README.md
**NOTE: this project is looking for maintainers.** If you need caching to work for newer versions of graphql-ruby or for connection types, you may want to have a look at the [graphql-fragment_cache](https://github.com/DmitryTsepelev/graphql-ruby-fragment_cache) gem.
<img height=90 src=https://img.stackshare.io/misc/graphql-cache.png>
# GraphQL Cache
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A custom caching plugin for [graphql-ruby](https://github.com/rmosolgo/graphql-ruby)
## Goals
- Provide resolver-level caching for [GraphQL](https://graphql.org) APIs written in ruby
- Configurable to work with or without Rails
- [API Documentation](https://www.rubydoc.info/gems/graphql-cache)
## Why?
At [StackShare](https://stackshare.io) we've been rolling out [graphql-ruby](https://github.com/rmosolgo/graphql-ruby) for several of our new features and found ourselves in need of a caching solution. We could have simply used `Rails.cache` in our resolvers, but this creates very verbose types or resolver classes. It also means that each and every resolver must define it's own expiration and key. GraphQL Cache solves that problem by integrating caching functionality into the [graphql-ruby](https://github.com/rmosolgo/graphql-ruby) resolution process making caching transparent on most fields except for a metadata flag denoting the field as cached. More details on our motivation for creating this [here](https://stackshare.io/posts/introducing-graphql-cache).
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'graphql-cache'
```
And then execute:
```sh
$ bundle
```
Or install it yourself as:
```sh
$ gem install graphql-cache
```
## Setup
1. Use GraphQL Cache as a plugin in your schema.
```ruby
class MySchema < GraphQL::Schema
query Types::Query
use GraphQL::Cache
end
```
2. Add the custom caching field class to your base object class. This adds the `cache` metadata key when defining fields.
```ruby
module Types
class Base < GraphQL::Schema::Object
field_class GraphQL::Cache::Field
end
end
```
_Also note that if you want access to the `cache` keyword param in interface fields, the field_class directive must be added to your base interface module as well_
## Configuration
GraphQL Cache can be configured in an initializer:
```ruby
# config/initializers/graphql_cache.rb
GraphQL::Cache.configure do |config|
config.namespace = 'GraphQL::Cache' # Cache key prefix for keys generated by graphql-cache
config.cache = Rails.cache # The cache object to use for caching
config.logger = Rails.logger # Logger to receive cache-related log messages
config.expiry = 5400 # 90 minutes (in seconds)
end
```
## Usage
Any object, list, or connection field can be cached by simply adding `cache: true` to the field definition:
```ruby
field :calculated_field, Int, cache: true
```
### Custom Expirations
By default all keys will have an expiration of `GraphQL::Cache.expiry` which defaults to 90 minutes. If you want to set a field-specific expiration time pass a hash to the `cache` parameter like this:
```ruby
field :calculated_field, Int, cache: { expiry: 10800 } # expires key after 180 minutes
```
### Custom cache keys
GraphQL Cache generates a cache key using the context of a query during execution. A custom key can be included to implement versioned caching as well. By providing a `:key` value to the cache config hash on a field definition. For example, to use a custom method that returns the cache key for an object use:
```ruby
field :calculated_field, Int, cache: { key: :custom_cache_key }
```
With this configuration the cache key used for this resolved value will use the result of the method `custom_cache_key` called on the parent object.
### Forcing the cache
It is possible to force graphql-cache to resolve and write all cached fields to cache regardless of the presence of a given key in the cache store. This will effectively "renew" any existing cached expirations and warm any that don't exist. To use forced caching, add a value to `:force_cache` in the query context:
```ruby
MySchema.execute('{ company(id: 123) { cachedField }}', context: { force_cache: true })
```
This will resolve all cached fields using the field's resolver and write them to cache without first reading the value at their respective cache keys. This is useful for structured cache warming strategies where the cache expiration needs to be updated when a warming query is made.
## Development
After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run `bundle exec rake install`.
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/stackshareio/graphql-cache. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.
## License
The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
## Code of Conduct
Everyone interacting in the graphql-cache project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/stackshareio/graphql-cache/blob/master/CODE_OF_CONDUCT.md)..