Version: v2

Migration Guide: HyperIndex v1 to v2

Introduction

Welcome to HyperIndex v2 - a major upgrade that significantly enhances your indexing experience! This new version introduces asynchronous processing, streamlined workflows, and improved flexibility for your indexers. With v2, you'll benefit from faster development, better performance, and a more intuitive API.

While the full release changes can be found in the v2.0.0 release notes, here are some key highlights before we dive into the comprehensive migration guide:

Handlers are now asynchronous, with loaders becoming an optional tool for additional optimizations.
Async-mode has been removed as it's no longer needed in v2.
Loaders (when used) are more expressive and directly connected to the handler context via their return type.
- In v2, you can access loader fields in the handler the same way you do in the loader, using an async 'get' function.
- The return type of the loader can be used to directly access loaded data in the handler via the context.
Indexing parameters with names that are reserved words in ReScript have been fixed.
Validation and autocompletion for config.yaml is now available. Enable it by adding # yaml-language-server: $schema=./node_modules/envio/evm.schema.json at the top of your config.yaml file.

These changes simplify the development process and provide a more consistent and powerful indexing experience. The following sections will guide you through the necessary steps to migrate your existing v1 indexers to v2.

Changes to Make

Handlers

Handlers are now asynchronous - add the async keyword and rename handlerAsync to handler.
You can use handlerWithLoader if you need a loader, otherwise, use handler directly.
The 'get' function is now asynchronous, so add an await before those functions.
No labeled entities.

Loaders

Loaders are merged into the handlers using handlerWithLoader.
Loading linked entities is done directly with promises in the loader.
Loaders are completely optional - only use the if you care about high throughput indexing.
Loaders return the required entities which are then used in the handler.
The dynamic contract registration moved from loaders to its own <ContractName>.<EventName>.contractRegister handler.
The return type of the loader is used directly in the handler to access the loaded data. No need to re-'get' it again in the handler.

Configuration

There is no async-mode anymore, so you can remove isAsync: true from each of the events in your config.yaml.
There is no more 'required_entities' in the config file. This includes sub-fields such as label and arrayLabels.

- isAsync: true

Removed entity labels and required entities.

- required_entities:
-   - name: User

Field Selection and Event Parameter Changes

In v2, the structure of the event parameter has changed significantly. Some fields have been moved or renamed, and new fields are available through the field_selection configuration.

Field selection allows you to add additional data points to each event that gets passed to your handlers. This feature enhances the flexibility and efficiency of your indexer, as by default you don't fetch data that isn't required.

To use field selection, add a field_selection section to your config.yaml file. For example:

field_selection:
  transaction_fields:
    - "from"
    - "to"
    - "hash"
    - "transactionIndex"
  block_fields:
    # Not required for migration, but more fields can be added here
    - "parentHash"

For an exhaustive list of fields that can be added and more detailed information about field selection, please refer to the Field Selection section in the Configuration File guide.

Note: By default, number, hash, and timestamp are already selected for block_fields and do not need to be configured.

'event' Parameter Changes

The structure of the event parameter has changed in v2. This affects loaders, handlers, and dynamic contract registration. Here are the key changes:

Block and transaction fields are now scoped under event.block and event.transaction respectively.
Some field names have changed:
- event.txOrigin is now event.transaction.from (requires adding to config)
- event.txTo is now event.transaction.to (requires adding to config)
- event.txHash is now event.transaction.hash (requires adding to config)
- event.blockTimestamp is now event.block.timestamp (no config change)
- event.blockNumber is now event.block.number (no config change)
- event.blockHash is now event.block.hash (no config change)

Miscellaneous breaking changes and deprecations

The context.Entity.load function is deprecated and should be replaced with direct calls to context.Entity.get in the loader.
The context.ParentEntity.loadField functions are deprecated and should be replaced with direct calls to context.ChildEntity.get.
Remove the Contract and Entity suffixes from the generated code.
For JavaScript/TypeScript users:
- The event param names are not uncapitalized anymore. So you might need to change event.params.capitalizedParamName to event.params.CapitalizedParamName.
For ReScript users:
- We moved to the built-in bigint type instead of the Ethers.BigInt.t.
- We migrated to ReScript 11 uncurried mode. Curried mode is not supported anymore. So you need to remove uncurried: false from your rescript.json file. Also, we vendored RescriptMocha bindings to support uncurried mode. Please use it instead of rescript-mocha.
The config parsing is more strict, unknown fields will result in an error.
- You can add # yaml-language-server: $schema=./node_modules/envio/evm.schema.json at the top of your 'config.yaml' file to get autocomplete and validation for the config file.

Migration Steps

1. Update Imports

Replace the old import statements with the new ones.

Before:

import {
  GreeterContract_NewGreeting_handler,
  // or you aren't using these `_` versions of the imports
  GreeterContract,
  // ...
} from "../generated/src/Handlers.gen"; // Not all imports still look like this, but on old indexers they do.

import {
  GreetingEntity,
  UserEntity,
  // ... other entities
} from "../generated/src/Types.gen";

After:

import {
  Greeter, // the Greeter Contract
  // ...
  Greeting, // the Greeting Entity
  User, // The User Entity
  // ... other entities
} from "generated"; // Note this requires adding the 'generated' folder to your 'optionalDependencies' in your package.json

2. Update Handler Definitions

Before:

/// or if your indexer is very old: GreeterContract_Event1_loader
GreeterContract.Event1.loader(({ event, context }) => {
  // Loader code
});
GreeterContract.Event1.handler(({ event, context }) => {
  // Handler code
});

After:

Greeter.Event1.handlerWithLoader({
  loader: async ({ event, context }) => {
    // Loader code
    return {
      /* loaded data, this data is available in the "handler" via the `loaderReturn` parameter */
    };
  },
  handler: async ({ event, context, loaderReturn }) => {
    // Handler code using loaderReturn
  },
});

Or without a loader:

Before:

GreeterContract.Event1.handler(({ event, context }) => {
  // Handler code
});

After:

Greeter.Event1.handler(async ({ event, context }) => {
  // Handler code
});

3. Dynamic Contract Registration

Use contractRegister for dynamic contract registration. Assuming there is an event called NewGreeterCreated that creates a contract called Greeter that has the address of the newGreeter as a field.

