Code smells/refactored to remove broken hierarchy code smell, long method ,decompose conditional and introduce explaining variable

[DhRuva-1509]

Refactoring Summary for MigrationManager.java and StringFilter.java

Overview

This document summarizes the refactoring of two files in the Nitrite Java project (forked repository): MigrationManager.java and StringFilter.java. For MigrationManager.java, the doMigrate method was refactored using Set I techniques (Extract Method, Decompose Conditional, Introduce Explaining Variable) to address "Long Method" and "Complex Conditional Logic" smells. For StringFilter.java, the class was refactored to fix a "Broken Hierarchy" smell using Set II techniques (Pull-up Method, Extract Class, Replace Conditional with Polymorphism). These changes enhance readability and maintainability while preserving functionality, ensuring the code compiles, passes tests, and is ready for a pull request to Nitrite Java by March 29, 2025.

File Information

• File 1: org.dizitart.no2.migration.MigrationManager.java
  • Location: MigrationManager.java
  • Purpose: Manages schema migrations for the Nitrite database.
• File 2: org.dizitart.no2.filters.StringFilter.java
  • Location: StringFilter.java
  • Purpose: Abstract base class for string-based filters in Nitrite.

Refactoring Changes in MigrationManager.java

1. Extract Method

• Description: Split doMigrate into closeDatabaseAndThrowException and executeMigrationPath methods.
• Details: closeDatabaseAndThrowException closes the database and throws an exception for invalid paths.
• Impact: executeMigrationPath handles the migration execution loop, reducing doMigrate’s complexity.
• Before: Error handling and execution were inline; now they’re separate methods.
• Location: Lines 66-76 and 84-95 in the refactored file.

2. Decompose Conditional

• Description: Separated nested if statements into blocks for migration need and path validation.
• Details: The migration check and path validity check are now distinct, sequential steps.
• Impact: Clarifies the control flow by isolating each decision point.
• Before: Nested conditionals mixed logic; now each block is focused.
• Location: Lines 54-64 in the refactored file.

3. Introduce Explaining Variable

• Description: Added migrationRequired, currentVersion, targetVersion, and hasValidPath variables.
• Details: migrationRequired flags the need; currentVersion and targetVersion rename versions.
• Impact: hasValidPath explains the path check, improving code comprehension.
• Before: Less descriptive names and inline checks; now variables clarify intent.
• Location: Lines 54, 56, 57, and 61 in the refactored file.

Refactoring Changes in StringFilter.java

1. Pull-up Method

• Description: Added toStringValue method to StringFilter to give it a specific role.
• Details: This method converts objects to strings safely, pulled up from potential subclass logic.
• Impact: Enhances the hierarchy by making StringFilter contribute behavior, not just structure.
• Before: StringFilter was an empty layer; now it has utility functionality.
• Location: Added around line 20 in the refactored file.

2. Extract Class

• Description: Created StringFilterHelper class to handle string utility logic.
• Details: Moved toStringValue to this new class, instantiated in StringFilter.
• Impact: Reduces StringFilter’s bloat, improving modularity and separation of concerns.
• Before: Logic was inline; now it’s delegated to a helper class.
• Location: New file StringFilterHelper.java and line 18 in StringFilter.java.

3. Replace Conditional with Polymorphism

• Description: Added abstract applyOnString method to enforce polymorphic behavior.
• Details: Subclasses like TextFilter implement this method, replacing potential type checks.
• Impact: Fixes "Broken Hierarchy" by defining a contract for string filters.
• Before: No specific behavior enforced; now subclasses must implement string matching.
• Location: Line 25 in the refactored file, implemented in subclasses.

Functionality Preservation

• MigrationManager.java:
  • Original: Checks migration need, finds a path, executes migrations, or throws an exception.
  • Refactored: Same behavior, reorganized for clarity.
  • Verification: Passes mvn clean install and mvn test.
• StringFilter.java:
  • Original: Base class with no behavior, extended by string filters.
  • Refactored: Adds utility and contract, behavior unchanged in subclasses.
  • Verification: Compiles and tests pass with updated subclasses (e.g., TextFilter).

Next Steps

• Documentation: Updated Javadoc for new methods/classes and README with refactoring details.
• Pull Request: Committed with messages:
  • "Refactor MigrationManager.doMigrate() with Extract Method, Decompose Conditional, and Introduce Explaining Variable"
  • "Refactor StringFilter to fix Broken Hierarchy with Pull-up Method, Extract Class, and Replace Conditional with Polymorphism"
  • Submitted to the original repository.

Summary by CodeRabbit

• New Features

  • Introduced a utility for safer object-to-text conversion, enhancing text filtering processes.
  • Enabled a customizable text-check capability for more flexible query matching.

