ice-db/collection.js

In-memory DB

const {
  Object
} = require('./object');

class Collection {
  /**
   *Creates an instance of Collection.
   * @param {*} {
   *     name
   *   }
   * @memberof Collection
   */
  constructor({
    name
  }) {
    this.name = name;
    this.data = []
  }

  /**
   *Checks if an id of an object is defined
   *
   * @param {Object} object object to check
   * @throws error if id is undefined
   * @memberof Collection
   */
  _checkIdDefined(object) {
    if (!object.id) {
      throw {
        code: 400,
        message: 'ID is undefined',
        object
      }
    }
  }

  /**
   *Checks if a rev of an object is defined
   *
   * @param {Object} object object to check
   * @throws error if rev is undefined
   * @memberof Collection
   */
  _checkRevDefined(object) {
    if (!object.rev) {
      throw {
        code: 400,
        message: 'Rev is undefined',
        object
      }
    }
  }
  /**
   *Checks if rev is valid
   *
   * @param {*} objectOne An object which is given by a user
   * @param {*} objectTwo An object with a valid rev
   * @memberof Collection
   * @throws error if rev is not valid
   */
  _checkRevValid(objectOne, objectTwo) {
    if (!(objectOne.rev === objectTwo.rev)) {
      throw {
        code: 409,
        message: `Conflict: revision number ${object.rev} is not latest`
      }
    }
  }

  /**
   *Clears all data in this collection
   *
   * @memberof Collection
   */
  drop() {
    this.data = []
    delete this
  }

  /**
   *Inserts a new object ino collection
   *
   * @param {*} object object to create
   * @returns {Object} created object
   * @memberof Collection
   */
  insert(object) {
    let newObject = new Object(object)
    this.data.push(newObject)
    return newObject
  }

  /**
   *Gets an object from the colection by a given id
   *
   * @param {String} id id of an object
   * @returns {Object} an objet with a given id
   * @memberof Collection
   */
  get(id) {
    return this.data[this._getIndexInData(id)]
  }

  /**
   *Gets all objects in a collection
   *
   * @returns {[Object]} all objects in a collection
   * @memberof Collection
   */
  list() {
    return this.data
  }

  /**
   *Returns an index in data array by a given object id
   *
   * @param {String} id id of an object
   * @returns {Number} an index
   * @throws error if id is not defined
   * @throws error if index is not found
   * @memberof Collection
   */
  _getIndexInData(id) {
    if (!id) {
      throw {
        code: 400,
        message: `Id is not defined`
      }
    }
    let index
    this.data.forEach((obj, i) => {
      if (obj.id === id) {
        index = i
      }
    })
    if (typeof index === 'undefined') {
      throw {
        code: 404,
        message: `Object with id "${id}" is not found`
      }
    }
    return index
  }

  /**
   *Deletes an object from the collection without any checks
   *
   * @param {Object} object an object to delete
   * @memberof Collection
   */
  _forceDelete(object) {
    let index = this._getIndexInData(object.id)
    this.data.splice(index, 1)
  }

  /**
   * Deletes an object from the collection
   * @param {Object} object an object to delete
   * @memberof Collection
   */
  delete(object) {
    // first check whether a given object is actually an object of the collection
    this._checkIdDefined(object)
    this._checkRevDefined(object)
    // retreive an object which should be deleted
    let oldObject = this.get(object.id)
    // check if revision number is the valid one
    this._checkRevValid(object, oldObject)
    // delete an object
    this._forceDelete(oldObject);
  }

  /**
   * Updates a given object
   * @param {Object} object with updated params
   * @returns {Object} an updated object
   */
  update(object) {
    // deletes object (with all checks)
    this.delete(object)
    // increments rev number according to rules
    object._incrementRev()
    this.insert(object)
    return object
  }

}

module.exports = {
  Collection
}