Custom business logic with Hasura
whoami?
Agenda
- What is Hasura?
- Remote Schemas
- Event Triggers
- Hasura Actions
Introduction to Hasura
What is Hasura?
Instant GraphQL for all your data
Realtime GraphQL Engine
GraphQL Queries Compiler
users {
name
posts {
title
content
tags {
name
}
}
}SELECT
users.name
posts.title
posts.content
tags.name
FROM
users, posts, tags
WHERE
users.id = posts.author_id,
posts.id = tags.post_idMultiple databases
App
- Postgres
- Yugabyte
- Timescale
- MS SQL Server
- Big Query
Hasura Cloud
Authorization
Rest Endpoints
Business logic with Hasura
App
Remote Schemas
Unified GraphQL API
GraphQL Service
Data Triggers
APIs
Background jobs
GraphQL mutations
Event queue
Microservices
Serverless functions
Cron Triggers
Event queue
Microservices
Serverless functions
One-off Scheduled Triggers
Event queue
Microservices
Serverless functions
Actions
App
</>
GraphQL
query / mutation
POST endpoint
Actions
How does it work?
mutation createUser(user: {...}) {
...
}{
"input": {
"user": {...}
},
"session_variables": {...}
}1. GraphQL operation → Event payload
How does it work?
Async Mode: Event captured → Persisted → Event delivered
2. Delivering event to the webhook
{ ... } Event store
Event store
</>
How does it work?
2. Delivering event to the webhook
Sync Mode: Event captured → Event delivered
{ ... } </>
How does it work?
3. Receiving event response
Async Mode: event is put back in the event store
Event store
{ ... } Event store
Event store
</>
</>
How does it work?
3. Receiving event response
Sync mode: Hasura keeps the request open till receiving a response from the handler
{ ... } </>
</>
How does it work?
4. Getting results of the event handler
Async mode: Event response → GraphQL subscription
subscription {
createUserResult(actionId: "") {
userId
events {
name
date
}
}
}Event store
Postgres DB
How does it work?
4. Getting results of the event handler
Sync mode: Event response → GraphQL operation
mutation {
createUser(user: {...}) {
userId
events {
name
date
}
}
}DB
</>
Takeaways
Custom business logic with Hasura
By Aleksandra Sikora
