Source: DataStore.js

import utils from './utils'
import {
  belongsToType,
  hasManyType,
  hasOneType
} from './decorators'
import Container from './Container'
import LinkedCollection from './LinkedCollection'

const DOMAIN = 'DataStore'

const safeSet = function (record, field, value) {
  if (record && record._set) {
    record._set(field, value)
  } else {
    utils.set(record, field, value)
  }
}

const cachedFn = function (name, hashOrId, opts) {
  const self = this
  const cached = self._completedQueries[name][hashOrId]
  if (utils.isFunction(cached)) {
    return cached(name, hashOrId, opts)
  }
  return cached
}

const props = {
  constructor: function DataStore (opts) {
    const self = this
    utils.classCallCheck(self, DataStore)
    DataStore.__super__.call(self, opts)

    self.collectionClass = self.collectionClass || LinkedCollection
    self._collections = {}
    self._pendingQueries = {}
    self._completedQueries = {}
    return self
  },

  _callSuper (method, ...args) {
    return this.constructor.__super__.prototype[method].apply(this, args)
  },

  /**
   * TODO
   *
   * @name DataStore#_end
   * @method
   * @private
   * @param {string} name Name of the {@link LinkedCollection} to which to
   * add the data.
   * @param {Object} data TODO.
   * @param {Object} [opts] Configuration options.
   * @returns {(Object|Array)} Result.
   */
  _end (name, result, opts) {
    let _data = opts.raw ? result.data : result
    if (_data && utils.isFunction(this.addToCache)) {
      _data = this.addToCache(name, _data, opts)
      if (opts.raw) {
        result.data = _data
      } else {
        result = _data
      }
    }
    return result
  },

  /**
   * Register a new event listener on this DataStore.
   *
   * Proxy for {@link Container#on}. If an event was emitted by a Mapper or
   * Collection in the DataStore, then the name of the Mapper or Collection will
   * be prepended to the arugments passed to the provided event handler.
   *
   * @name DataStore#on
   * @method
   * @param {string} event Name of event to subsribe to.
   * @param {Function} listener Listener function to handle the event.
   * @param {*} [ctx] Optional content in which to invoke the listener.
   */

  /**
   * Used to bind to events emitted by collections in this store.
   *
   * @name DataStore#_onCollectionEvent
   * @method
   * @private
   * @param {string} name Name of the collection that emitted the event.
   * @param {...*} [args] Args passed to {@link Collection#emit}.
   */
  _onCollectionEvent (name, ...args) {
    const type = args.shift()
    this.emit(type, name, ...args)
  },

  /**
   * TODO
   *
   * @name DataStore#addToCache
   * @method
   * @param {string} name - Name of the {@link Mapper} to target.
   * @param {*} data - Data from which data should be selected for add.
   * @param {Object} [opts] - Configuration options.
   */
  addToCache (name, data, opts) {
    return this.getCollection(name).add(data, opts)
  },

  /**
   * Retrieve a cached `find` result, if any.
   *
   * @name DataStore#cachedFind
   * @method
   * @param {string} name The `name` argument passed to {@link DataStore#find}.
   * @param {(string|number)} id The `id` argument passed to {@link DataStore#find}.
   * @param {Object} opts The `opts` argument passed to {@link DataStore#find}.
   */
  cachedFind: cachedFn,

  /**
   * Retrieve a cached `findAll` result, if any.
   *
   * @name DataStore#cachedFindAll
   * @method
   * @param {string} name The `name` argument passed to {@link DataStore#findAll}.
   * @param {string} hash The result of calling {@link DataStore#hashQuery} on
   * the `query` argument passed to {@link DataStore#findAll}.
   * @param {Object} opts The `opts` argument passed to {@link DataStore#findAll}.
   */
  cachedFindAll: cachedFn,

