Base.js

// models/Base.js

class Base {
  constructor(args) {
    const results = this.validatedData(args);
    Object.assign(this, results);
  }

  get schema() {
    throw ('You must declare a schema');
  }

  // Return the collection name that corresponds to Firestore
  // Method should be overwritten in child models
  get collectionName() {
    return this.constructor.collectionName();
  }

  // Returns the expected schema of the model
  expectedSchema() {
    // stripUnknown will remove any properties that aren't on the schema
    return Joi.object().keys(this.schema).options({ stripUnknown: true });
  }

  // Return validated fields
  validatedData(args) {
    const { error, value } = Joi.validate(args, this.expectedSchema());
    if (error) {
      throw new Error(error);
    }
    return value;
  }

  async create() {
    ...
  }

  async save() {
    ...
  }

  static async findById(id) {
    ...
  }

  static async findAll() {
    ...
  }

  ...
};