Before:

GreeterContract.NewGreeterCreated.loader(({ event, context }) => {
  context.contractRegistration.addGreeter(event.params.newGreeter);
});

After:

Greeter.NewGreeterCreated.contractRegister(({ event, context }) => {
  context.addGreeter(event.params.newGreeter);
});

4. Handling Entities

Before

const greetingInstance: GreetingEntity = {
  ...currentGreeting,
  // ...loaderReturn
};
context.Greeting.set(greetingInstance);

After

const greetingInstance: Greeting = {
  ...currentGreeting,
  // ...
};
context.Greeting.set(greetingInstance);

The only change is in the TypeScript/ReScript type for the entity 💪

5. Accessing Loaded Data

Access data via asynchronous get functions:

Before:

let currentEntity = context.Entity.get(event.srcAddress.toString());

After:

let currentEntity = await context.Entity.get(event.srcAddress.toString());

Access loaded data through the `loaderReturn` if you are using loaders:

Before:

let currentEntity = context.Entity.get(event.srcAddress.toString());

After:

const { currentEntity } = loaderReturn;

6. Loading Linked Entities

Before:

GreeterContract.Event1.loader(({ event, context }) => {
  context.Entity.load(event.srcAddress.toString(), {
    loadField1: true,
    loadField2: true,
  });
});

After:

Greeter.Event1.handlerWithLoader({
  loader: async ({ event, context }) => {
    const currentEntity = await context.Entity.get(event.srcAddress.toString());
    if (currentEntity == undefined) return null;

    const field1Instance = await context.Entity.getField1(
      currentEntity.field1_id
    );
    const field2Instance = await context.Entity.getField2(
      currentEntity.field2_id
    );

    return { currentEntity, field1Instance, field2Instance };
  },
});

7. Config File Changes

Before:

contracts:
  - name: Greeter
    sameRandomFieldThatIsntPartOfSchema: true
    handler: src/EventHandlers.ts
    events:
      - event: Greet(address indexed recipient, string greeting)
        isAsync: true
        requiredEntities:
          - name: User
            label: recipient
          - name: Greetings
            arrayLabels: previousGreetings

After:

contracts:
  - name: Greeter
    handler: src/EventHandlers.ts
    events:
      - event: Greet(address indexed recipient, string greeting)

8. Event Fields

Before (v1):

GreeterContract.Event1.handler(({ event, context }) => {
  console.log("The event timestamp and block number",
    event.txOrigin,
    event.txTo,
    event.transactionHash,
    event.transactionIndex,
    event.blockNumber,
    event.blockTimestamp,
    event.blockHash,
  )
});

After (v2):

Greeter.Event1.handlerWithLoader(async ({ event, context }) => {
  // NOTE: these fields are in the loader and the contractRegister function too
  console.log("The event timestamp and block number",
    event.transaction.from,
    event.transaction.to,
    event.transaction.hash,
    event.transaction.transactionIndex,
    event.block.number,
    event.block.timestamp,
    event.block.hash,
  );
});

And in your config.yaml file:

field_selection:
  transaction_fields:
    - "from"
    - "to"
    - "hash"
    - "transactionIndex"

Examples

As we upgrade public repos on GitHub, we'll add the commits of the upgrade to this page for reference:

Velodrome Indexer Upgrade Commit

Additional Tips

Make sure to thoroughly test your migrated code to catch any issues that might arise from the asynchronous nature of the new handlers.
If performance isn't a massive concern, you can simply use the handler function without a loader.

Migration Guide: HyperIndex v1 to v2

Introduction​

Changes to Make​

Handlers​

Loaders​

Configuration​

Field Selection and Event Parameter Changes​

'event' Parameter Changes​

Miscellaneous breaking changes and deprecations​

Migration Steps​

1. Update Imports​

2. Update Handler Definitions​

Or without a loader:​

3. Dynamic Contract Registration​

4. Handling Entities​

5. Accessing Loaded Data​

Access data via asynchronous get functions:​

Access loaded data through the loaderReturn if you are using loaders:​

6. Loading Linked Entities​

7. Config File Changes​

8. Event Fields​

Examples​

Additional Tips​

Introduction

Changes to Make

Handlers

Loaders

Configuration

Field Selection and Event Parameter Changes

'event' Parameter Changes

Miscellaneous breaking changes and deprecations

Migration Steps

1. Update Imports

2. Update Handler Definitions

Or without a loader:

3. Dynamic Contract Registration

4. Handling Entities

5. Accessing Loaded Data

Access data via asynchronous get functions:

Access loaded data through the `loaderReturn` if you are using loaders:

6. Loading Linked Entities

7. Config File Changes

8. Event Fields

Examples

Additional Tips