tabel/src/relations/Relation.js

A simple orm for PostgreSQL which works with simple javascript objects and arrays

/**
 * Already used methods:
 * - setName
 * - forModel
 * - constrain
 * - eagerLoad
 * - load
 */

const {isString} = require('lodash');

const Scope = require('../Scope');
const Track = require('../Track');

class Relation {
  constructor(ownerTable) {
    this.ownerTable = ownerTable;
    this.constraints = new Track();
    this.activeModel = null;
    this.relationName = null;
  }

  setName(relationName) {
    this.relationName = relationName;
    return this;
  }

  forModel(model) {
    this.activeModel = model;
    return this;
  }

  constrain(constraint, label='constraint') {
    this.constraints.push(new Scope(constraint, label));
    return this;
  }

  eagerLoad(...args) {
    return this.constrain((t) => t.eagerLoad(...args), 'eagerLoad');
  }

  load(fromModels=[]) {
    if (fromModels.length === 0) {
      return Promise.resolve(fromModels);
    }

    return this.getRelated(fromModels).then((relatedModels) => {
      return this.matchModels(this.initRelation(fromModels), relatedModels);
    });
  }

  initRelation(fromModels=[]) {
    throw new Error('not implemented');
  }

  getRelated(fromModels=[]) {
    throw new Error('not implemented');
  }

  matchModels(fromModels=[], relatedModels=[]) {
    throw new Error('not implemented');
  }

  jointLabel(label, {isLeftJoin=false}) {
    return `${
      isLeftJoin ? 'leftJoin' : 'join'
    }.${this.constructor.name}.${this.relationName}${
      isString(label) ? `.${label}` : ''
    }`;
  }

  pivotJointLabel(label, {isLeftJoin=false}) {
    return `${this.jointLabel(label, {isLeftJoin})}.pivot${
      isString(label) ? `.${label}` : ''
    }`;
  }

  throughJointLabel(label, {isLeftJoin=false}) {
    return `${this.jointLabel(label, {isLeftJoin})}.through${
      isString(label) ? `.${label}` : ''
    }`;
  }

  join() {
    throw new Error('not implemented');
  }

  joinPivot() {
    throw new Error('not imeplemented');
  }

  joinThrough() {
    throw new Error('not imeplemented');
  }
}

module.exports = Relation;