Rails 4 将为祖先分页

Question

我在 Rails 4 项目中使用 will_paginate gem。当我查看调用paginate()返回的对象的祖先时，我以为我会在祖先列表中看到与will_paginate相关的东西，例如，可能是WillPaginate::Collection，但我没有看到这样的东西。如果 will_paginate 没有出现在祖先树中的任何位置，我很困惑我的对象如何获得像 current_page 和 total_pages 这样的方法。

例如：

location = Location.first
reviews = location.location_reviews.paginate(page: 1, per_page: 5)

reviews.next_page # => 2
reviews.total_pages # => 16
reviews.total_entires # => 80

但是，reviews.ancestors 的输出是：

[LocationReview(id: integer, title: string), LocationReview::GeneratedAssociationMethods, #<#<Class:0x007fd6623bec38>:0x007fd6623beda0>, ActiveRecord::Base, GlobalID::Identification, ActiveRecord::Store, ActiveRecord::Serialization, ActiveModel::Serializers::Xml, ActiveModel::Serializers::JSON, ActiveModel::Serialization, ActiveRecord::Reflection, ActiveRecord::NoTouching, ActiveRecord::Transactions, ActiveRecord::Aggregations, ActiveRecord::NestedAttributes, ActiveRecord::AutosaveAssociation, ActiveModel::SecurePassword, ActiveRecord::Associations, ActiveRecord::Timestamp, ActiveModel::Validations::Callbacks, ActiveRecord::Callbacks, ActiveRecord::AttributeMethods::Serialization, ActiveRecord::AttributeMethods::Dirty, ActiveModel::Dirty, ActiveRecord::AttributeMethods::TimeZoneConversion, ActiveRecord::AttributeMethods::PrimaryKey, ActiveRecord::AttributeMethods::Query, ActiveRecord::AttributeMethods::BeforeTypeCast, ActiveRecord::AttributeMethods::Write, ActiveRecord::AttributeMethods::Read, ActiveRecord::Base::GeneratedAssociationMethods, #<#<Class:0x007fd661d14e28>:0x007fd661d14ef0>, ActiveRecord::AttributeMethods, ActiveModel::AttributeMethods, ActiveRecord::Locking::Pessimistic, ActiveRecord::Locking::Optimistic, ActiveRecord::AttributeDecorators, ActiveRecord::Attributes, ActiveRecord::CounterCache, ActiveRecord::Validations, ActiveModel::Validations::HelperMethods, ActiveSupport::Callbacks, ActiveModel::Validations, ActiveRecord::Integration, ActiveModel::Conversion, ActiveRecord::AttributeAssignment, ActiveModel::ForbiddenAttributesProtection, ActiveRecord::Sanitization, ActiveRecord::Scoping::Named, ActiveRecord::Scoping::Default, ActiveRecord::Scoping, ActiveRecord::Inheritance, ActiveRecord::ModelSchema, ActiveRecord::ReadonlyAttributes, ActiveRecord::Persistence, ActiveRecord::Core, Object, ActiveSupport::Dependencies::Loadable, PP::ObjectMixin, JSON::Ext::Generator::GeneratorMethods::Object, Kernel, BasicObject]

为什么这个输出中没有与 will_paginate 相关的类？

Answer 1

您正在调用location.location_reviews 上的.paginate 方法，这是这里的集合。根据paginate方法的源代码的this line和this line，似乎paginate方法在应用选项（例如per_page）后返回原始集合。

所以，我认为在您的情况下，location.location_reviews.paginate(page: 1, per_page: 5) 将返回 location.location_reviews.class 类的对象是正常行为。

paginate 将返回 https://github.com/mislav/will_paginate/blob/74a6cd0197072903cd8b83744133744ff4b4c046/lib/will_paginate/array.rb#L30 将返回的任何内容，pager.replace 方法在这里定义：https://github.com/mislav/will_paginate/blob/74a6cd0197072903cd8b83744133744ff4b4c046/lib/will_paginate/collection.rb#L112-L134 它返回原始集合类型对象。这证明你看到的行为是正确的。