schase.js

function schase(models, objects = {}) {  
  function resolve(data) {
    for(const [ name, object ] of Object.entries(data)) {
      const [ _,  base, ref ] = /(.*?)(_id|Id|Ids|_ids)?$/.exec(name)

      const [ plural ] = /es|s$/.exec(ref) || []

      const model = base.replace(/es|s$/, '')

      if(!objects[model]) objects[model] = {}

      const instances = objects[model]

      if(ref) {
        if(plural) {
          Object.defineProperty(data, model+plural, {
            get() {
              return this[name].map(id => instances[id])
            }
          })
        } else {
          Object.defineProperty(data, model, {
            get() {
              return instances[this[name]]
            }
          })
        }        
      } else if(object && typeof object === 'object') {  
        function mapInstance(value) {
          if(!(value && typeof value === 'object')) return value
          if(!('id' in value || '_id' in value)) return value
          const id = value.id || value._id
          const instance = instances[id] || value
          instances[id] = Object.assign(value, instance)
          resolve(value, objects)
          return instances[id]
        }

        data[name] = Array.isArray(object) ? object.map(mapInstance) : mapInstance(object)
      }
    }
    return data
  }

  return resolve(models)
}