Setting up Database Schema

The studio.schema.ts file is a TypeScript file that defines the databases and schema for the data stored within them. It outlines the entities and their relationships in the indexed blockchain data.

Each project contains a single studio.schema.ts file where all schema definitions are centralised.

const Transfer = {
  name: "Transfer",
  description: "This database stores ERC20 transfer events",
  db: "mongodb",
  type: "managed",
  reorg: true,
  properties: {
    from: "string?",
    to: "string?",
    amount: "string?",
  },
};

module.exports = { Transfer };

No comments are allowed in this file.

Key Sections:

• name: The name of the database being defined.

• description: The description about database.

• db: Specifies the database type, either mongodb or postgres.

• type: Defines whether the database is managed by Blockflow or if you're using a private database.

• reorg: Indicates whether the database should be reorganisation (reorg) aware.

• properties: Contains the schema definition, including field names and their types, for the data stored in the database.

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Creating Indexed Fields

In addition to specifying the data types for your schema fields, you can also define whether a field should be indexed to improve query performance. Indexing is particularly useful for fields that are frequently used in filtering or sorting operations.

To mark a field as indexed, simply add @ at the end of the field’s type, as shown below:

const Transfer = {
  name: "Transfer",
  description: "This database stores ERC20 transfer events",
  db: "mongodb",
  type: "managed",
  reorg: true,
  properties: {
    from: "string@", // This field is indexed
    to: "string?",
    amount: "string?",
  },
};

module.exports = { Transfer };

---

Generated Types

Once you've finished defining all your databases, run the blockflow typegen command. This will generate two important files in the src/types folder: schema.ts and graphql.ts.

• schema.ts: Contains the schemas and TypeScript interfaces for the databases you defined in your project.

export const Transfer = {
  "name": "XXXX-XXXX-XXXX-XXXX-Transfer",
  "db": "mongodb",
  "type": "managed",
  "properties": {
    "from": "string?",
    "to": "string?",
    "amount": "string?"
  },
  "reorg": true
};

export interface ITransfer {
  from: string;
  to: string;
  amount: string;
}

• graphql.ts: Contains auto-generated GraphQL entities that are used in custom GraphQL queries and mutations.

import { Entity, PrimaryColumn, Column, BaseEntity } from "typeorm";
import { ObjectType, Field, ID } from "type-graphql";
import "reflect-metadata";

@Entity()
@ObjectType()
export class GTransfer extends BaseEntity {

  @Column()
  @Field({ nullable: true })
  from?: string;

  @Column()
  @Field({ nullable: true })
  to?: string;

  @Column()
  @Field({ nullable: true })
  amount?: string;

  @Column()
  @Field(() => Number)
  _blocknumber!: number;

  @Column()
  @Field()
  _blockhash!: string;

  @Column()
  @Field()
  _chainId!: string;

  @Column()
  @Field(() => Number)
  _version!: number;

  @Column()
  @Field()
  _refId!: string;
}

These files are essential for further development, providing type safety and facilitating interactions with your database and GraphQL API.