EVM squid template (FireSquid edition)

This is a FireSquid version of the sample squid showcasing EVM log indexing for substrate chains with a Frontier EVM pallete, like Astar or Moonbeam. This template indexes Moonsama token transfers over the Moonriver network and serves them via graphql API.

Quickstart

# 1. Install dependencies
npm ci

# 2. Compile typescript files
make build

# 3. Start target Postgres database and detach
make up

# 4. Start the processor
make process

# 5. The command above will block the terminal
#    being busy with fetching the chain data, 
#    transforming and storing it in the target database.
#
#    To start the graphql server open the separate terminal
#    and run
make serve

Migrate from v5 to FireSquid

To migrate old (v5) Squids to FireSquid, follow the Migration Guide

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 npx sqd codegen command.

3. Generate database migration

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

# Connect to database, analyze its state and generate migration to match the target schema.
# The target schema is derived from entity classes generated earlier.
# Don't forget to compile your entity classes beforehand!
npx squid-typeorm-migration generate

# Create template file for custom database changes
npx squid-typeorm-migration create

# Apply database migrations from `db/migrations`
npx squid-typeorm-migration apply

# Revert the last performed migration
npx squid-typeorm-migration revert   

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 src/abis/ERC721.json.

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

npx squid-evm-typegen --abi src/abi/ERC721.json --output src/abi/erc721.ts

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 a number of environment variables.

Graphql server extensions

It is possible to extend squid-graphql-server(1) with custom type-graphql resolvers and to add request validation. More details will be added later.

Disclaimer

This is alpha-quality software. Expect some bugs and incompatible changes in coming weeks.