CODEWITHSUNDEEP
ruby-on-rails-3datamapper
Jenny Blunt
Jenny Blunt

Reputation: 1596

Rails 3 and DataMapper: group by wrong number of arguments

I'm having issues using the groupby and distinct queries in RoR3.

If I using this in my controller, all is well:

@radgroupchecks = Radgroupcheck.find_by_sql("select * from radgroupcheck group by groupname")

But I want to do in rails. I've tried:

@radgroupchecks = Radgroupcheck.select("DISTINCT(groupname)").all

But that gives me an error: wrong number of arguments(1 for 0)

What am I doing wrong?!

Upvotes: 1

Views: 1124

Answers (1)

Behrang Saeedzadeh
Behrang Saeedzadeh

Reputation: 47913

You need to use the group method for grouping in ActiveRecord. I think what you want is this:

Radgroupcheck.all.group('groupname')

Check out this link for more information.

BTW, it's better (more conventional, but not necessary) to use camel casing for your classes in Ruby (e.g. RedGroupCheck).

UPDATE: DataMapper

I haven't used DataMapper before, but looks like you need to write something like this:

Redgroupcheck.all(:fields => [:groupname], :unique => true)

This might help. (Search for "group" on that page).

Upvotes: 1

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