index.js

/**
 * Sets and saves a Sequelize instance and all
 * associated nested instances.
 * @param  {SequelizeInstance} instance
 * @param  {object} new_attrs
 * @return {null}
 *
 * A rundown of this function:
 * 1. Look up all the outgoing associations for the instance's model.
 * 2. Remove all existing associated instances from this instance.
 * 3. For each associated instance as described in new_attkrs, update it
 * 		if it already exists. Create it if it doesn't.
 * 4. Reassociate all old instances and associate new one.
 * 5. Save the instance.
 * 6. Return the updated populated object of this instance.
 */

const util = require('util');

function capitalizeFirst(string) {
  return string.charAt(0).toUpperCase() + string.slice(1);
}

module.exports = function deepUpdate(instance, new_attrs){

  console.log('go');
  // console.log('deep update: ', instance.dataValues, '-----> ', new_attrs);

  // Update literals
  // instance.set(new_attrs);

  // includeMap is a dictionary of attribute name to Sequelize instance
  const associations = instance.$options.includeMap;

  Object.keys(new_attrs).forEach((attr)=>{
    if((!associations) || (!associations[attr])){
      instance.set(attr, new_attrs[attr]);
    }
  });

  // Iterate through all of the associations from this model
  const update_associations = !associations ? [] : Object.keys(associations).map((associated)=>{

    if(new_attrs[associated] === undefined){
      return Promise.resolve();
    }

    const assoc = associations[associated];


    // Retrieve the associated model
    const assoc_model = associations[associated].model;

    const primary_key = Object.keys(assoc_model.primaryKeys)[0];

    // Determine whether this is a single association (containing one instance) or multi.
    const assoc_type  = instance.Model.associations[associated].associationType;
    const single = {
      HasMany: false,
      HasOne: true,
      BelongsTo: true,
      BelongsToMany: false
    }[assoc_type];


    // Get the name of the prototype function on @instance that will set the associated
    // instances for this association. Seqeulize capitalizes the name of the model.
    const set_fnc_name = (assoc.as && ('set' + capitalizeFirst(assoc.as))) || ('set' + capitalizeFirst(single ? assoc_model.options.name.singular : assoc_model.options.name.plural));
    const add_fnc_name = (assoc.as && (((single && 'set') || 'add') + capitalizeFirst(assoc.as))) || ((single ? 'set' : 'add') + capitalizeFirst(single ? assoc_model.options.name.singular : assoc_model.options.name.plural));

    // Remove all existing associated instances for the current key
    let prom = instance[set_fnc_name](null);


    // Get the NEW object for that association field, as defined by new_attrs
    let val = new_attrs[associated];

    // If the val is set to null or an empty array, stop acting on this association (i.e. do not re-associate any records)
    if(val === null || (Array.isArray(val) && val.length === 0)){
      return prom;
    }

    if(!Array.isArray(val)) val = [val];

    // For each object in this association key
    const update_instances = val.map((obj)=>{

      if(typeof obj === 'string' || typeof obj === 'number'){
        prom = prom.then(()=> assoc_model.findById(obj));
      }

      // If the object has an ID, retrieve it and update it.
      else if(obj[primary_key]){
        prom = prom.then(()=> assoc_model.findById(obj[primary_key], {include: [{all: true, nested: true}]})
          .then((result)=>{
            return deepUpdate(result, obj);
          }));
      }
      // If the object does not have an ID, it's new, so create it.
      else{
        prom = prom.then(()=> assoc_model.create(obj, {include: [{all: true}]}));
      }
      // Associate everything again.
      return prom
        .then((result)=>{

          // Determine which function on @instance prototype to use. "Add" fncs do not exist on single
          // assocations, only set.
          return instance[add_fnc_name](result);
        }).then((result)=>{
          return result;
        });
    });

    return Promise.all(update_instances);

  });

  return Promise.all(update_associations)
    .then(()=> instance.save())
    .then(()=> instance.reload())
    .then(()=>{
      // console.log('result', util.inspect(instance.dataValues, {depth: 2, colors: true}));
      return instance;
    })
    .catch((err)=> console.log(err));
};