golang mongo-driver Aggregate

分组计算

// ListGroupByUser group by user
func (repo PostReadRepository) ListGroupByUser(postUID string) (list []*model.PostRead, err error) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	pipeline := []bson.M{bson.M{"$group": bson.M{"_id": bson.M{"postuid": "$postuid", "createdby": "$createdby"},
		"createdon": bson.M{"$max": "$createdon.t"}, "uid": bson.M{"$max": "$_id"}, "readtime": bson.M{"$sum": "$readtime"}}}}
	opts := options.Aggregate()
	cur, err := dbPostRead.Aggregate(ctx, pipeline, opts)
	defer cur.Close(ctx)

	for cur.Next(ctx) {
		var doc map[string]interface{}
		cur.Decode(&doc)
		createdOn, _ := time.ParseInLocation("2006-01-02T15:04:05", doc["createdon"].(string), time.Local)
		read := &model.PostRead{
			UID:       doc["uid"].(string),
			PostUID:   doc["_id"].(map[string]interface{})["postuid"].(string),
			ReadTime:  doc["readtime"].(int64),
			CreatedOn: mask.Timestamp{Time: createdOn},
			CreatedBy: doc["_id"].(map[string]interface{})["createdby"].(string),
		}
		read.User = proxy.GetUserInfo(read.CreatedBy)

		list = append(list, read)
	}
	return
}