# Class: SelectableColumnCollector

Defined in: packages/core/src/transformers/SelectableColumnCollector.ts:76

A visitor that collects all ColumnReference instances from SQL query structures. This visitor scans through all clauses and collects all unique ColumnReference objects. It supports both regular column collection and upstream column collection for maximum search conditions in DynamicQuery scenarios.

Supported query types:

• SimpleSelectQuery: Basic SELECT queries with all standard clauses
• BinarySelectQuery: UNION, INTERSECT, EXCEPT queries (collects from both sides)
• Common Table Expressions (CTEs) within queries
• Subqueries and nested queries

Behavioral notes:

• Collects column references to tables defined in the root FROM/JOIN clauses
• For aliased columns (e.g., 'title as name'), collects both the original column reference ('title') AND the alias ('name') to enable complete dependency tracking
• When upstream option is enabled, collects all available columns from upstream sources (CTEs, subqueries, and tables) for maximum search conditions in DynamicQuery
• Automatically removes duplicates based on the specified duplicate detection mode

Use cases:

• Dependency analysis and schema migration tools
• Column usage tracking across complex queries including unions and CTEs
• Security analysis for column-level access control
• DynamicQuery maximum search condition column discovery

Example

// Basic usage - collect only referenced columns
const collector = new SelectableColumnCollector();
const columns = collector.collect(query);

// With upstream collection for DynamicQuery
const upstreamCollector = new SelectableColumnCollector(
  null, false, DuplicateDetectionMode.ColumnNameOnly, 
  { upstream: true }
);
const allColumns = upstreamCollector.collect(query);

// Works with union queries and CTEs
const unionQuery = SelectQueryParser.parse(`
  SELECT name, email FROM users 
  UNION 
  SELECT name, email FROM customers
`);
const unionColumns = collector.collect(unionQuery);

Related tests: packages/core/tests/transformers/SelectableColumnCollector.test.ts

Implements

• SqlComponentVisitor<void&gt;

Constructors

Constructor

new SelectableColumnCollector(tableColumnResolver?, includeWildCard?, duplicateDetection?, options?): SelectableColumnCollector

Defined in: packages/core/src/transformers/SelectableColumnCollector.ts:99

Creates a new instance of SelectableColumnCollector.

Parameters

tableColumnResolver?

The resolver used to resolve column references to their respective tables.

null | TableColumnResolver

includeWildCard?

boolean = false

If true, wildcard columns (e.g., *) are included in the collection.

duplicateDetection?

DuplicateDetectionMode = DuplicateDetectionMode.ColumnNameOnly

Specifies the duplicate detection mode: 'columnNameOnly' (default, only column name is used), or 'fullName' (table name + column name).

options?

Additional options for the collector.

ignoreCaseAndUnderscore?

boolean

If true, column names are compared without considering case and underscores.

upstream?

boolean

If true, collect all columns available from upstream sources for maximum search conditions in DynamicQuery.

Returns

SelectableColumnCollector

Methods

getValues()

getValues(): object[]

Defined in: packages/core/src/transformers/SelectableColumnCollector.ts:185

Returns

object[]

---

collect()

collect(arg): object[]

Defined in: packages/core/src/transformers/SelectableColumnCollector.ts:189

Parameters

arg

SqlComponent

Returns

object[]

---

visit()

visit(arg): void

Defined in: packages/core/src/transformers/SelectableColumnCollector.ts:262

Main entry point for the visitor pattern. Implements the shallow visit pattern to distinguish between root and recursive visits.

Parameters

arg

SqlComponent

Returns

void

Implementation of

SqlComponentVisitor.visit