index.js

'use strict';

const _ = require('./vendor/lodash');
const Sequelize = require('sequelize');

const PLAIN_TYPES = ['string', 'number', 'boolean'];
const ARRAY_TYPES = [
  'Array',
  'Int8Array',
  'Uint8Array',
  'Uint8ClampedArray',
  'Int16Array',
  'Uint16Array',
  'Int32Array',
  'Uint32Array',
  'Float32Array',
  'Float64Array'
];
const DOC_DB_TYPES = ['JSON', 'JSONB', 'HSTORE'];

function _padWith0(v) {
  v = '' + v;
  return v.length == 1 ? '0' + v : v;
}

function encodeToJSON(value, options) {
  let className = (value && typeof(value.constructor) === 'function') ? value.constructor.name : null;

  if(PLAIN_TYPES.indexOf(typeof(value)) > -1 || value === null) {

    return value;

  } else if(ARRAY_TYPES.indexOf(className) > -1) {

    let result = [];
    for(let e of value) {
      result.push(encodeToJSON(e, options));
    }
    
    return result;

  } else if(value instanceof Date) {

    return value.toISOString();

  } else if(value instanceof Buffer) {
    
    return value.toString(options.blobEncoding);
  
  } else if(typeof(value) === 'object') {

    let result = {};
    for(let key in value) {
      if(value.hasOwnProperty(key)) {
        result[key] = encodeToJSON(value[key], options);
      }
    }

    return result;

  } else {
    throw new Error('Can\'t encode ' + typeof(value) + ' to JSON');
  }
}

const _policies = { FAIL: 1, SKIP: 2, SET_NULL: 3 };

let _defaultOptions = {
  encoder: encodeToJSON,
  undefinedPolicy: _policies.SKIP,
  copyJSONFields: true,
  simpleDates: true,
  encoderOptions: {
    blobEncoding: 'base64'
  }
};

function _getSchemeFromModel(model, scheme) {
  if(model.serializer && model.serializer.schemes) {
    return model.serializer.schemes[scheme] || null;
  }

  return null;
}

function _isModel(obj, sequelize, seqVer) {
  if(seqVer >= 5) {
    return obj.prototype instanceof Sequelize.Model;
  } else if (seqVer >= 4) {
    return obj.prototype instanceof sequelize.Model;
  } else {
    return obj instanceof sequelize.Model;
  }
}

function _isModelInstance(obj, sequelize, seqVer) {
  if(seqVer >= 5) {
    return obj instanceof Sequelize.Model;
  } else if (seqVer >= 4) {
    return obj instanceof sequelize.Model;
  } else {
    return obj instanceof sequelize.Instance;
  }
}

function _getModelFromInstance(inst, seqVer) {
  if(seqVer >= 4) {
    return inst.constructor;
  } else {
    return inst.Model;
  }
}

function _isSpecificModelInstance(obj, model, seqVer) {
  if(seqVer >= 4) {
    return obj instanceof model;
  } else {
    return obj instanceof model.Instance;
  }
}

class Serializer {
  constructor(model, scheme, options) {
    const sequelize = model.sequelize || {};
    let seqVer = 1 * (sequelize.constructor.version || '-').split('.', 2)[0]; // major version as number
    let schemeName = null;
    
    if(!(sequelize.Model || Sequelize.Model) || isNaN(seqVer) || !_isModel(model, sequelize, seqVer)) {
      throw new Error('' + model + ' is not a valid Sequelize model');
    }

    if(typeof(scheme) === 'string') {
      schemeName = scheme;
      scheme = _getSchemeFromModel(model, scheme);
    } else if(!scheme) {
      if(model.serializer) {
        let schemes = model.serializer.schemes || {};
        
        if(model.serializer.defaultScheme) {
          schemeName = model.serializer.defaultScheme;
          scheme = schemes[model.serializer.defaultScheme];
        } else {
          if(schemes.default) {
            schemeName = 'default';
            scheme = schemes.default;
          } else {
            scheme = {};
          }
        }
      } else {
        scheme = {};
      }
    }

    if(!scheme || typeof(scheme) !== 'object') {
      throw new Error('Invalid serialization scheme for ' + model.name + ': ' + scheme);
    }

    this._origOptions = options;
    this._options = _.defaultsDeep(
      {}, 
      options, 
      scheme.options, 
      model.serializer ? model.serializer.options : null, 
      _defaultOptions
    );
    
    this._seq = sequelize;
    this._seqVer = seqVer;
    this._model = model;
    this._scheme = scheme;
    this._schemeName = schemeName;

    this._attr = {
      all: [],
      virtual: [],
      pk: [],
      fk: [],
      assoc: [],
      blob: [],
      doc: [],
      auto: []
    };

    this._collectAttrs();
    this._attrList = this._compileAttributesList(scheme);
  }

