proxy get method for db record in cache

proxyGetDBRecord.js

Cache.proxyGetDBRecord = function *(model, id, field) {
  if (!id) {
    return null;
  }
  let key = genCacheKeyWithModel(model, id); // generate id with tableName and id
  let result = null;
  
  if (field) {
    result = yield client.hgetAsync(key, field);
  } else {
    result = yield client.hgetallAsync(key);
  }

  if (result === null) {
    let fields = model.getCacheFields();

    if (field && fields.indexOf(field) === -1) {
      fields.push(field);
    }
    let data = yield model.findOne({
      where: {id: id},
      attributes: fields,
      raw: true
    });
    if (data) {
      yield client.hmsetAsync(key, data);
      yield client.expireAsync(key, constant.CACHE_EXPIRE_TIME);
      result = field? data[field]: data;
    }
  }
  return result;
}