Skip to content

Guide.md

Latest commit

 

History

History
127 lines (98 loc) · 2.86 KB

Guide.md

File metadata and controls

127 lines (98 loc) · 2.86 KB

Guide to Get Started w/ Subgraphs

A subgraph extracts data from a blockchain, processing it and storing it so that it can be easily queried via GraphQL.

The subgraph definition consists of a few files:

  • subgraph.yaml: a YAML file containing the subgraph manifest,

  • schema.graphql: a GraphQL schema that defines what data is stored for your subgraph, and how to query it via GraphQL,

  • AssemblyScript Mappings: AssemblyScript code that translates from the event data to the entities defined in your schema (e.g. mapping.ts file).

Installation and Setup

Before starting installation, make sure that Node.js or Yarn is installed.

Install Graph CLI

Start by installing @graphprotocol/graph-cli:

yarn global add @graphprotocol/graph-cli

Initialize the Subgraph

graph init \
  --product subgraph-studio
  --from-contract <CONTRACT_ADDRESS> \
  [--network <ETHEREUM_NETWORK>] \
  [--abi <FILE>] \
  <SUBGRAPH_SLUG> [<DIRECTORY>]

Code

GraphQL Schema

type Gravatar @entity(immutable: true) {
  id: Bytes!
  owner: Bytes
  displayName: String
  imageUrl: String
  accepted: Boolean
}

Manifest

dataSources:
  - kind: ethereum/contract
    name: ExampleSource
    network: mainnet
    source:
      address: 'CONTRACT_ADDRESS'
      abi: ExampleContract
      startBlock: 6627917
    mapping:
      kind: ethereum/events
      apiVersion: 0.0.6
      language: wasm/assemblyscript
      file: ./src/mappings/mapping.ts
      entities:
        - User
      abis:
        - name: ExampleContract
          file: ./abis/ExampleContract.json
      eventHandlers:
        - event: NewGravatar(...)
          handler: handleNewGravatar
        - event: UpdatedGravatar(...)
          handler: handleUpdatedGravatar

Mapping

import { NewGravatar, UpdatedGravatar } from '../generated/Gravity/Gravity'
import { Gravatar } from '../generated/schema'

export function handleNewGravatar(event: NewGravatar): void {
  let gravatar = new Gravatar(event.params.id)
  gravatar.owner = event.params.owner
  gravatar.displayName = event.params.displayName
  gravatar.imageUrl = event.params.imageUrl
  gravatar.save()
}

export function handleUpdatedGravatar(event: UpdatedGravatar): void {
  let id = event.params.id
  let gravatar = Gravatar.load(id)
  if (gravatar == null) {
    gravatar = new Gravatar(id)
  }
  gravatar.owner = event.params.owner
  gravatar.displayName = event.params.displayName
  gravatar.imageUrl = event.params.imageUrl
  gravatar.save()
}

This basic subgraph tracks the following two events of Gravatar contract:

  • NewGravatar(),
  • UpdatedGravatar().

Code Generation

yarn codegen

Build

yarn build

Deploy

yarn deploy

You just deployed your subgraph! Now, you can make GraphQL queries on the interface of The Graph.