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Smart Contract Indexer (ERC20, ERC721, ERC1155)

Smart contract indexing program & api.

Intro

A smart contract indexer that indexes transfer events and exposes an API to query them. The indexed data is stored into a db. Tables are generated as needed per contract & chain id for each type of table that is needed.

The purpose is to make it easier, faster and mainly cheaper to query event data.

Support

Our aim is to support the most popular token standards.

• ERC20
• ERC721
• ERC1155

Installation

go get ./...

Setup .env file

cp .example.env .env

Replace URLs with your own RPC urls

Build (optional)

This will build for the current platform you are on. It's possible to cross-compile if you provide flags.

go build -o indexer ./cmd/node/main.go

Linux cross-compilation

GOARCH=amd64 GOOS=linux go build -o indexer ./cmd/node/main.go

Make it executable

chmod +x indexer

Run indexer

Run the build (doesn't require Go to be installed)

./indexer

Run from the source files directly (Go needs to be installed)

go run cmd/indexer/main.go

Standard with an http url:

go run cmd/indexer/main.go -env .env

If you have a websocket url:

go run cmd/indexer/main.go -env .env -ws

You can also omit the env flag if you set them manually yourself before running the program (containerization setup where you don't want to include the .env in the image).

go run cmd/indexer/main.go

Flags

-env [string]: path to your .env file. (default = '')

-port [int]: port you would like the REST API to be exposed on. (default = 3000)

-sync [int]: the amount of seconds to wait before syncing events from latest blocks. (default = 5)

-ws [bool]: include this flag if you would like to use the websocket url instead. (default = false)

-rate [int]: control how many blocks get processed at a time. (default = 99)

Sync

When the indexer starts up, logs are downloaded block by block to make sure all events are up to date.

After the initial indexing work is done, indexer will sync the latest blocks every few seconds.

Websocket Sync

When the indexer starts up, it will simply listen for each event on the contracts you want.

Logs that are emitted are processed and inserted into the DB.

Standards

Syncing is done by standards, querying is done by event types on contracts. ERC20, ERC721, ERC1155 are supported as of this moment. We have only implemented indexing of transfer events.

Endpoints

Logs

Fetch all logs before a given maxDate with a limit and offset.

[GET] /logs/v2/transfers/{contract_address}/{address}?maxDate=2023-06-14T21%3A46%3A25%2B02%3A00&limit=10&offset=0

URL params

{contract_address}: the address of the token contract you would like to query.

{address}: the address of the "to" or "from" from an event log.

Query params

maxDate: a url encoded date string in iso format (RFC3339). Default = now.

limit: for pagination, the maximum amount of items that should be returned. Default = 20.

offset: for pagination, the row at which the query should start from. Default = 0.

New Logs

Fetch all new logs after a give fromDate with a limit

[GET] /logs/v2/transfers/{contract_address}/{address}/new?fromDate=2023-06-14T21%3A46%3A25%2B02%3A00&limit=10

URL params

{contract_address}: the address of the token contract you would like to query.

{address}: the address of the "to" or "from" from an event log.

Query params

fromDate: a url encoded date string in iso format (RFC3339). Default = now.

limit: for pagination, the maximum amount of items that should be returned. Default = 10.

Protected routes

To ensure the right people make the right requests, we use signed requests.

Headers

X-Signature: a base64 encoding of the entire request body.

X-Address: the hex address of the key that was used to generate the signature.

Body

{
    "data": data, // base64 encoded data
    "encoding": "base64", // how is the data encoded
    "expiry": expiry,
    "version": 2
}

Events [Protected]

[POST] /events

Adding a new event will trigger indexing of event logs starting from the current latest block on the network until last_block. Once indexing is done, last_block will be updated so that we only partially re-index next time.

Body

{
    "contract": "0xDe365ad2E3edA7739f9d61aF96288357CEf38c0a",
    "start_block": 43640241,
    "last_block": 43640241,
    "standard": "ERC20",
    "name": "Brussels Bar Token",
    "symbol": "BBT"
}

Pin a profile with image [Protected]

Create or update a profile.

[PUT] /profiles/{address}

URL params

{address}: the address that this profile belongs to.

Headers

X-Signature & X-Address

Multi-part form file

A jpg, png or gif.

Multi-part form body

{
    "data": data, // base64 encoded data
    "encoding": "base64", // how is the data encoded
    "expiry": expiry,
    "version": 2
}

Data

indexer.Profile

Update a pinned profile [Protected]

Updates a profile with no image modifications.

[PATCH] /profiles/{address}

URL params

{address}: the address that this profile belongs to.

Headers

X-Signature & X-Address

Body

{
    "data": data, // base64 encoded data
    "encoding": "base64", // how is the data encoded
    "expiry": expiry,
    "version": 2
}

Data

indexer.Profile

Un-pin a pinned profile [Protected]

Un-pins a profile.

[DELETE] /profiles/{address}

URL params

{address}: the address that this profile belongs to.

Headers

X-Signature & X-Address

Add a push token [Protected]

Create or update a push token for a give token contract.

[PUT] /push/{contract_address}

URL params

{contract_address}: the address of the token contract this is for.

Headers

X-Signature & X-Address

Body

{
    "data": data, // base64 encoded data
    "encoding": "base64", // how is the data encoded
    "expiry": expiry,
    "version": 2
}

Data

indexer.PushToken

Delete a push token [Protected]

Delete a push token for a give token contract and account.

[DELETE] /push/{contract_address}/{address}/{token}

URL params

{contract_address}: the address of the token contract this is for.

{address}: the address that this token belongs to.

{token}: the token to delete.

Headers

X-Signature & X-Address

Body

{
    "data": data, // base64 encoded data
    "encoding": "base64", // how is the data encoded
    "expiry": expiry,
    "version": 2
}

Data

indexer.PushToken

Storage

We use postgres. If you have docker installed, you can spin up an instance using docker compose up db.

The tables will be generated as needed.

Push Notifications

We use Firebase Messaging to send push notifications. The reasoning behind this is that we are obliged to for Android and that they support iOS. This makes it very easy to use a common interface for both.

A firebase.json service account is required for this functionality.