Method has

lib/associations/belongs-to-many.js:519–552

* Check if one or more instance(s) are associated with this. If a list of instances is passed, the function returns true if _all_ instances are associated * * @param {Model} sourceInstance source instance to check for an association with * @param {Model|Model[]|string[]|string|number[]|numb

(sourceInstance, instances, options)

   * @returns {Promise<boolean>}
   */
  async has(sourceInstance, instances, options) {
    if (!Array.isArray(instances)) {
      instances = [instances];
    }

    options = {
      raw: true,
      ...options,
      scope: false,
      attributes: [this.targetKey],
      joinTableAttributes: []
    };

    const instancePrimaryKeys = instances.map(instance => {
      if (instance instanceof this.target) {
        return instance.where();
      }
      return {
        [this.targetKey]: instance
      };
    });

    options.where = {
      [Op.and]: [
        { [Op.or]: instancePrimaryKeys },
        options.where
      ]
    };

    const associatedObjects = await this.get(sourceInstance, options);

    return _.differenceWith(instancePrimaryKeys, associatedObjects,
      (a, b) => _.isEqual(a[this.targetKey], b[this.targetKey])).length === 0;
  }

  /**
   * Set the associated models by passing an array of instances or their primary keys.