  /**
   * Cache a `find` result. The default implementation does the following:
   *
   * ```
   * // Find and return the record from the data store
   * return this.get(name, id)
   * ```
   *
   * Override this method to customize.
   *
   * @name DataStore#cacheFind
   * @method
   * @param {string} name The `name` argument passed to {@link DataStore#find}.
   * @param {*} data The result to cache.
   * @param {(string|number)} id The `id` argument passed to {@link DataStore#find}.
   * @param {Object} opts The `opts` argument passed to {@link DataStore#find}.
   */
  cacheFind (name, data, id, opts) {
    const self = this
    self._completedQueries[name][id] = function (name, id, opts) {
      return self.get(name, id)
    }
  },

  /**
   * Cache a `findAll` result. The default implementation does the following:
   *
   * ```
   * // Find and return the records from the data store
   * return this.filter(name, utils.fromJson(hash))
   * ```
   *
   * Override this method to customize.
   *
   * @name DataStore#cacheFindAll
   * @method
   * @param {string} name The `name` argument passed to {@link DataStore#findAll}.
   * @param {*} data The result to cache.
   * @param {string} hash The result of calling {@link DataStore#hashQuery} on
   * the `query` argument passed to {@link DataStore#findAll}.
   * @param {Object} opts The `opts` argument passed to {@link DataStore#findAll}.
   */
  cacheFindAll (name, data, hash, opts) {
    const self = this
    self._completedQueries[name][hash] = function (name, hash, opts) {
      return self.filter(name, utils.fromJson(hash))
    }
  },

  /**
   * TODO
   *
   * @name DataStore#create
   * @method
   * @param {string} name Name of the {@link Mapper} to target.
   * @param {Object} record Passed to {@link Mapper#create}.
   * @param {Object} [opts] Passed to {@link Mapper#create}. See
   * {@link Mapper#create} for more configuration options.
   * @returns {Promise}
   */
  create (name, record, opts) {
    const self = this
    opts || (opts = {})
    return self._callSuper('create', name, record, opts).then(function (data) {
      return self._end(name, data, opts)
    })
  },

  /**
   * TODO
   *
   * @name DataStore#createMany
   * @method
   * @param {string} name Name of the {@link Mapper} to target.
   * @param {Array} records Passed to {@link Mapper#createMany}.
   * @param {Object} [opts] Passed to {@link Mapper#createMany}. See
   * {@link Mapper#createMany} for more configuration options.
   * @returns {Promise}
   */
  createMany (name, records, opts) {
    const self = this
    opts || (opts = {})
    return self._callSuper('createMany', name, records, opts).then(function (data) {
      return self._end(name, data, opts)
    })
  },

  defineMapper (name, opts) {
    const self = this
    const mapper = utils.getSuper(self).prototype.defineMapper.call(self, name, opts)
    self._pendingQueries[name] = {}
    self._completedQueries[name] = {}
    mapper.relationList || Object.defineProperty(mapper, 'relationList', { value: [] })

    // The datastore uses a subclass of Collection that is "datastore-aware"
    const collection = self._collections[name] = new self.collectionClass(null, { // eslint-disable-line
      // Make sure the collection has somewhere to store "added" timestamps
      _added: {},
      // Give the collection a reference to this datastore
      datastore: self,
      // The mapper tied to the collection
      mapper
    })

    const schema = mapper.schema || {}
    const properties = schema.properties || {}
    // TODO: Make it possible index nested properties?
    utils.forOwn(properties, function (opts, prop) {
      if (opts.indexed) {
        collection.createIndex(prop)
      }
    })

