Checking Empty or nil in ruby on rails

Checking for array is empty in ruby
@user = User.where(:name => "chinna").all
<%unless @user.empty?%>
<%@user.each do |u| %>
<%=u.email%>
<%=u.dob%>
<%end%>
Ruby on rails undefined method `name' for nil:NilClass
<%@user.name unless @user.name.nil? %>
##Cheking for params[:name] is present or not?
@user = User.where(:id => params[:id]).first
if params[:name].present?
@user.update_attributes(:name => params[:name])
end

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