  _collectAttrs() {
    let attr = this._attr;
    let a, typeName;

    const rawAttributes = this._model.attributes || this._model.rawAttributes;

    for(let name in rawAttributes) {
      if(!rawAttributes.hasOwnProperty(name)) continue;

      a = rawAttributes[name];
      
      if(this._options.attrFilter && this._options.attrFilter(a, this._model) === false) {
        continue;
      }
      
      typeName = a.type.key;
      
      attr.all.push(a.fieldName);
      
      if(a.primaryKey) attr.pk.push(a.fieldName);
      if(a.references) attr.fk.push(a.fieldName);
      if(a._autoGenerated) attr.auto.push(a.fieldName);
      
      if(typeName == 'VIRTUAL') attr.virtual.push(a.fieldName);
      else if(typeName == 'BLOB') attr.blob.push(a.fieldName);
      else if(DOC_DB_TYPES.indexOf(typeName) > -1) attr.doc.push(a.fieldName);
    }

    for(let name in this._model.associations) {
      //if(!this._model.attributes.hasOwnProperty(name)) continue;
      a = this._model.associations[name];
      attr.assoc.push(a.as);
    }
  }

  _expandAttributes(list) {
    let attr = this._attr;
    let result = [];

    for(let a of list) {
      if(a[0] == '@') {
        result = result.concat(result, this._attr[a.substr(1)]);
      } else {
        result.push(a);
      }
    }

    return _.uniq(result);
  }

  _compileAttributesList(scheme) {
    let
      include = scheme.include ? this._expandAttributes(scheme.include) : this._attr.all,
      exclude = scheme.exclude ? this._expandAttributes(scheme.exclude) : [],
      result = [];

    for(let a of include) {
      if(exclude.indexOf(a) < 0) {
        result.push(a[0] != '.' && this._attr.all.indexOf(a) < 0 && this._attr.assoc.indexOf(a) < 0 ? '.' + a : a);
      }
    }

    return result;
  }

  _serializeValue(attr, value, cache) {
    const attributes = this._model.attributes || this._model.rawAttributes;
    const a = attributes[attr];
    let returnJSON = false;

    if(a && this._options.copyJSONFields) {
      returnJSON = (a.type instanceof this._seq.Sequelize.JSON || a.type instanceof this._seq.Sequelize.JSONB);
    }

    if(returnJSON) {

      return value;

    } else if(value instanceof Array) {

      let result = [];
      for(let e of value) {
        result.push(this._serializeValue(attr, e, cache));
      }
      return result;

    } else if(_isModelInstance(value, this._seq, this._seqVer)) {

      return this._serializeAssoc(attr, value, cache);

    } else {

      if(this._options.simpleDates && a && a.type instanceof this._seq.Sequelize.DATEONLY && value instanceof Date) {
        value = value.getFullYear() + '-' + _padWith0(value.getMonth() + 1) + '-' + _padWith0(value.getDate());
      }
      
      return this._options.encoder(value, this._options.encoderOptions);
    }
  }

  _serializeAssoc(attr, inst, cache) {
    let attrPath = (this._attrPath ? this._attrPath + '.' : '') + attr;
    let serializer;

    if(cache && cache[attrPath]) {
      serializer = cache[attrPath];
    } else {
      let scheme = this._scheme.assoc ? this._scheme.assoc[attr] : null;
      
      serializer = new Serializer(_getModelFromInstance(inst, this._seqVer), scheme, this._origOptions);
      serializer._attrPath = attrPath;

      if(cache) cache[attrPath] = serializer;
    }

    return serializer.serialize(inst, cache);
  }

  serialize(inst, cache) {
    if(!_isSpecificModelInstance(inst, this._model, this._seqVer)) {
      throw new Error('Not an instance of ' + this._model.name);
    }

    let output = {}, value, name;

    for(let a of this._attrList) {
      // if the attribute name is dot-prefixed, always treat it as a regular attribute of the model instance
      if(a[0] !== '.' && this._attr.all.indexOf(a) > -1) {
        value = inst.get(a);
      } else {
        if(a[0] === '.') a = a.substr(1);
          
        value = inst[a];
        if(typeof(value) === 'function') {
          value = value.call(inst);
        }
      }
        
      name = (this._scheme.as ? this._scheme.as[a] : null) || a;

      if(typeof(value) !== 'undefined') {
        output[name] = this._serializeValue(a, value, cache);
      } else {
        switch(this._options.undefinedPolicy) {
          case _policies.SKIP:
            break;
          case _policies.SET_NULL:
            output[name] = null;
            break;
          case _policies.FAIL:
            throw new Error('Undefined attribute on ' + this._model.name + ' instance: ' + a);
          default:
            throw new Error('Invalid undefinedPolicy setting');
        }
      }
    }

    if(this._model.serializer && this._model.serializer.postSerialize) {
      output = this._model.serializer.postSerialize.call(this._scheme, output, inst, this._schemeName);
    }
    
    if(this._scheme.postSerialize) {
      output = this._scheme.postSerialize(output, inst);
    }

    return output;
  }

  static serializeMany(data, model, scheme, options) {
    let serializer = new Serializer(model, scheme, options);
    let cache = {}, result = [];

    for(let inst of data) {
      result.push(serializer.serialize(inst, cache));
    }

    return result;
  }
}

for(let p in _policies) {
  Serializer[p] = _policies[p];
}

Serializer.encodeToJSON = encodeToJSON;
Serializer.defaultOptions = _defaultOptions;

module.exports = Serializer;