Question

i am using the Booksleeve hash api for Redis. I am doing the following:

  CurrentConnection.Hashes.Set(0, "item:1", "priority", task.priority.ToString());

  var taskResult = CurrentConnection.Hashes.GetString(0, "item:1", "priority");

  taskResult.Wait();

  var priority = Int32.Parse(taskResult.Result)

However i am getting an Aggregate exception:
“ERR Operation against a key holding the wrong kind of value”

I am not sure what i am doing wrong here (except of blocking the task :)).

Note: CurrentConnection is an instance of BookSleeve.RedisConnection

Please help!

Thanks

Answer 1

That is not a Booksleeve issue – it is a redis error; in fact, the full error message you should be seeing is:

Redis server: ERR Operation against a key holding the wrong kind of value

(where I try to make it clear that this error has come from redis, not Booksleeve)

As for what causes this: each key in redis has a designated type; string, hash, list, etc. You cannot use hash operations on something that is not a hash.

My guess, then, is that “item:1” already exists, but as something other than a hash. I have unit tests that confirm this from Booksleeve (i.e. with/without a pre-existing non-hash value).

You can investigate this in redis using redis-cli or any other client (telnet works, at a push), with the command:

type item:1

(thanks @Sripathi)