    // Create a secondary index on the "added" timestamps of records in the
    // collection
    collection.createIndex('addedTimestamps', ['$'], {
      fieldGetter (obj) {
        return collection._added[collection.recordId(obj)]
      }
    })

    collection.on('all', function (...args) {
      self._onCollectionEvent(name, ...args)
    })

    const idAttribute = mapper.idAttribute

    mapper.relationList.forEach(function (def) {
      const relation = def.relation
      const localField = def.localField
      const path = `links.${localField}`
      const foreignKey = def.foreignKey
      const type = def.type
      const updateOpts = { index: foreignKey }
      let descriptor

      const getter = function () { return this._get(path) }

      if (type === belongsToType) {
        if (!collection.indexes[foreignKey]) {
          collection.createIndex(foreignKey)
        }

        descriptor = {
          get: getter,
          set (record) {
            const _self = this
            const current = this._get(path)
            if (record === current) {
              return current
            }
            const id = utils.get(_self, idAttribute)
            const inverseDef = def.getInverse(mapper)

            if (record) {
              const relatedIdAttribute = def.getRelation().idAttribute
              const relatedId = utils.get(record, relatedIdAttribute)

              // Prefer store record
              if (!utils.isUndefined(relatedId)) {
                record = self.get(relation, relatedId) || record
              }

              // Set locals
              _self._set(path, record)
              safeSet(_self, foreignKey, relatedId)
              collection.updateIndex(_self, updateOpts)

              // Update (set) inverse relation
              if (inverseDef.type === hasOneType) {
                utils.set(record, inverseDef.localField, _self)
              } else if (inverseDef.type === hasManyType) {
                const children = utils.get(record, inverseDef.localField)
                utils.noDupeAdd(children, _self, function (_record) {
                  return id === utils.get(_record, idAttribute)
                })
              }
            } else {
              // Unset locals
              _self._set(path, undefined)
              safeSet(_self, foreignKey, undefined)
              collection.updateIndex(_self, updateOpts)
            }
            if (current) {
              if (inverseDef.type === hasOneType) {
                utils.set(current, inverseDef.localField, undefined)
              } else if (inverseDef.type === hasManyType) {
                const children = utils.get(current, inverseDef.localField)
                utils.remove(children, function (_record) {
                  return id === utils.get(_record, idAttribute)
                })
              }
            }
            return record
          }
        }

        if (mapper.recordClass.prototype.hasOwnProperty(foreignKey)) {
          const superClass = mapper.recordClass
          mapper.recordClass = superClass.extend({
            constructor: (function () {
              var subClass = function Record (props, opts) {
                utils.classCallCheck(this, subClass)
                superClass.call(this, props, opts)
              }
              return subClass
            })()
          })
        }
        Object.defineProperty(mapper.recordClass.prototype, foreignKey, {
          enumerable: true,
          get () { return this._get(foreignKey) },
          set (value) {
            const _self = this
            if (utils.isUndefined(value)) {
              // Unset locals
              utils.set(_self, localField, undefined)
            } else {
              safeSet(_self, foreignKey, value)
              let storeRecord = self.get(relation, value)
              if (storeRecord) {
                utils.set(_self, localField, storeRecord)
              }
            }
          }
        })
      } else if (type === hasManyType) {
        const localKeys = def.localKeys
        const foreignKeys = def.foreignKeys

        // TODO: Handle case when belongsTo relation isn't ever defined
        if (self._collections[relation] && foreignKey && !self.getCollection(relation).indexes[foreignKey]) {
          self.getCollection(relation).createIndex(foreignKey)
        }

        descriptor = {
          get () {
            const _self = this
            let current = getter.call(_self)
            if (!current) {
              _self._set(path, [])
            }
            return getter.call(_self)
          },
          set (records) {
            const _self = this
            records || (records = [])
            if (records && !utils.isArray(records)) {
              records = [records]
            }
            const id = utils.get(_self, idAttribute)
            const relatedIdAttribute = def.getRelation().idAttribute
            const inverseDef = def.getInverse(mapper)
            const inverseLocalField = inverseDef.localField
            let linked = _self._get(path)
            if (!linked) {
              linked = []
            }

