better-buddy-share-backend
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    Class UserCacheDao

    Base abstraction for DAOs that use a caching layer.

    Provides helper methods to interact with CacheService and maps underlying cache errors into DaoError subclasses.

    Hierarchy (View Summary)

    Index

    Constructors

    constructor

    Properties

    cacheService

    Methods

    cacheDel cacheGet cacheMGet cacheSet deleteUser findByEmail findById mapCacheError upsertUser

    Constructors

    Properties

    cacheService: CacheService

    Instance of the CacheService used to perform cache operations.

    Methods

    • Get a value from cache by key.

      Returns null when the key does not exist.

      Type Parameters

      • T

        Expected type of the cached value.

      Parameters

      • key: string

        Cache key to read.

      Returns Promise<T | null>

      The value stored under the key or null if not present.

      DaoError when a cache-related error occurs.

    • Get multiple values from cache by an array of keys.

      If the underlying CacheService does not provide a batch get, this method falls back to parallel single gets.

      Type Parameters

      • T

        Expected type of each cached value.

      Parameters

      • keys: string[]

        Array of cache keys to read.

      Returns Promise<(T | null)[]>

      An array containing the values or nulls for missing keys.

      DaoError when a cache-related error occurs.

    • Set a value in cache with optional TTL.

      Type Parameters

      • T

        Type of the value to store.

      Parameters

      • key: string

        Cache key to set.

      • value: T

        Value to store.

      • OptionalttlSeconds: number

        Optional time-to-live in seconds.

      Returns Promise<void>

      DaoError when a cache-related error occurs.

    • Removes a user from Redis cache

      • Removes user entry from cache under key user:${id}
      • Uses CacheService.del() for consistent error handling
      • Logs information about user removal

      Parameters

      • id: number

        User ID to remove from cache

      Returns Promise<void>

      Error when Redis deletion problem occurs

      await userCache.deleteUser(123);
      console.log('User removed from cache');

      CacheService.del

    • Searches for a user in Redis cache by email address

      • First fetches user ID from key user:email:${email}
      • Then calls findById() to fetch complete user data
      • Logs cache hit/miss information for email searches
      • Uses two-step lookup: email -> user_id -> user data

      Parameters

      • email: string

        User email address to search for

      Returns Promise<User | null>

      Promise resolving to user object or null if not found

      Error when Redis connection problem occurs

      const user = await userCache.findByEmail('user@example.com');
      if (user) {
        console.log(`Found user with ID: ${user.user_id}`);
      }

      findById

    • Searches for a user in Redis cache by ID

      • Fetches user from cache under key user:${id}
      • Automatically converts date strings to Date objects (created_at, ban_expires_at)
      • Logs cache hit/miss information for debugging purposes
      • Uses CacheService for consistent error handling

      Parameters

      • id: number

        User ID to search for

      Returns Promise<User | null>

      Promise resolving to user object or null if not found

      Error when Redis connection problem occurs

      const user = await userCache.findById(123);
      if (user) {
        console.log(`Found user: ${user.username}`);
      }

      CacheService.get

    • Creates or updates a user in Redis cache

      • Checks if user already exists in cache using findById()
      • If exists and data is identical (comparison via lodash.isEqual), skips update
      • If exists but data differs, removes old entry and creates new one
      • Saves user under key user:${id} and creates mapping user:email:${email} -> user_id
      • Sets cache expiration to 1 hour (3600 seconds) for both keys
      • Uses Promise.all() for parallel Redis operations

      Parameters

      • user: User

        User object to save in cache

      Returns Promise<User>

      Promise resolving to the user object (same as passed)

      Error when Redis write problem occurs

      const userData = {
        user_id: 123,
        username: 'john_doe',
        email: 'john@example.com',
        created_at: new Date()
      };

      const cachedUser = await userCache.upsertUser(userData);
      console.log('User cached successfully:', cachedUser.username);

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