Rails NoMethodError (undefined method `employee' for nil:NilClass)

Question

I got the following in the Rails log:

NoMethodError (undefined method `employee' for nil:NilClass):
  app/datatables/workorders4_datatable.rb:16:in `as_json'
  app/controllers/workorders_controller.rb:92:in `block (2 levels) in index8'
  app/controllers/workorders_controller.rb:90:in `index8'

This is the workorders4_datatable code:

class Workorders4Datatable

  delegate :params, :h, :link_to, :number_to_currency, to: :@view

  def initialize(view)
    @view = view
  end

  def mygroupsopenwos(employee)
    workorders.select("workorders.*").joins("left outer join empgroups ON empgroups.workgroup_id=workorders.workgroup_id").where("empgroups.employee_id = ?", employee).where("wostatus_id NOT IN (?)", [231, 230, 9263, 9264, 232] )
  end

  def as_json(options = {})
    {
        sEcho: params[:sEcho].to_i,
        iTotalRecords: mygroupsopenwos(User.current.employee.id).count,
        iTotalDisplayRecords: mygroupsopenwos(User.current.employee.id).total_entries,
        aaData: data
    }
  end

  private

  def data
    mygroupsopenwos(User.current.employee.id).map do |workorder|
      [
          link_to(workorder.wonum, workorder),
          h(workorder.parent.try(:wonum)),
          h(workorder.workgroup.try(:group_name)),
          h(workorder.employee.try(:last_name)),
          h(workorder.description),
          h(workorder.type.try(:typecode)),
          h(workorder.location.try(:name)),
          h(workorder.woasset.try(:assetnum)),
          h(workorder.wostatus.try(:statuscode)),
          h(workorder.priority)

      ]
    end
  end

  def workorders
    @workorders ||= fetch_workorders
  end

  def fetch_workorders
    workorders = Workorder.order("#{sort_column} #{sort_direction}")
    workorders = workorders.page(page).per_page(per_page)
    if params[:sSearch].present?
      workorders =   workorders.includes(:wostatus,:employee,:client,:type,:location).where("wonum ILIKE :search or workorders.description ILIKE :search or wostatuses.statuscode ILIKE :search or employees.last_name ILIKE :search or employees.first_name ILIKE :search or clients.client_name ILIKE :search or types.typecode ILIKE :search or locations.name ILIKE :search", search: "%#{params[:sSearch]}%")
    end
    workorders
  end

  def page
    params[:iDisplayStart].to_i/per_page + 1
  end

  def per_page
    params[:iDisplayLength].to_i > 0 ? params[:iDisplayLength].to_i : 10
  end

  def sort_column
    columns = %w[workorders.wonum workorders.parent_id workorders.workgroup_id workorders.employee_id workorders.description workorders.type_id workorders.location_id workorders.woasset_id workorders.wostatus_id workorders.priority]
    columns[params[:iSortCol_0].to_i]
 end

  def sort_direction
    params[:sSortDir_0] == "desc" ? "desc" : "asc"
  end
end

This line of code tries to get the employee:

              h(workorder.employee.try(:last_name)),

I'm using TRY - so why would I get an error?

Thanks for your help!!

Answer 1

def as_json(options = {})
  {
      sEcho: params[:sEcho].to_i,
      iTotalRecords: mygroupsopenwos(User.current.employee.id).count,
      iTotalDisplayRecords: mygroupsopenwos(User.current.employee.id).total_entries,
      aaData: data
  } if User.current
end

Answer 2

导致错误（16）的行中没有“ try”， User.current为nil。

Answer 3

Because you are using TRY in employee and the error is in workorder , I mean, workorder is nil.

Maybe, what you want is:

h(workorder.try(:employee).try(:last_name))