            const current = linked
            linked = []
            const toLink = {}
            records.forEach(function (record) {
              const relatedId = utils.get(record, relatedIdAttribute)
              if (!utils.isUndefined(relatedId)) {
                // Prefer store record
                record = self.get(relation, relatedId) || record
                toLink[relatedId] = record
              }
              linked.push(record)
            })
            if (foreignKey) {
              records.forEach(function (record) {
                // Update (set) inverse relation
                safeSet(record, foreignKey, id)
                self.getCollection(relation).updateIndex(record, updateOpts)
                utils.set(record, inverseLocalField, _self)
              })
              current.forEach(function (record) {
                const relatedId = utils.get(record, relatedIdAttribute)
                if (!utils.isUndefined(relatedId) && !toLink.hasOwnProperty(relatedId)) {
                  // Update (unset) inverse relation
                  safeSet(record, foreignKey, undefined)
                  self.getCollection(relation).updateIndex(record, updateOpts)
                  utils.set(record, inverseLocalField, undefined)
                }
              })
            } else if (localKeys) {
              const _localKeys = []
              records.forEach(function (record) {
                // Update (set) inverse relation
                utils.set(record, inverseLocalField, _self)
                _localKeys.push(utils.get(record, relatedIdAttribute))
              })
              // Update locals
              utils.set(_self, localKeys, _localKeys)
              // Update (unset) inverse relation
              current.forEach(function (record) {
                const relatedId = utils.get(record, relatedIdAttribute)
                if (!utils.isUndefined(relatedId) && !toLink.hasOwnProperty(relatedId)) {
                  // Update inverse relation
                  utils.set(record, inverseLocalField, undefined)
                }
              })
            } else if (foreignKeys) {
              // Update (unset) inverse relation
              current.forEach(function (record) {
                const _localKeys = utils.get(record, foreignKeys) || []
                utils.remove(_localKeys, function (_key) {
                  return id === _key
                })
                const _localField = utils.get(record, inverseLocalField) || []
                utils.remove(_localField, function (_record) {
                  return id === utils.get(_record, idAttribute)
                })
              })
              // Update (set) inverse relation
              records.forEach(function (record) {
                const _localKeys = utils.get(record, foreignKeys) || []
                utils.noDupeAdd(_localKeys, id, function (_key) {
                  return id === _key
                })
                const _localField = utils.get(record, inverseLocalField) || []
                utils.noDupeAdd(_localField, _self, function (_record) {
                  return id === utils.get(_record, idAttribute)
                })
              })
            }

            _self._set(path, linked)
            return linked
          }
        }
      } else if (type === hasOneType) {
        // TODO: Handle case when belongsTo relation isn't ever defined
        if (self._collections[relation] && foreignKey && !self.getCollection(relation).indexes[foreignKey]) {
          self.getCollection(relation).createIndex(foreignKey)
        }
        descriptor = {
          get: getter,
          set (record) {
            const _self = this
            const current = this._get(path)
            if (record === current) {
              return current
            }
            const relatedId = utils.get(record, def.getRelation().idAttribute)
            const inverseLocalField = def.getInverse(mapper).localField
            // Update (unset) inverse relation
            if (current) {
              safeSet(current, foreignKey, undefined)
              self.getCollection(relation).updateIndex(current, updateOpts)
              utils.set(current, inverseLocalField, undefined)
            }
            if (record) {
              // Prefer store record
              if (!utils.isUndefined(relatedId)) {
                record = self.get(relation, relatedId) || record
              }

              // Set locals
              _self._set(path, record)

              // Update (set) inverse relation
              safeSet(record, foreignKey, utils.get(_self, idAttribute))
              self.getCollection(relation).updateIndex(record, updateOpts)
              utils.set(record, inverseLocalField, _self)
            } else {
              // Set locals
              _self._set(path, undefined)
            }
            return record
          }
        }
      }

      if (descriptor) {
        descriptor.enumerable = utils.isUndefined(def.enumerable) ? true : def.enumerable
        if (def.get) {
          let origGet = descriptor.get
          descriptor.get = function () {
            return def.get(def, this, (...args) => origGet.apply(this, args))
          }
        }
        if (def.set) {
          let origSet = descriptor.set
          descriptor.set = function (related) {
            return def.set(def, this, related, (value) => origSet.call(this, value === undefined ? related : value))
          }
        }
        Object.defineProperty(mapper.recordClass.prototype, localField, descriptor)
      }
    })

