models.md

description
Checkpoint introduces a robust ORM to streamline your interactions with the database.

Models

Checkpoint enables data manipulation in your blockchain database without having to construct SQL queries directly. It features a capability to generate model objects from a GraphQL schema, and this guide will lead you through the process of creating and saving a model object into your database.

Generating Models

The first step is to generate the models from your GraphQL schema. This is done with the checkpoint generate command. Run it in your project environment like this:

yarn checkpoint generate

After running this command, your models will be created based on your GraphQL schema.

Importing Models

To use the generated models in your scripts, you need to import them. This is done with an import statement at the top of your file. For instance, if you've generated a Post model, you can import it like this:

import { Post } from '../.checkpoint/models';

This allows you to use the Post class to create new posts and save them to the database.

Defining Your Model

Each model is defined in a GraphQL schema file, such as schema.gql. Every model object will have a unique id along with other properties. Here's an example of a Post model:

scalar Text

type Post {
  id: String!
  author: String!
  content: Text!
  tag: String
  tx_hash: String!
  created_at: Int!
  created_at_block: Int!
}

Please note, this Post model is merely an example. Your actual model will have properties specific to your needs.

Creating a model Instance

To create a new instance of your model, you instantiate it with the id. Here's how you'd create a new Post:

const post = new Post(`${author}/${tx.transaction_hash}`);

You then set the other properties:

post.author = author;
post.content = content;
post.tag = tag;
post.tx_hash = tx.transaction_hash;
post.created_at = timestamp;
post.created_at_block = blockNumber;

Edit a model instance

Once the instance is defined, you can load an entity and edit it using loadEntity like that :

const post = await Post.loadEntity(id);
post.author = '0x123...';
await post.save();

Saving a model Instance

Once the instance is fully defined, you can save it into your database using the save method. This operation is asynchronous, so you should use await:

await post.save();