"warning: multiple values for a block parameter (2 for 1)" in Ruby

Question

I have a function users_by_role

and it returns data in following format,

[
  [#<Role id: 1, name: "Developer">,[#<User id:1, name: "Abc">,#<User id:2, name: "xyz">]]
  [#<Role id: 2, name: "Tester">,[#<User id:11, name: "Abcd">,#<User id:12, name: "wxyz">]]
]

Now, I want to select users for given Role/s

I am using,

project.users_by_role.select{|o| o.first.name == "Developer"}

where project is a Project object

All good, code returns me the data but along with which I get following warning

warning: multiple values for a block parameter (2 for 1)

Also I am looking for optimized and shorter way of doing this

Complete code snippet looks like:

project.users_by_role.select{|o| o.first.name == "Developer" }.collect{|e| e.last.map{|f| [f.id,f.firstname + ' ' + f.lastname]}}.flatten(1).uniq

By above code I want to get all the user names for a given role.

Cœur · Accepted Answer · 2018-01-22 06:38:47Z

1

The warning: it says that you expected 1 argt, and it passes 2. That's because it "expands the argts" to take account of the 2 elements array.

project.users_by_role.select {|role, users| role.name == "Developer"}

And for a better way:

If the role is uniq within the #users_by_role data returned, you can avoid a map.

users = project.users_by_role.select {|role, users| role.name == "Developer"}.first.last
users_for_select = users.map {|user| [user.id, "#{user.firstname} #{user.lastname}"] }

edited Jan 22, 2018 at 6:38

Cœur

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answered May 30, 2012 at 7:50

Maxime

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4 Comments

hitesh israni Over a year ago

looks like i misunderstood the data returned by users_by_role. yes it should be project.users_by_role.select {|role, users|}

hitesh israni Over a year ago

and regarding second answer, project.users_by_role.select {|role, users| role.name == "Developer" or role.name == Tester"}.first.last. wont give desired result. so this is what i am using, project.users_by_role.select {|role, users| role.name == "Developer" or role.name == "Reporter"}.collect{|role,users| users.map{|u| [u.id,u.firstname]}}.flatten(1).uniq

hitesh israni Over a year ago

many thnx for figuring out the mistake. also would you like to comment on better way?

Maxime Over a year ago

I assumed you wanted to retrieve only one role, so your way is fine.

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