[](https://gitpod.io/#https://github.com/subsquid/squid-evm-template) # Minimal EVM squid This is a starter template of a squid indexer for EVM networks (Ethereum, Polygon, BSC, etc.). See [Squid SDK docs](https://docs.subsquid.io/) for a complete reference. To extract EVM logs and transactions by a topic or a contract address, use `EvmBatchProcessor.addLog()` and `EvmBatchProcessor.addTransaction()` methods of the `EvmBatchProcessor` instance defined in `src/processor.ts`. The requested data is transformed in batches by a single handler provided to the `processor.run()` method. For a full list of supported networks and config options, check the [`EvmBatchProcessor` overview](https://docs.subsquid.io/develop-a-squid/evm-processor/) and the [configuration page](https://docs.subsquid.io/develop-a-squid/evm-processor/configuration/). For a step-by-step migration guide from TheGraph, see [the dedicated docs page](https://docs.subsquid.io/migrate/migrate-subgraph/). Dependencies: Node.js, Docker. ## Quickstart ```bash # 0. Install @subsquid/cli a.k.a. the sqd command globally npm i -g @subsquid/cli # 1. Retrieve the template sqd init my_squid_name -t evm cd my_squid_name # 2. Install dependencies npm ci # 3. Start a Postgres database container and detach sqd up # 4. Build and start the processor sqd process # 5. The command above will block the terminal # being busy with fetching the chain data, # transforming and storing it in the target database. # # To start the graphql server open the separate terminal # and run sqd serve ``` A GraphiQL playground will be available at [localhost:4350/graphql](http://localhost:4350/graphql). ## Dev flow ### 1. Define database schema Start development by defining the schema of the target database via `schema.graphql`. Schema definition consists of regular graphql type declarations annotated with custom directives. Full description of `schema.graphql` dialect is available [here](https://docs.subsquid.io/basics/schema-file). ### 2. Generate TypeORM classes Mapping developers use TypeORM [EntityManager](https://typeorm.io/#/working-with-entity-manager) to interact with target database during data processing. All necessary entity classes are generated by the squid framework from `schema.graphql`. This is done by running `sqd codegen` command. ### 3. Generate database migrations All database changes are applied through migration files located at `db/migrations`. `squid-typeorm-migration(1)` tool provides several commands to drive the process. ```bash ## drop create the database sqd down sqd up ## replace any old schemas with a new one made from the entities sqd migration:generate ``` See [docs on database migrations](https://docs.subsquid.io/basics/db-migrations) for more details. ### 4. Import ABI contract and generate interfaces to decode events It is necessary to import the respective ABI definition to decode EVM logs. One way to generate a type-safe facade class to decode EVM logs is by placing the relevant JSON ABIs to `./abi`, then using `squid-evm-typegen(1)` via an `sqd` script: ```bash sqd typegen ``` See more details on the [`squid-evm-typegen` doc page](https://docs.subsquid.io/evm-indexing/squid-evm-typegen). ## Project conventions Squid tools assume a certain [project layout](https://docs.subsquid.io/basics/squid-structure): * All compiled js files must reside in `lib` and all TypeScript sources in `src`. The layout of `lib` must reflect `src`. * All TypeORM classes must be exported by `src/model/index.ts` (`lib/model` module). * Database schema must be defined in `schema.graphql`. * Database migrations must reside in `db/migrations` and must be plain js files. * `sqd(1)` and `squid-*(1)` executables consult `.env` file for environment variables. # ERC721_Token_Indexer-