    return mapper
  },

  /**
   * TODO
   *
   * @name DataStore#destroy
   * @method
   * @param {string} name - Name of the {@link Mapper} to target.
   * @param {(string|number)} id - Passed to {@link Mapper#destroy}.
   * @param {Object} [opts] - Passed to {@link Mapper#destroy}. See
   * {@link Mapper#destroy} for more configuration options.
   * @returns {Promise}
   */
  destroy (name, id, opts) {
    const self = this
    opts || (opts = {})
    return self._callSuper('destroy', name, id, opts).then(function (data) {
      if (opts.raw) {
        data.data = self.getCollection(name).remove(id, opts)
      } else {
        data = self.getCollection(name).remove(id, opts)
      }
      delete self._pendingQueries[name][id]
      delete self._completedQueries[name][id]
      return data
    })
  },

  /**
   * TODO
   *
   * @name DataStore#destroyAll
   * @method
   * @param {string} name - Name of the {@link Mapper} to target.
   * @param {Object} [query] - Passed to {@link Mapper#destroyAll}.
   * @param {Object} [opts] - Passed to {@link Mapper#destroyAll}. See
   * {@link Mapper#destroyAll} for more configuration options.
   * @returns {Promise}
   */
  destroyAll (name, query, opts) {
    const self = this
    opts || (opts = {})
    return self._callSuper('destroyAll', name, query, opts).then(function (data) {
      if (opts.raw) {
        data.data = self.getCollection(name).removeAll(query, opts)
      } else {
        data = self.getCollection(name).removeAll(query, opts)
      }
      const hash = self.hashQuery(name, query, opts)
      delete self._pendingQueries[name][hash]
      delete self._completedQueries[name][hash]
      return data
    })
  },

  eject (id, opts) {
    return this.remove(id, opts)
  },

  ejectAll (query, opts) {
    return this.removeAll(query, opts)
  },

  /**
   * TODO
   *
   * @name DataStore#find
   * @method
   * @param {string} name - Name of the {@link Mapper} to target.
   * @param {(string|number)} id - Passed to {@link Mapper#find}.
   * @param {Object} [opts] - Passed to {@link Mapper#find}.
   * @returns {Promise}
   */
  find (name, id, opts) {
    const self = this
    opts || (opts = {})
    const pendingQuery = self._pendingQueries[name][id]

    utils.fillIn(opts, self.getMapper(name))

    if (pendingQuery) {
      return pendingQuery
    }
    const item = self.cachedFind(name, id, opts)
    let promise

    if (opts.force || !item) {
      promise = self._pendingQueries[name][id] = self._callSuper('find', name, id, opts).then(function (data) {
        delete self._pendingQueries[name][id]
        const result = self._end(name, data, opts)
        self.cacheFind(name, result, id, opts)
        return result
      }, function (err) {
        delete self._pendingQueries[name][id]
        return utils.reject(err)
      })
    } else {
      promise = utils.resolve(item)
    }
    return promise
  },

  /**
   * TODO
   *
   * @name DataStore#findAll
   * @method
   * @param {string} name - Name of the {@link Mapper} to target.
   * @param {Object} [query] - Passed to {@link Model.findAll}.
   * @param {Object} [opts] - Passed to {@link Model.findAll}.
   * @returns {Promise}
   */
  findAll (name, query, opts) {
    const self = this
    opts || (opts = {})
    const hash = self.hashQuery(name, query, opts)
    const pendingQuery = self._pendingQueries[name][hash]

    utils.fillIn(opts, self.getMapper(name))

    if (pendingQuery) {
      return pendingQuery
    }

    const items = self.cachedFindAll(name, hash, opts)
    let promise

    if (opts.force || !items) {
      promise = self._pendingQueries[name][hash] = self._callSuper('findAll', name, query, opts).then(function (data) {
        delete self._pendingQueries[name][hash]
        const result = self._end(name, data, opts)
        self.cacheFindAll(name, result, hash, opts)
        return result
      }, function (err) {
        delete self._pendingQueries[name][hash]
        return utils.reject(err)
      })
    } else {
      promise = utils.resolve(items)
    }
    return promise
  },

