Which is the best way to implement this service-to-service injection pattern?
hard🚀 Application Q15 of 15
Angular - Services and Dependency Injection
You have two services: ApiService and CacheService. You want ApiService to use CacheService to store data before returning it. Which is the best way to implement this service-to-service injection pattern?
AInject CacheService into ApiService constructor and call cache methods inside ApiService
BInject ApiService into CacheService and call API methods inside CacheService
CCreate a third service that duplicates both ApiService and CacheService methods
DUse global variables to share data between ApiService and CacheService
Step-by-Step Solution
Solution:
Step 1: Understand service responsibilities
ApiService handles API calls, CacheService handles data storage. ApiService should use CacheService to store data.
Step 2: Apply service-to-service injection
Inject CacheService into ApiService's constructor, then call CacheService methods inside ApiService to store data before returning it.
Step 3: Avoid bad patterns
Injecting ApiService into CacheService or duplicating methods breaks separation of concerns. Using global variables is bad practice.
Final Answer:
Inject CacheService into ApiService constructor and call cache methods inside ApiService -> Option A
Quick Check:
Inject dependent service into main service for clean logic [OK]
Quick Trick:Inject helper service into main service, not vice versa [OK]
Common Mistakes:
MISTAKES
Injecting main service into helper service causing circular dependency
Duplicating logic instead of reusing services
Using global variables instead of injection
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