升级到Rails 5.1.7后出现错误ArgumentError：无效参数：nil

Question

升级到Rails 5.1.7之后，出现错误ArgumentError：无效参数：nil。

测试：

describe 'default_for scope' do
    it 'joins intel_tags' do
      scope = IntelTagging.default_for('something')
      expect(scope.joins_values).to include(:intel_tag)
    end

    it 'uses IntelTag.default_for' do
      expect(IntelTag).to receive(:default_for).with('something')
      IntelTagging.default_for('something')
    end
  end

型号：

class IntelTagging < ApplicationRecord
...
belongs_to :intel_tag, inverse_of: :intel_taggings, optional: true
accepts_nested_attributes_for :intel_tag

validates_presence_of :intel_tag

scope :default_for, ->(type) {
    joins(:intel_tag).merge(IntelTag.default_for(type))
  }

  scope :key, ->(key) { joins(:intel_tag).merge(IntelTag.key(key)) }
...
end

class IntelTag < ApplicationRecord
...
has_many :intel_taggings, inverse_of: :intel_tag, dependent: :destroy

scope :default_for, ->(string) { where(arel_table[:default_for].matches("%#{string}%")) }
...
end

[我发现在导轨5中它有所改变->将ArgumentError或nil传递到false时提高Relation#merge。这些不是在关系中合并的有效值，因此应尽早警告用户。

我做了以下非常难看的事情：

scope :default_for, ->(type) {
    joins_intel_tag = joins(:intel_tag)
    joins_intel_tag.merge(IntelTag.default_for(type)) if joins_intel_tag.present?
  }

但仍然有错误

 (IntelTag(id: integer, managed: boolean, default_for: text, unmanaged_name: string, name_en: string, name_fr: string, name_it: string, name_de: string, deleted_at: datetime, created_at: datetime, updated_at: datetime, key: string) (class)).default_for("something")
           expected: 1 time with arguments: ("something")
           received: 0 times

Answer 1

当前进行了以下操作以通过测试，但正在寻找更好的解决方案：

scope :default_for, ->(type) {
    joins(:intel_tag).merge(IntelTag.default_for(type)) unless IntelTag.default_for(type).nil?
  }

  scope :key, ->(key) {
    IntelTag.key(key).nil? ? joins(:intel_tag) : joins(:intel_tag).merge(IntelTag.key(key))
  }