graphql-pagination

graphql-pagination

Implements page-based pagination returning collection and pagination metadata. It works with kaminari or other pagination tools implementing similar methods.

Installation

Add graphql-pagination to your Gemfile, you can use kaminari-activerecord or kaminari-monogid to not implement page scope methods. Kaminari is not loaded by the gem, so you need to decide and load it on your own.

  gem 'graphql-pagination'
  gem 'kaminari-activerecord'

Usage example

Use collection_type instead of connection_type to define your type:

  field :fruits, Types::FruitType.collection_type, null: true do
    argument :page, Integer, required: false
    argument :limit, Integer, required: false
  end

  def fruits(page: nil, limit: nil)
    ::Fruit.page(page).per(limit)
  end

Value returned by query resolver must be a kaminari object or implements its page scope methods (current_page, limit_value, total_count, total_pages).

GraphQL query

{
  fruits(page: 2, limit: 2) {
    collection {
      id
      name
    }
    metadata {
      totalPages
      totalCount
      currentPage
      limitValue
    }
  }
}

{
  "data": {
    "checklists": {
      "collection": [
        {
          "id": "93938bb3-7a6c-4d35-9961-cbb2d4c9e9ac",
          "name": "Apple"
        },
        {
          "id": "b1ee93b2-579a-4107-8454-119bba5afb63",
          "name": "Mango"
        }
      ],
      "metadata": {
        "totalPages": 25,
        "totalCount": 50,
        "currentPage": 2,
        "limitValue": 2
      }
    }
  }
}

Custom Base

By default the resulting collection_type class is a direct descendant of graphql-ruby's GraphQL::Schema::Object, however you may require your own behaviours and properties on the collection class itself such as defining custom visibility.

This can be done by passing in your own custom class, to be inherited from:

class MyBaseType < GraphQL::Schema::Object
  def self.visible?(context)
    # ...
  end
end

field :fruits, Types::FruitType.collection_type(collection_base: MyBaseType)

Custom Metadata

By default, the following fields are present in the metadata block:

metadata {
  totalPages
  totalCount
  currentPage
  limitValue
}

These fields correspond to the GraphqlPagination::CollectionMetadataType used to provide the pagination information for the collection of data delivered. If you want to add more metadata fields to this block, you can do so by extending this CollectionMetadataType:

class MyMetadataType < GraphqlPagination::CollectionMetadataType
  field :custom_field, String, null: false
end

field :fruits, Types::FruitType.collection_type(metadata_type: MyMetadataType)

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/renofi/graphql-pagination. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.