neogen

What is neogen?

neogen is a code generation tool for neogma, focused on automating and streamlining the development of Neo4j object-graph mappings (OGMs). It facilitates efficient model generation, relationship setup, and method creation, while ensuring type safety in Neo4j-based projects.

What problems does it solve ?

• Relations validation:
• Efficiency - neogma introduces great type safety, hints but with it requires more editing: if one property changes - you would need to edit two declaration, neogen tries to solve this issue
• Structure

Motivation

Developed with inspiration from Ruby on Rails' rails g, neogen eliminates the repetitive and error-prone aspects of manual Neo4j OGM setup in neogma. Its primary goal is to enhance development efficiency and accuracy in managing Neo4j database schemas and relationships.

How to use

Installing

yarn add neogen

Create config file

touch neogen.config.ts

Update your connection

At this point assuming your project' structure to be like this

├── neogen.config.ts
├── package.json
└── src
    ├── index.ts
    ├── neo4j.ts
    └── models

Where neo4j.ts contains instance of Neogma connection:

It's required to add this lines so that neogen could find connection, since models depend on it's value

import { neogen } from "neogen";
// ...
const neogma = new Neogma(...
// ...
neogen.setInstance(neogma)

Write desired schema:

Update neogen.config.ts file:

import { neogen } from "neogen";

neogen.generateAll({ // settings
    generateBase: true,
    outputFolder: './src/models'
}, [{ // models
    label: 'Post',
    schema: {
        uuid: 'string',
        text: 'string'
    },
    primaryKeyField: 'uuid'
}, {
    label: 'User',
    schema: {
        name: 'string',
        uuid: 'string',
        online: 'boolean'
    },
    primaryKeyField: 'uuid'
}], { // relations
    POST_POSTED_BY: {
        User: 'posted',
        Post: 'of_user',
    },
    POST_LIKED_BY: {
        User: 'likes',
        Post: 'liked_by'
    },
})

Adjust your package.json

"scripts": {
    "neogen": "ts-node neogen.config.ts",

And finally run

yarn run neogen

Result

With this configuration it'll generate 6 files

├── neogen.config.ts
├── package.json
└── src
    └── models
        ├── __base.ts
        ├── __relations.ts
        ├── post.ts
        ├── post_.ts
        ├── user.ts
        └── user_.ts

• post, user - the ones containing all type and meta information
• post_ and user_ - contains static and instance methods of the models
• __relations - contains all relations defenitions, it's important to import it in main file
• __base - contains base of instance and statics methods if generateBase option is enabled

Update your main file

It's important to import it in this order in your main/index file before using any models:

import './neo4j' // or whatever your file with neo4j connection is named
import './models/__relations'

relations DSL explanation

Give this relationship declrartion:

const rel = {
  POST_POSTED_BY: {
        User: 'posted',
        Post: 'of_user',
    }
}

It would translate to

(:User)-[:POST_POSTED_BY]->(:Post)

Or if you want node relation to itself you can make

const rel = {
  POST_POSTED_BY: {
    Comment: ['replied_to', 'replies']
  }
}

Which would result to

(:Comment)-[:POST_POSTED_BY]->(:Comment)

Or you can use raw relation notation:

neogen.generateAll({
    rawRelation: [
        {
            from: 'Session',
            to: 'Channel',
            direction: 'in',
            label: 'TEST',
            alias: 'test'
        }
        ...

TODO

• Core
  • [ ] Validate relations
  • [x] Auto instance import
  • [ ] Relation getters
• Organizational
  • [ ] Eslint
  • [x] Use Github workflow for publishing npm
  • [x] Add tests