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---
layout: guide
doc_stub: false
search: true
section: Subscriptions
title: Subscription Type
desc: The root type for subscriptions
index: 1
---
`Subscription` is the entry point for all subscriptions in a GraphQL system. Each field corresponds to an event which may be subscribed to:
```graphql
type Subscription {
# Triggered whenever a post is added
postWasPublished: Post
# Triggered whenever a comment is added;
# to watch a certain post, provide a `postId`
commentWasPublished(postId: ID): Comment
}
```
This type is the root for `subscription` operations, for example:
```graphql
subscription {
postWasPublished {
# This data will be delivered whenever `postWasPublished`
# is triggered by the server:
title
author {
name
}
}
}
```
To add subscriptions to your system, define an `ObjectType` named `Subscription`:
```ruby
# app/graphql/types/subscription_type.rb
class Types::SubscriptionType < GraphQL::Schema::Object
field :post_was_published, subscription: Subscriptions::PostWasPublished
# ...
end
```
Then, add it as the subscription root with `subscription(...)`:
```ruby
# app/graphql/my_schema.rb
class MySchema < GraphQL::Schema
query(Types::QueryType)
# ...
# Add Subscription to
subscription(Types::SubscriptionType)
end
```
See {% internal_link "Implementing Subscriptions","subscriptions/implementation" %} for more about actually delivering updates.
See {% internal_link "Subscription Classes", "subscriptions/subscription_classes" %} for more about implementing subscription root fields.
|
