Example Watcher

Setup

First try the stack orchestrator to quickly get started. Advanced users can see here for instructions on setting up a local environment by hand.

Run the following command to install required packages:

yarn

Run

In packages/graph-node, deploy an Example contract:
```
yarn example:deploy
```
Set the returned address to the variable $EXAMPLE_ADDRESS:
```
EXAMPLE_ADDRESS=<EXAMPLE_ADDRESS>
```
In packages/graph-node/test/subgraph/example1/subgraph.yaml:
- Set the source address for Example1 datasource to the EXAMPLE_ADDRESS.
- Set the startBlock less than or equal to the latest mined block.
Build the example subgraph:
```
yarn build:example
```
Run the job-runner:
```
yarn job-runner
```
Run the watcher:
```
yarn server
```
The output from the block handler in the mapping code should be visible in the job-runner for each block.

Run the following GQL subscription at the graphql endpoint http://127.0.0.1:3008/graphql

subscription {
  onEvent {
    event {
      __typename
      ... on TestEvent {
        param1
        param2
      },
    },
    block {
      number
      hash
    }
  }
}

In packages/graph-node, trigger the Test event by calling a example contract method:
```
yarn example:test --address $EXAMPLE_ADDRESS
```
- A Test event shall be visible in the subscription at endpoint.
- The subgraph entity Category should be updated in the database.
- An auto-generated diff-staged entry State should be added.

Run the query for entity in at the endpoint:

query {
  category(
    block: { hash: "EVENT_BLOCK_HASH" },
    id: "1"
  ) {
    __typename
    id
    count
    name
  }
}

Run the getState query at the endpoint to get the latest State for EXAMPLE_ADDRESS:

query {
  getState (
    blockHash: "EVENT_BLOCK_HASH"
    contractAddress: "EXAMPLE_ADDRESS"
    # kind: "checkpoint"
    # kind: "diff"
    kind: "diff_staged"
  ) {
    cid
    block {
      cid
      hash
      number
      timestamp
      parentHash
    }
    contractAddress
    data
  }
}

diff states get created corresponding to the diff_staged states when their respective blocks reach the pruned region.
In packages/graph-test-watcher:
- After the diff state has been created, create a checkpoint:
```
yarn checkpoint create --address $EXAMPLE_ADDRESS
```
  - A checkpoint state should be created at the latest canonical block hash.
  - Run the getState query again at the endpoint with the output blockHash and kind checkpoint.
All the State entries can be seen in pg-admin in table state.

Customize

Indexing on an event:
- Edit the custom hook function handleEvent (triggered on an event) in hooks.ts to perform corresponding indexing using the Indexer object.
- While using the indexer storage methods for indexing, pass diff as true if default state is desired to be generated using the state variables being indexed.
Generating state:
- Edit the custom hook function createInitialState (triggered if the watcher passes the start block, checkpoint: true) in hooks.ts to save an initial State using the Indexer object.
- Edit the custom hook function createStateDiff (triggered on a block) in hooks.ts to save the state in a diff State using the Indexer object. The default state (if exists) is updated.
- Edit the custom hook function createStateCheckpoint (triggered just before default and CLI checkpoint) in hooks.ts to save the state in a checkpoint State using the Indexer object.
The existing example hooks in hooks.ts are for an ERC20 contract.

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Example Watcher

Setup

Run

Customize

4.1 KiB

Raw Blame History