• Refactor

  • Streamlined filtering logic to better manage special character handling.
  • Optimized update processes with improved error management during version transitions.

[coderabbitai]

Walkthrough

The changes enhance string filtering and migration logic. In the filters package, the StringFilter class now includes a private helper and a new utility method for string conversion, along with an abstract applyOnString method. A new StringFilterHelper class provides safe conversion of objects to strings. In TextFilter, the filtering logic is refactored to use a new applyOnString method that handles wildcard characters. The migration process in MigrationManager has been refactored by renaming version variables and extracting error handling and migration execution into dedicated private methods.

Changes

File(s)	Change Summary
nitrite/.../filters/StringFilter.java, nitrite/.../filters/StringFilterHelper.java, nitrite/.../filters/TextFilter.java	Added a new helper class (StringFilterHelper) with toStringValue(Object); introduced a private helper in StringFilter along with toStringValue(Object) and an abstract applyOnString(String); refactored TextFilter to include an applyOnString(String) method that encapsulates wildcard handling and streamlines filtering logic.
nitrite/.../migration/MigrationManager.java	Refactored the doMigrate method: renamed version variables to currentVersion and targetVersion, introduced a boolean check (hasValidPath), and extracted migration execution and error handling into new private methods (executeMigrationPath and closeDatabaseAndThrowException).

Sequence Diagram(s)

sequenceDiagram
    participant MM as MigrationManager
    participant DB as Database
    MM->>MM: Evaluate currentVersion & targetVersion
    MM->>MM: Check for valid migration path (hasValidPath)
    alt Valid migration path
        MM->>MM: executeMigrationPath(migrationSteps)
    else Invalid migration path
        MM->>DB: Close database
        MM->>MM: closeDatabaseAndThrowException() throws MigrationException
    end

Loading

Poem

Oh, what a hop, what a day so bright,
I’m a rabbit in code, leaping through byte-light.
New helpers and methods make the path so clear,
With filters refined, there’s nothing to fear!
Migration steps now dance in a well-ordered tune—
Hoppy changes rock, from sun up to moon!
🐇✨

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📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 2f8659f and d68f4e2.

📒 Files selected for processing (4)

• nitrite/src/main/java/org/dizitart/no2/filters/StringFilter.java (2 hunks)
• nitrite/src/main/java/org/dizitart/no2/filters/StringFilterHelper.java (1 hunks)
• nitrite/src/main/java/org/dizitart/no2/filters/TextFilter.java (2 hunks)
• nitrite/src/main/java/org/dizitart/no2/migration/MigrationManager.java (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (1)

• GitHub Check: Codacy Static Code Analysis

🔇 Additional comments (9)

nitrite/src/main/java/org/dizitart/no2/filters/StringFilterHelper.java (1)

1-7: Well-designed utility class for string conversion.

This new helper class follows the Single Responsibility Principle by focusing solely on safe string conversion. The implementation properly handles null values by returning an empty string instead of throwing NullPointerException.

nitrite/src/main/java/org/dizitart/no2/filters/StringFilter.java (3)

26-27: Good use of composition with the StringFilterHelper.

The field is correctly marked as final since it doesn't need to change after initialization.

---

47-54: Good encapsulation of string conversion logic.

This method properly delegates to the StringFilterHelper, which ensures consistent string conversion behavior across the codebase.

---

56-56: Strong design with abstract method enforcement.

Adding this abstract method is an excellent use of the Template Method pattern, enforcing a contract for subclasses to implement string-based filtering logic.

nitrite/src/main/java/org/dizitart/no2/filters/TextFilter.java (2)

51-58: Good implementation of the abstract method with clear logic.

The implementation correctly handles wildcard characters and performs case-insensitive string matching. This approach follows the DRY principle by extracting logic that was previously duplicated.

---

60-78: Well-documented and refactored method.

The Javadoc provides clear information about the method's purpose and behavior. The implementation has been simplified by delegating to the new applyOnString method, which reduces code duplication.

nitrite/src/main/java/org/dizitart/no2/migration/MigrationManager.java (3)

49-62: Improved readability with explaining variables and decomposed conditionals.

The refactoring makes the code more self-documenting by using descriptive variable names (currentVersion, targetVersion, hasValidPath) and extracting complex logic into separate methods.

---

64-73: Well-extracted error handling logic.

Extracting this error handling into a dedicated method follows the Single Responsibility Principle and makes the code more maintainable. The method handles database closure properly and provides a clear error message.

---

75-84: Effectively extracted migration execution logic.

The extraction of migration execution logic into a separate method improves code readability and maintainability. This follows the Extract Method refactoring pattern recommended for addressing the "Long Method" code smell.

✨ Finishing Touches

• 📝 Generate Docstrings

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