Angular - Advanced Patterns
You need to design a facade service that merges user profile data from UserService and application preferences from PreferencesService. Which implementation best follows the facade pattern?
You need to design a facade service that merges user profile data from UserService and application preferences from PreferencesService. Which implementation best follows the facade pattern?
hard📝 Conceptual Q8 of 15
Step-by-Step Solution
Solution:
Step 1: Understand facade responsibility
The facade should abstract and combine data sources for the component.Step 2: Analyze options
Create a facade service that exposes a combined observable usingcombineLatestfrom both services. usescombineLatestto merge observables, fitting the facade pattern.Step 3: Eliminate incorrect options
Inject both services into the component and merge data there instead of using a facade. moves logic to component, breaking abstraction; C exposes raw observables; D violates service encapsulation.Final Answer:
Create a facade service that exposes a combined observable using combineLatest from both services. -> Option AQuick Check:
Facade should combine and abstract data streams. [OK]
Quick Trick: Use combineLatest to merge observables in facade [OK]
Common Mistakes:
- Merging data in components instead of facade
- Exposing raw service observables without abstraction
- Modifying internal service data from facade
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