Clean Architecture layers in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to name the innermost layer of Clean Architecture.

LLD

The innermost layer in Clean Architecture is called the [1] layer.

Drag options to blanks, or click blank then click option'

AEntities

BGateways

CControllers

DPresenters

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing Entities with outer layers like Controllers or Presenters.

The Entities layer contains the core business rules and is the innermost layer in Clean Architecture.

2fill in blank

medium

Complete the code to name the layer responsible for application-specific business rules.

LLD

The layer that contains application-specific business rules is called the [1] layer.

Drag options to blanks, or click blank then click option'

AFrameworks

BEntities

CUI

DUse Cases

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing Use Cases with Entities or UI layers.

The Use Cases layer contains application-specific business rules and orchestrates the flow of data to and from the Entities.

3fill in blank

hard

Fix the error in naming the outermost layer that interacts with external systems.

LLD

The outermost layer in Clean Architecture is the [1] layer.

Drag options to blanks, or click blank then click option'

AFrameworks and Drivers

BInterface Adapters

CEntities

DUse Cases

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing Interface Adapters with the outermost layer.

The Frameworks and Drivers layer is the outermost layer and contains details like UI, database, and external interfaces.

4fill in blank

hard

Fill both blanks to complete the description of the Interface Adapters layer.

LLD

The Interface Adapters layer converts data from the [1] layer to the [2] layer format.

Drag options to blanks, or click blank then click option'

AEntities

BFrameworks and Drivers

CUse Cases

DUI

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of layers or confusing Entities with Frameworks.

The Interface Adapters layer converts data from the Frameworks and Drivers layer to the Use Cases layer format and vice versa.

5fill in blank

hard

Fill all three blanks to complete the dependency rule in Clean Architecture.

LLD

In Clean Architecture, dependencies always point inward from [1] to [2], and the outer layers depend on the [3] layers.

Drag options to blanks, or click blank then click option'

AFrameworks and Drivers

BEntities

CUse Cases

DInterface Adapters

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the direction of dependencies or mixing up layer names.

Dependencies point inward from Frameworks and Drivers to Interface Adapters, and outer layers depend on the Entities layer.

Practice

1. Which layer in Clean Architecture contains the core business rules and logic?

easy

A. UI layer

B. Entities layer

C. Database layer

D. Frameworks layer

Solution

1. Step 1: Understand the role of each layer

   The Entities layer holds the core business rules and logic, independent of external concerns.

2. Step 2: Identify the correct layer for business logic

   UI, Database, and Frameworks layers handle external interactions, not core logic.

3. Final Answer:

   Entities layer -> Option B

4. Quick Check:

   Business logic = Entities layer [OK]

Hint: Core logic always lives in the Entities layer [OK]

Common Mistakes:

• Confusing UI layer with business logic
• Thinking database layer contains core rules
• Mixing frameworks with core logic

2. In Clean Architecture, which layer is responsible for adapting data from the database to the business logic?

easy

A. Entities layer

B. Use Cases (Interactor) layer

C. UI layer

D. Interface Adapters layer

Solution

1. Step 1: Identify the role of Interface Adapters

   Interface Adapters convert data from external sources like databases into a form usable by inner layers.

2. Step 2: Confirm other layers' roles

   Entities hold business rules, Use Cases orchestrate logic, UI handles presentation, so adapting data fits Interface Adapters.

3. Final Answer:

   Interface Adapters layer -> Option D

4. Quick Check:

   Data adaptation = Interface Adapters [OK]

Hint: Data conversion happens in Interface Adapters [OK]

Common Mistakes:

• Choosing Entities layer for data adaptation
• Confusing Use Cases with data conversion
• Selecting UI layer for database data handling

3. Given the following flow in Clean Architecture: UI calls Use Cases, which then call Entities. What is the correct order of dependency direction?

medium

A. UI -> Entities -> Use Cases

B. Entities -> Use Cases -> UI

C. UI -> Use Cases -> Entities

D. Use Cases -> UI -> Entities

Solution

1. Step 1: Understand dependency rule in Clean Architecture

   Dependencies always point inward, from outer layers to inner layers.

2. Step 2: Apply to given flow

   UI depends on Use Cases, which depend on Entities, so direction is UI -> Use Cases -> Entities.

3. Final Answer:

   UI -> Use Cases -> Entities -> Option C

4. Quick Check:

   Dependency direction = UI to Entities [OK]

Hint: Dependencies always point inward [OK]

Common Mistakes:

• Reversing dependency direction
• Confusing which layer calls which
• Assuming Entities depend on UI

4. A developer placed database access code directly inside the Entities layer. What is the main problem with this design?

medium

A. Entities layer should not depend on external frameworks or databases

B. Entities layer must handle UI rendering

C. Database code belongs only in the UI layer

D. Entities layer should only contain database schemas

Solution

1. Step 1: Recall Clean Architecture dependency rules

   Inner layers like Entities must be independent of external concerns like databases.

2. Step 2: Identify why database code in Entities is wrong

   It creates tight coupling and breaks separation of concerns.

3. Final Answer:

   Entities layer should not depend on external frameworks or databases -> Option A

4. Quick Check:

   Entities layer independence = true [OK]

Hint: Keep Entities free from external dependencies [OK]

Common Mistakes:

• Thinking Entities handle UI
• Placing database code in UI layer
• Confusing database schemas with business logic

5. You need to design a system where the UI can be changed without affecting business rules, and the database can be swapped easily. Which Clean Architecture principle helps achieve this?

hard

A. Dependency Rule: Inner layers do not depend on outer layers

B. UI layer directly accesses Entities for faster updates

C. Database layer contains business logic for flexibility

D. Use Cases layer handles UI rendering and database access

Solution

1. Step 1: Identify the principle for independence

   The Dependency Rule states inner layers (business rules) do not depend on outer layers (UI, database).

2. Step 2: Explain how this helps system flexibility

   This separation allows changing UI or database without impacting core business logic.

3. Final Answer:

   Dependency Rule: Inner layers do not depend on outer layers -> Option A

4. Quick Check:

   Dependency Rule ensures flexibility [OK]

Hint: Inner layers must be independent for easy changes [OK]

Common Mistakes:

• Allowing UI to access Entities directly
• Putting business logic in database layer
• Mixing UI rendering with Use Cases