active-graph-record

ActiveRecord implementation for ES2015 with neo4j as back-end

this software is beta stage and is not intended to be used in serous production projects developers of this software are not responsible for data loss and corruption, lunar eclipses and dead kittens

What is it?

ActiveRecord is common pattern in software development which declares that there is special class or classes who are responsible for database reflection, line-by-line or node-by-node.

Neo4j is Graph Database, it's schema-less and ACID-compliant.

How to use it?

Dead simple. It's mostly purposed for ES2015-featured JavaScript, so all of the examples are written using it.

const {Connection, Record} = require('active-graph-record')
 
class Entry extends Record {}
Entry.connection = new Connection('http://neo4j:password@localhost:7474');
 
// or with babel-preset-stage-1
// here and further where static properties are used they can be replaced
// by assignment of property to class function, like shown above
 
class Entry extends Record {
    static connection = new Connection('http://neo4j:password@localhost:7474');
}
 
Entry.register() //creates indexes and makes some internal magic for resolving
 
async function main() {
    const entry = new Entry()
    entry.foo = 'bar'
    await entry.save()
 
    const entries = await Entry.where({foo: 'bar'})
    console.log(entries.length) // => 1
    console.log(entries[0].foo) // => 'bar'
}

Wait, but I need relations

no problems. It's dead simple too:

const {Connection, Record, Relation} = require('active-graph-record')
class ConnectedRecord extends Record {
    static connection = new Connection('http://neo4j:password@localhost:7474');
}
 
class RecordObject extends ConnectedRecord {
    subjects = new Relation(this, 'relation' /*internal relation label-name*/);
 
    //note: it is NOT a static property. It can be replaced with
    constructor(...args){
        super(...args);
        this.subjects = new Relation(this, 'relation' /*internal relation label-name*/);
    }
}
 
class RecordSubject extends ConnectedRecord {
    //target is optional! and direction is optional too, it should be -1 for reverse relations.
    subjects = new Relation(this, 'relation', {target: Object, direction: -1});
}
 
RecordObject.register()
RecordSubject.register()
 
async function main() {
    const object = await new RecordObject({baz: true}).save()
    const subject = await new RecordSubject().save()
    await object.subjects.add(subject)
 
    console.log(await subject.objects.size()) // => 1
    const objects = await subject.objects.entries()
    console.log(objects[0].baz) => //true
}

even for deep relations:

class User extends ConnectedRecord {
    roles = new Relation(this, 'has_role', {target: Role});
    permissions = new Relation(this.roles, 'has_permission', {target: Permission});
 
    async hasPermission(permission) {
        return await this.permissions.has(permission)
    }
}
 
class Role extends ConnectedRecord {
    users = new Relation(this, 'has_role', {target: Role, direction: -1});
    permissions = new Relation(this, 'has_permission', {target: Permission});
}
 
class Permission extends ConnectedRecord {
    roles = new Relation(this, 'has_permission', {target: Role, direction: -1});
    users = new Relation(this.roles, 'has_role', {target: User, direction: -1});
}

Relation instances have bunch of pretty methods to use (you can always pass a transaction as last argument):

class Record {
    async only(): Record
    async only(null | Record): void
 
    async has(records: Array<Record>): bool
    async intersect(records: Array<Record>): Array<Record>
    async add(records: Array<Record>): void
    async delete(records: Array<Record>): void
 
    async clear(): void
    async size(): number
    async entries(): Array<Record>
 
    async where(params?: WhereParams, opts?: WhereOpts): Array<Record>
}

AGR-backed fields

AGR automatically brings uuid key (cannot be re-defined), created_at and updated_at (in milliseconds) fields when record is reflected.

OK, but how can I make complex queries?

Record and Relation have static where method to use for querying. All details are provided in API page, in brief - order, limit, offset can be used for filtering, equality, existence, numeric (greater/less), string (starts/ends with, contains), array (contains/includes) queries are available

Examples:

Entry.where({foo: 1000}, {limit: 10, offset: 10, order: 'created_at'})
Entry.where({updated_at: {$gte: Date.now() - 1000}}, {order: ['created_at DESC']})
Entry.where({foo: {$exists: true, $startsWith: ['b', 'ba', 'baz'], $endsWith: 'bar', $contains: 'z'}})
 
// here e.g. {foo: [1,2,3,4,5], bar: 3} will be reflected.
// $has stands for "db record has fields", $in - for "db record is in list of possible fields"
Entry.where({foo: {$has: [1,2,3]}, bar: {$in: [1,2,3]}})
 
//$in can also work with array
Entry.where({foo: {$in: [[0], [1,2,3,4,5]]}}})

Hooks?

Sure. beforeCreate, afterCreate, beforeUpdate, afterUpdate, beforeDestroy, afterDestroy are available hooks

class Entry extends Record {
    async beforeCreate() {
        //this.connection points here to transaction, so you have to pass it if calling other classes
        const test = await Test.where({id: this.id}, this.connection)
        this.testId = test.testId
    }
}

Transactions and atomicity?

Yes, AGR has transactions. Hooks (see above) are always inside a transaction. They can be used by using special decorator (with babel-plugin-transform-decorators-legacy, will be changed to new syntax when new spec will become stable) @acceptsTransaction({force: true}) or called explicitly by connection.transaction() All transactions should be committed or rolled back. On SIGINT AGR will attempt to rollback all not closed yet transactions. By default Neo4j rolls back transactions in 60 seconds after last query.

Good example of transaction usage is Record#firstOrCreate sugar-ish method:

class Record {
    @acceptsTransaction
    static async firstOrInitialize(params) {
        const tx = this.connection.transaction()
        let [result] = await this.where(params, {limit: 1}, tx.transaction())
        if (!result)
            result = await new this().save(params, tx.transaction())
        await tx.commit()
        return result
    }
}

Roadmap

• sort
• offset and limit
• has
• deep relations
• indexes
• rich Record.where query syntax ($lt, $gt, $lte, $gte, $has, $in and so on)
• one-to-one relations
• relations validation
• total test coverage
• performance optimisations
• optimistic and pessimistic locks?
• tests for transaction usage
• tests for eventEmitter