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golang database layer with cache
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| type CacheInterface interface { | |
| Get(key string) ([]byte, error) | |
| Set(key string, value interface{}) error | |
| } | |
| // Cache implements CacheInterface. | |
| type Cache struct { | |
| // wrap redis pool connection | |
| // or whatever you need | |
| } | |
| func (c *Cache) Get(key string) ([]byte, error) { | |
| // get data from redis | |
| return b, nil | |
| } | |
| func (c *Cache) Set(key string, value interface{}) error { | |
| // save data to redis | |
| return nil | |
| } |
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| type DatabaseInterface interface { | |
| GetFollowers(userID string) ([]models.User, error) | |
| } | |
| type Database struct { | |
| // wrap sql connection | |
| // or any other driver that your database needs | |
| } | |
| func (db *Database) GetFollowers(userID string) ([]models.User, error) { | |
| // get users from db | |
| // can be any db, e.g. PostgreSQL, CouchDB, MongoDB | |
| return users, nil | |
| } |
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| // handler gets followers through database wrapper | |
| // the wrapper checks the cache first and then checks the database | |
| func(w http.ResponseWriter, r *http.Request) { | |
| // get user from url | |
| users, err := wrapper.GetFollowers(user.ID) | |
| if err != nil { | |
| // return err | |
| } | |
| // do something with users | |
| } | |
| // handler needs access to pure caching and/or database methods | |
| func(w http.ResponseWriter, r *http.Request) { | |
| cache := wrapper.GetCache() | |
| // do something that cache provides but that the wrapper does not | |
| b, err := cache.Get("some:key") | |
| if err != nil { | |
| // return err | |
| } | |
| // do something with b | |
| } |
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| type WrapperInterface interface { | |
| GetFollowers(userID string) ([]models.User, error) | |
| // sometimes I need access to the pure db and/or cache | |
| GetCache() CacheInterface | |
| GetDB() DatabaseInterface | |
| } | |
| // Wrapper implements WrapperInterface. | |
| type Wrapper struct { | |
| Cache CacheInterface | |
| Database DatabaseInterface | |
| } | |
| func (w *Wrapper) GetCache() CacheInterface { | |
| return w.Cache | |
| } | |
| func (w *Wrapper) GetDatabase() DatabaseInterface { | |
| return w.Database | |
| } | |
| func (w *Wrapper) GetFollowers(userID string) ([]models.User, err) { | |
| // check cache first | |
| b, err := db.Cache.Get("key") | |
| if err != nil && err != redis.ErrNil { | |
| return nil, err | |
| } | |
| // if chache does not have any data get it from database | |
| if err == redis.ErrNil { | |
| data, err := db.Database.GetFollowers(userID) | |
| if err != nil { | |
| return nil, err | |
| } | |
| // add data to cache | |
| if err := db.Cache.Set(key, result); err != nil { | |
| return nil, err | |
| } | |
| return result, nil | |
| } | |
| // return data from cache | |
| var result []models.User | |
| if err := json.Unmarshal(b, &result); err != nil { | |
| return nil, err | |
| } | |
| return result, nil | |
| } |
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