let Cassandra handle it). For an example of
// doing it at the driver level, see the VideoCatalog's GetVideoPreviews method
// Build a parameterized CQL statement with an IN clause
var parameterList = string.Join(", ", Enumerable.Repeat("?", request.UserIds.Count));
var cql = $"SELECT userid, firstname, lastname, email FROM users WHERE userid IN ({parameterList})";
var statement = new SimpleStatement(cql, request.UserIds.Select(uuid => uuid.ToGuid()).Cast <object>().ToArray());
// Execute and map to UserProfile object
RowSet resultRows = await _session.ExecuteAsync(statement).ConfigureAwait(false);
response.Profiles.Add(resultRows.Select(MapRowToUserProfile));
return(response);
}