  /**
   * TODO
   *
   * @name DataStore#getCollection
   * @method
   * @param {string} name Name of the {@link LinkedCollection} to retrieve.
   * @returns {LinkedCollection}
   */
  getCollection (name) {
    const collection = this._collections[name]
    if (!collection) {
      throw utils.err(`${DOMAIN}#getCollection`, name)(404, 'collection')
    }
    return collection
  },

  hashQuery (name, query, opts) {
    return utils.toJson(query)
  },

  inject (records, opts) {
    return this.add(records, opts)
  },

  remove (name, id, opts) {
    const self = this
    const record = self.getCollection(name).remove(id, opts)
    if (record) {
      self.removeRelated(name, [record], opts)
    }
    return record
  },

  removeAll (name, query, opts) {
    const self = this
    const records = self.getCollection(name).removeAll(query, opts)
    if (records.length) {
      self.removeRelated(name, records, opts)
    }
    return records
  },

  removeRelated (name, records, opts) {
    const self = this
    utils.forEachRelation(self.getMapper(name), opts, function (def, optsCopy) {
      records.forEach(function (record) {
        let relatedData
        let query
        if (def.foreignKey && (def.type === hasOneType || def.type === hasManyType)) {
          query = { [def.foreignKey]: def.getForeignKey(record) }
        } else if (def.type === hasManyType && def.localKeys) {
          query = {
            where: {
              [def.getRelation().idAttribute]: {
                'in': utils.get(record, def.localKeys)
              }
            }
          }
        } else if (def.type === hasManyType && def.foreignKeys) {
          query = {
            where: {
              [def.foreignKeys]: {
                'contains': def.getForeignKey(record)
              }
            }
          }
        } else if (def.type === belongsToType) {
          relatedData = self.remove(def.relation, def.getForeignKey(record), optsCopy)
        }
        if (query) {
          relatedData = self.removeAll(def.relation, query, optsCopy)
        }
        if (relatedData) {
          if (utils.isArray(relatedData) && !relatedData.length) {
            return
          }
          if (def.type === hasOneType) {
            relatedData = relatedData[0]
          }
          def.setLocalField(record, relatedData)
        }
      })
    })
  },

  /**
   * TODO
   *
   * @name DataStore#update
   * @method
   * @param {string} name - Name of the {@link Mapper} to target.
   * @param {(string|number)} id - Passed to {@link Mapper#update}.
   * @param {Object} record - Passed to {@link Mapper#update}.
   * @param {Object} [opts] - Passed to {@link Mapper#update}. See
   * {@link Mapper#update} for more configuration options.
   * @returns {Promise}
   */
  update (name, id, record, opts) {
    const self = this
    opts || (opts = {})
    return self._callSuper('update', name, id, record, opts).then(function (data) {
      return self._end(name, data, opts)
    })
  },

  /**
   * TODO
   *
   * @name DataStore#updateAll
   * @method
   * @param {string} name - Name of the {@link Mapper} to target.
   * @param {Object} props - Passed to {@link Mapper#updateAll}.
   * @param {Object} [query] - Passed to {@link Mapper#updateAll}.
   * @param {Object} [opts] - Passed to {@link Mapper#updateAll}. See
   * {@link Mapper#updateAll} for more configuration options.
   * @returns {Promise}
   */
  updateAll (name, props, query, opts) {
    const self = this
    opts || (opts = {})
    return self._callSuper('updateAll', name, query, props, opts).then(function (data) {
      return self._end(name, data, opts)
    })
  },

