Array type is not supported by MySQL

[Phil Nash]

Hi, I'm new to Elixir so trying to add small features to applications right now. Please excuse me if this is totally dumb, but I've spent a while trying to debug and I'm lost.

I started to work on rrrene/elixirstatus-web#13 which was to add pagination using Scrivener. Here is what I've done: rrrene/elixirstatus-web@master...philnash:pagination. I hoped that it would be mostly as simple as adding Scrivener and changing the call to Repo.all to Repo.paginate in the PostingsController. However, I get the error Array type is not supported by MySQL. The full stack trace is below:

[error] #PID<0.490.0> running ElixirStatus.Endpoint terminated
Server: localhost:4000 (http)
Request: GET /postings
** (exit) an exception was raised:
    ** (ArgumentError) Array type is not supported by MySQL
        (ecto) lib/ecto/adapters/mysql/connection.ex:352: Ecto.Adapters.MySQL.Connection.expr/2
        (elixir) lib/enum.ex:1008: anonymous fn/4 in Enum.map_join/3
        (elixir) lib/enum.ex:1261: Enum."-reduce/3-lists^foldl/2-0-"/3
        (elixir) lib/enum.ex:1007: Enum.map_join/3
        (ecto) lib/ecto/adapters/mysql/connection.ex:347: Ecto.Adapters.MySQL.Connection.expr/2
        (elixir) lib/enum.ex:1008: anonymous fn/4 in Enum.map_join/3
        (elixir) lib/enum.ex:1261: Enum."-reduce/3-lists^foldl/2-0-"/3
        (elixir) lib/enum.ex:1007: Enum.map_join/3

I can understand MySQL not being able to do some things, but this seems like a simple use case and I can't tell where or how I am trying to use the Array type.

Any help would be gladly received. Thanks.

[Drew Olson]

Thanks for reporting this. My only suspicion at this point would be the way we're performing the count[1]. I'll try to look into it more later today.

[1] - https://github.com/drewolson/scrivener/blob/master/lib/scrivener.ex#L153

[Drew Olson]

@philnash on closer inspection, it appears Ecto may not support the array type for MySQL[1]. Perhaps @josevalim or @ericmj would have a better idea.

[1] - https://github.com/elixir-lang/ecto/blob/master/lib/ecto/adapters/mysql/connection.ex#L342-L344

[José Valim]

Yes, MySQL does not support arrays but count should not be the one triggering it. @drewolson can you please run your tests with MySQL too (maybe add it to travis) and let us know which query exactly is failing? Thanks everyone!

I have opened an issue in ecto to improve the error message.

[Phil Nash]

I have an idea! To the fork-mobile!

[José Valim]

"fork-mobile" - I am cracking up

[Drew Olson]

Best issue thread ever. @josevalim I'll attempt to get tests running on MySQL in Travis today.