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https://github.com/dappforce/subsocial-graphql

Sample project showcasing Hydra for Subsocial substrate chain
https://github.com/dappforce/subsocial-graphql

Last synced: 5 months ago
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Sample project showcasing Hydra for Subsocial substrate chain

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# 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.

## Prerequisites

* Node v14x
* Docker

## Bootstrap

```bash
# 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:

* `src/generated` - model/server definitions created by `codegen`. Do not alter the contents of this directory manually.
* `src/server-extension` - module with custom `type-graphql` based resolvers
* `src/types` - data type definitions for chain events and extrinsics created by `typegen`.
* `src/mappings` - mapping module.
* `lib` - compiled js files. The structure of this directory must reflect `src`.
* `.env` - hydra tools are heavily driven by environment variables defined here or supplied by a shell.

If you do not plan to extend GraphQl server you can delete `server-extension` module and then remove
`type-graphql` and `class-validator` dependencies.

## Development flow

If you modified `schema.graphql`:

```bash
# 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:

```bash
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:

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

# Delete old definitions
rm -rf src/types

# 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 check out https://docs.subsquid.io.