Method updateAssociations

lib/associations/belongs-to-many.js:584–649

    };

    const updateAssociations = currentRows => {
      const obsoleteAssociations = [];
      const promises = [];
      const defaultAttributes = options.through || {};

      const unassociatedObjects = newAssociatedObjects.filter(obj =>
        !currentRows.some(currentRow => currentRow[foreignIdentifier] === obj.get(targetKey))
      );

      for (const currentRow of currentRows) {
        const newObj = newAssociatedObjects.find(obj => currentRow[foreignIdentifier] === obj.get(targetKey));

        if (!newObj) {
          obsoleteAssociations.push(currentRow);
        } else {
          let throughAttributes = newObj[this.through.model.name];
          // Quick-fix for subtle bug when using existing objects that might have the through model attached (not as an attribute object)
          if (throughAttributes instanceof this.through.model) {
            throughAttributes = {};
          }

          const attributes = { ...defaultAttributes, ...throughAttributes };

          if (Object.keys(attributes).length) {
            promises.push(
              this.through.model.update(attributes, Object.assign(options, {
                where: {
                  [identifier]: sourceInstance.get(sourceKey),
                  [foreignIdentifier]: newObj.get(targetKey)
                }
              }
              ))
            );
          }
        }
      }

      if (obsoleteAssociations.length > 0) {
        promises.push(
          this.through.model.destroy({
            ...options,
            where: {
              [identifier]: sourceInstance.get(sourceKey),
              [foreignIdentifier]: obsoleteAssociations.map(obsoleteAssociation => obsoleteAssociation[foreignIdentifier]),
              ...this.through.scope
            }
          })
        );
      }

      if (unassociatedObjects.length > 0) {
        const bulk = unassociatedObjects.map(unassociatedObject => {
          return {
            ...defaultAttributes,
            ...unassociatedObject[this.through.model.name],
            [identifier]: sourceInstance.get(sourceKey),
            [foreignIdentifier]: unassociatedObject.get(targetKey),
            ...this.through.scope