  /**
   * TODO
   *
   * @name DataStore#updateMany
   * @method
   * @param {string} name Name of the {@link Mapper} to target.
   * @param {(Object[]|Record[])} records Passed to {@link Mapper#updateMany}.
   * @param {Object} [opts] Passed to {@link Mapper#updateMany}. See
   * {@link Mapper#updateMany} for more configuration options.
   * @returns {Promise}
   */
  updateMany (name, records, opts) {
    const self = this
    opts || (opts = {})
    return self._callSuper('updateMany', name, records, opts).then(function (data) {
      return self._end(name, data, opts)
    })
  }
}

const toProxy = [
  'add',
  'between',
  'createIndex',
  'filter',
  'get',
  'getAll',
  'query',
  'toJson'
]

toProxy.forEach(function (method) {
  props[method] = function (name, ...args) {
    return this.getCollection(name)[method](...args)
  }
})

/**
 * The `DataStore` class is an extension of {@link Container}. Not only does
 * `DataStore` manage mappers, but also collections. `DataStore` implements the
 * asynchronous {@link Mapper} methods, such as {@link Mapper#find} and
 * {@link Mapper#create}. If you use the asynchronous `DataStore` methods
 * instead of calling them directly on the mappers, then the results of the
 * method calls will be inserted into the store's collections. You can think of
 * a `DataStore` as an [Identity Map](https://en.wikipedia.org/wiki/Identity_map_pattern)
 * for the [ORM](https://en.wikipedia.org/wiki/Object-relational_mapping)
 * (the Mappers).
 *
 * ```javascript
 * import {DataStore} from 'js-data'
 * ```
 *
 * @example
 * import {DataStore} from 'js-data'
 * import HttpAdapter from 'js-data-http'
 * const store = new DataStore()
 * const UserMapper = store.defineMapper('user')
 *
 * // Call "find" on "UserMapper" (Stateless ORM)
 * UserMapper.find(1).then((user) => {
 *   // retrieved a "user" record via the http adapter, but that's it
 *
 *   // Call "find" on "store" targeting "user" (Stateful DataStore)
 *   return store.find('user', 1)
 * }).then((user) => {
 *   // not only was a "user" record retrieved, but it was added to the
 *   // store's "user" collection
 *   const cachedUser = store.getCollection('user').get(1)
 *   console.log(user === cachedUser) // true
 * })
 *
 * @class DataStore
 * @extends Container
 * @param {Object} [opts] Configuration options. See {@link Container}.
 * @returns {DataStore}
 * @see Container
 * @since 3.0.0
 * @tutorial ["http://www.js-data.io/v3.0/docs/components-of-jsdata#datastore","Components of JSData: DataStore"]
 * @tutorial ["http://www.js-data.io/v3.0/docs/working-with-the-datastore","Working with the DataStore"]
 * @tutorial ["http://www.js-data.io/v3.0/docs/jsdata-and-the-browser","Notes on using JSData in the Browser"]
 */
export default Container.extend(props)

/**
 * Create a subclass of this DataStore.
 *
 * @example <caption>Extend the class in a cross-browser manner.</caption>
 * import {DataStore} from 'js-data'
 * const CustomDataStoreClass = DataStore.extend({
 *   foo () { return 'bar' }
 * })
 * const customDataStore = new CustomDataStoreClass()
 * console.log(customDataStore.foo()) // "bar"
 *
 * @example <caption>Extend the class using ES2015 class syntax.</caption>
 * class CustomDataStoreClass extends DataStore {
 *   foo () { return 'bar' }
 * }
 * const customDataStore = new CustomDataStoreClass()
 * console.log(customDataStore.foo()) // "bar"
 *
 * @method DataStore.extend
 * @param {Object} [props={}] Properties to add to the prototype of the
 * subclass.
 * @param {Object} [classProps={}] Static properties to add to the subclass.
 * @returns {Constructor} Subclass of this DataStore.
 * @since 3.0.0
 */