Frontier EVM squid template

This is a template squid for indexing EVM contracts deployed to chains with Frontier EVM support (Moonbeam, Moonriver, Shiden, Astar). This template indexes token transfers on the Moonriver network and serves them via GraphQL API.

For more details, consult the Squid SDK docs

Dependencies: Node.js v16 or newer, Git, Docker.

Quickstart

# 0. Install @subsquid/cli a.k.a. the sqd command globally
npm i -g @subsquid/cli

# 1. Retrieve the template
sqd init my_squid_name -t frontier-evm
cd my_squid_name

# 2. Install dependencies
npm ci

# 3. Start a Postgres database container and detach
sqd up

# 4. Build the project
sqd build

# 5. Start both the squid processor and the GraphQL server
sqd run .

A GraphiQL playground will be available at localhost:4350/graphql.

You can also start squid services one by one:

sqd process
sqd serve

Dev flow

1. Define database schema

Start development by defining the schema of the target database via schema.graphql. Schema definition consists of regular graphql type declarations annotated with custom directives. Full description of schema.graphql dialect is available here.

2. Generate TypeORM classes

Mapping developers use TypeORM EntityManager to interact with target database during data processing. All necessary entity classes are generated by the squid framework from schema.graphql. This is done by running sqd codegen command.

3. Generate database migrations

All database changes are applied through migration files located at db/migrations. squid-typeorm-migration(1) tool provides several commands to drive the process.

## drop create the database
sqd down
sqd up

## replace any old schemas with a new one made from the entities
sqd migration:generate

See docs on database migrations for more details.

4. Import ABI contract and generate interfaces to decode events

It is necessary to import the respective ABI definition to decode EVM logs. For Moonsama transfers we use the standard ERC721 interface, see abi/erc721.json.

To generate a type-safe facade class to decode EVM logs, use squid-evm-typegen(1):

sqd typegen

See more details on the squid-evm-typegen doc page

Project conventions

Squid tools assume a certain project layout:

• All compiled js files must reside in lib and all TypeScript sources in src. The layout of lib must reflect src.
• All TypeORM classes must be exported by src/model/index.ts (lib/model module).
• Database schema must be defined in schema.graphql.
• Database migrations must reside in db/migrations and must be plain js files.
• sqd(1) and squid-*(1) executables consult .env file for environment variables.