cm-graphql

CmGraphql

This should help you to install graphql and setup the basics on any new rails application.

• Adds Graphql gem and runs the graphql installer
• Copies the grapqhl schema template which has the rescue block configured.
• Certain files like grapqhl query, input and exceptions are inside the gem, which makes the listing of records easier.

Install

Add the gem to the Gemfile

gem 'cm-graphql'

Setup

If this is the first time graphql is getting added to the project, run the following generator

rails g cm_graphql:add_graphql

This will run the graphql generator graphql:install and copy the graphql schema template.

Generator

Another generator to help you get started with a basic list endpoint is

rails g cm_graphql:list_api model_name
rails g cm_graphql:list_api course


# Sample grapqhl request

query {
	courses(paging: {
		pageNo: 1
		perPage: 100
	}) {
		paging {
			currentPage
			totalPages
			totalCount
		}	
		data {
			id
      name
		}
	}
}

This will add the necessary files to the application.

• course_list_type
• course_type
• course_query

Mount the engine at

mount CmGraphql::Engine => "/cm-graphql"

And you are done, you can test out the pagination.

Explaination on how this works.

• Kaminari Gem has page and per methods. These methods are used to set the page no and records per page of a model.
• The paging Input type in app/graphql/types/inputs/base/paging.rb exposes a interface to the frontend where the frontend can enter page no and records per page.
• The query uses a list method on the model. This method is inherited by the model from the paginator concern.
• We apply the kaminari method in the list method to apply pagination to the model.
• The paginator then calls the filtered_list model to arrange the model data and paging data in a representable way. This helps us make sure all the pagination follow the same pattern for data representation.
• The paging_type in app/graphql/types/objects/base/paging_type.rb is used to represent the paging data to the frontend.
• The pagination and model data is represented with object type in app/graphql/types/objects/example_list_type.rb.
• And we have successfully applied pagination to our graphql project.