Ruby on Rails：未定义的方法`[]'为nil：NilClass [duplicate]

可能重复：Ruby on Rails：params为零 . 未定义的方法`[]'为nil：NilClass

我有一个搜索功能，正在搜索某些东西，但我无法进入搜索页面，因为我收到此错误 .

NoMethodError in ProjectsController#search

undefined method `[]' for nil:NilClass

在我的项目控制器中，第26行：

tech_ids = params["technols"]["id"].reject(&:blank?).

这显然与我试图删除空白这一事实有关 .

这是我的搜索操作：

def search
  tech_ids = params["technols"]["id"].reject(&:blank?)

  @search = params[:client], params[:industry], params[:role], tech_ids, params[:business_div], params[:project_owner],  params[:status], params[:start_date_dd], params[:start_date_A], params[:start_date_B],  params[:keywords]

  @project_search = Project.search(*@search).order(sort_column + ' ' + sort_direction).paginated_for_index(per_page, page)

  @search_performed = !@search.reject! { |c| c.blank? }.empty? 
  @project = Project.new(params[:project])
  @all_technols = Technol.all
  @project_technol = @project.projecttechnols.build

  respond_to do |format|
    format.html # search.html.erb
    format.json { render :json => @project }
  end
end

这是我的项目模型：

class Project < ActiveRecord::Base
  attr_accessible  :edited_first_name, :edited_last_name, :first_name, :last_name, :business_div, :client, :customer_benifits, :edited_date, :end_date, :entry_date,  :financials, :industry, :keywords, :lessons_learned, :project_name, :project_owner, :role, :start_date, :status, :summary, :tech

  validates_presence_of :business_div, :client, :customer_benifits, :end_date, :exception_pm, :financials, :industry, :keywords, :lessons_learned, :project_name, :project_owner, :role, :start_date, :status, :summary#, :tech

  has_many :projecttechnols
  has_many :technols, :through => :projecttechnols


  def self.like(text); "%#{text}%"; end

  def self.search(search_client, search_industry, search_role, search_techs_ids, search_business_div, search_project_owner, search_status, search_start_date_dd, search_start_date_A, search_start_date_B,  search_keywords)
    # start with a scoped query, to apply more scopes on it afterwards
    _projects = Project.scoped 
    # then, for each of the parameters, apply the scope only if present
    if search_client.present?
      _projects = _projects.where ['client LIKE ?', like(search_client)] 
    end

    if search_industry.present?
      projects = _projects.where ['industry LIKE ?', like(search_industry)]
    end

    if search_role.present?
      _projects = _projects.where ['role LIKE ?', like(search_role)]
    end

    if search_techs_ids.present?
      _projects = _projects.joins(:technols).where("technols.id" => search_techs_ids)
    end

    if search_business_div.present?
      _projects = _projects.where ['business_div LIKE ?', like(search_business_div)]
    end 

    if search_project_owner.present?
      _projects = _projects.where ['project_owner LIKE ?', like(search_project_owner)]
    end

    if search_exception_pm.present?
      _projects = _projects.where ['exception_pm LIKE ?', like(search_exception_pm)]
    end

    if search_status.present?
      _projects = _projects.where ['status LIKE ?', like(search_status)]
    end

    todays_date = DateTime.now.to_date

    if !search_start_date_A.blank? or !search_start_date_B.blank?
      search_start_date_A = Date.parse(search_start_date_A).strftime("%Y-%m-%d")
      search_start_date_B = Date.parse(search_start_date_B).strftime("%Y-%m-%d")
      todays_date = nil
      search_start_date_dd = nil
    end

    if search_start_date_dd.blank?
      todays_date = nil
    end

    if search_start_date_A.present? or search_start_date_B.present?
      _projects = _projects.where [' DATE(start_date) BETWEEN ? AND ?', search_start_date_A, search_start_date_B]
    end

    if search_start_date_dd.present?
      _projects = _projects.where ['DATE(start_date) BETWEEN ? AND ?', search_start_date_dd, todays_date]
    end

    if search_keywords.present?
      _projects = _projects.where ['keywords LIKE ?', like(search_keywords)]
    end

    _projects
  end


  def self.paginated_for_index(projects_per_page, current_page)
    paginate(:per_page => projects_per_page, :page => current_page)
  end
end

希望这是一个简单的解决方案