我正在尝试在 CanCanCan 中定义能力。
我无法弄清楚开始的语法。
我为我的角色使用角色模型，这些角色在我的 Profile.rb 中定义。Profile.rb 属于 User.rb。
我正在尝试检查用户是否具有角色：student。
当我尝试：
if {user_signed_in?, user.profile.has_role? :student}
我收到一个语法错误，上面写着：
syntax error, unexpected ',', expecting =>
if {user_signed_in?, user.profile.has_role? :student}
当我尝试：
if {user_signed_in? && user.profile.has_role? :student}
我收到一个语法错误，上面写着：
syntax error, unexpected tSYMBEG, expecting =>
if {user_signed_in? && user.profile.has_role? :student}
我还尝试用常规括号替换花括号并将它们完全删除。
当我尝试删除设计部分（user_signed_in）并使用下面评论中的建议时，我尝试：
if user.profile.has_role?(:student)
我得到这个错误：
undefined method `has_role?' for nil:NilClass
当我尝试：
if user.profile.has_role? :student
我收到此错误：
undefined method `has_role?' for nil:NilClass
当我尝试：
if user.profile.has_role?(student)
我收到此错误：
undefined local variable or method `student' for #<Ability:0x007fd034a78968>
我的 profile.rb 中定义了以下角色：
roles :admin, :manager, #
:student, :educator, :researcher, :ktp, :faculty_manager, :ip_asset_manager, # for universities
:sponsor, # for industry
:project_manager, :representative, # for both uni and industry
:grantor, :investor, :adviser, :innovation_consultant, :panel_member, # external
:participant, :guest # public
当我尝试：
can :crud, Profile, :user_id => user.id if user.profile.has_role? :student
我没有收到任何错误，但我对这种方法的问题是学生可以做很多事情（有 10 行权限，所以我需要将 if 语句单独添加到 10 个“can”语句中的每一个中，除非有一种方法可以在下一个“elsif”语句之前将 if 语句应用于所有行。
我的ability.rb的第一部分贴在下面（角色很多，能力也很多，所以我没有贴全）。
class Ability
include CanCan::Ability
def initialize(user)
alias_action :create, :read, :update, :destroy, :to => :crud
# Define abilities for the passed in user here. For example:
#
user ||= User.new # guest user (not logged in)
#users who are not signed in can create registration or login
# can read publicly available projects, programs and proposals
can :read, Project, {:active => true, :closed => false, :sweep => { :disclosure => { :allusers => true } } }
# {:active => true, :closed => false && :Project.sweep.disclosure.allusers => true}
# if user role is student
can :crud, Profile, :user_id => user.id if user.profile.has_role? :student #[for themselves]
can :read, ProjectInvitation, {:student_id => @current_user && :expiry_date_for_students_to_claim_project > Time.now}
# can read project invitations addressed to them
# can read projects to which they are invited whilst the invite is available to accept;
can :read, Project, {} #if invited to the project?
# and they can create responses to invitations to those projects
can :update, ProjectInvitation.student_accepted
# they can create questions on those projects before the invite expiry date;
can :read, ProjectQuestion, {} #if intvited
can [:create, :update, :destroy], ProjectQuestion #if they created the question
can :read, ProjectAnswer #if its on a project they can see
# they can update term sheets and template agreements for those projects
can [:read, :update], TermSheet #{where created for project in which they are participating}
can [:read, :update], ProjectAgreement #{where created for a project in which they are participating}
can [:read, :update], FinanceAgreement #{where created for a project in which they are participating}
can [:read, :update], Nda #{where created for a project in which they are participating}
can [:create, :update], Feedback #{where created for a project in which they are participating and the feedback is on other project team members and the project is completed}
elsif user.profile.has_role? :educator
当我尝试时（下面的建议）：
if user.try(:profile).present? && user.profile.has_role? :student
我收到此错误：
syntax error, unexpected tSYMBEG, expecting keyword_then or ';' or '\n'
...nt? && user.profile.has_role? :student
请问有人可以看到我做错了什么吗？