Rarity Rmrk

In order to start all subprocesses, run in different terminals:

npm run processor:start

npm run start-ipfs

npm run query-node:start

npm run fetch-and-save-nfts

Sample Hydra Project

This is a sample project generated by hydra-cli scaffold. Experiment by modifying schema.graphql and the mappings in the mappings folder.

NOTE

Do not manually npm update, and only execute npm ci instead of npm i. Newer versions of some packages cause npm run query-node:start to not work.

Prerequisites

• Node v14x
• Docker

Bootstrap

# The dependencies setup relies on de-duplication, use `ci` to get everything right
npm ci

# Start a postgres instance
docker-compose up db # add optional -d flag to detach from terminal

# Apply migrations related to the processor's state keeping tables
npm run processor:migrate

# Apply the project's migrations
npm run db:migrate

# Now you can start processing chain data
npm run processor:start

# The above command will block
# Open a separate terminal and launch the graphql server to query the processed data
npm run query-node:start

Project structure

Hydra tools expect a certain directory layout:

• generated - model/server definitions created by codegen. Do not alter the contents of this directory manually.
• server-extension - a place for custom data models and resolvers defined via *.model.ts and *.resolver.ts files.
• chain - data type definitions for chain events and extrinsics created by typegen.
• mappings - mapping module.
• .env - hydra tools are heavily driven by environment variables defined here or supplied by a shell.

Development flow

If you modified schema.graphql:

# Run codegen to re-generate model/server files
npm run codegen

# Analyze database state and create a new migration to match generated models
npm run db:create-migration # add -n "myName" to skip the migration name prompt

# Apply the migrations
npm run db:migrate

You might want update the Initial migration instead of creating a new one (e.g. during the development phase when the production database is not yet set up). In that case it convenient to reset the database schema and start afresh:

rm db/migrations/LastUnappliedMigration.ts
npm run db:reset
npm run db:create-migration
npm run db:migrate

To generate new type definitions for chain events and extrinsics:

# Review typegen section of manifest.yml (https://docs.subsquid.io/hydra-typegen)

# Delete old definitions
rm -rf chain

# Run typegen tool
npm run typegen

Self-hosted indexer

It is recommended to use a readily set up indexer if available. It takes some time for a freshly started indexer to get in sync with chain and catch the events.

Have a look at ./indexer/docker-compose.yml for an example of how you can set up a self-hosted version.

Misc

For more details, please checkout https://docs.subsquid.io.