plpgsql-parse

Comment preserving PL/pgSQL parser. A wrapper around plpgsql-parser and plpgsql-deparser that preserves -- line comments inside PL/pgSQL function bodies through parse-deparse round trips.

Installation

npm install plpgsql-parse

Features

• Body Comment Preservation -- Retains -- line comments inside PL/pgSQL function bodies ($$...$$) through parse-deparse cycles
• Outer SQL Comment Preservation -- Preserves comments and whitespace outside function definitions via pgsql-parse
• Idempotent Round-Trips -- parse -> deparse -> parse -> deparse produces identical output
• Non-Invasive -- Does not modify plpgsql-parser, plpgsql-deparser, or any other upstream packages

How It Works

1. Uses pgsql-parse for outer SQL comment and whitespace preservation
2. For each PL/pgSQL function, scans the $$...$$ body to extract -- comments with line numbers
3. Associates each comment with the nearest following PL/pgSQL statement (anchor)
4. On deparse, re-injects comments by matching statement keywords against the deparsed output

API

Parse

import { parseSync, deparseSync, loadModule } from 'plpgsql-parse';

await loadModule();

const result = parseSync(`
-- Create a counter function
CREATE FUNCTION get_count() RETURNS int LANGUAGE plpgsql AS $$
BEGIN
  -- Count active users
  RETURN (SELECT count(*) FROM users WHERE active);
END;
$$;
`);

// result.enhanced contains outer SQL comments/whitespace
// result.functions contains body comments for each PL/pgSQL function
const sql = deparseSync(result);
// Output preserves both outer and body comments

Credits

Built on the excellent work of several contributors:

• Dan Lynch -- official maintainer since 2018 and architect of the current implementation
• Lukas Fittl for libpg_query -- the core PostgreSQL parser that powers this project

🛠 Built by the Constructive team — creators of modular Postgres tooling for secure, composable backends. If you like our work, contribute on GitHub.

Related

• pgpm: A Postgres Package Manager that brings modular development to PostgreSQL with reusable packages, deterministic migrations, recursive dependency resolution, and tag-aware versioning.
• pgsql-test: Instant, isolated PostgreSQL databases for each test with automatic transaction rollbacks, context switching, and clean seeding for fast, reliable database testing.
• pgsql-seed: PostgreSQL seeding utilities for CSV, JSON, SQL data loading, and pgpm deployment.
• pgsql-parser: The real PostgreSQL parser for Node.js, providing symmetric parsing and deparsing of SQL statements with actual PostgreSQL parser integration.
• pgsql-deparser: A streamlined tool designed for converting PostgreSQL ASTs back into SQL queries, focusing solely on deparser functionality to complement pgsql-parser.
• @pgsql/parser: Multi-version PostgreSQL parser with dynamic version selection at runtime, supporting PostgreSQL 15, 16, and 17 in a single package.
• @pgsql/types: Offers TypeScript type definitions for PostgreSQL AST nodes, facilitating type-safe construction, analysis, and manipulation of ASTs.
• @pgsql/enums: Provides TypeScript enum definitions for PostgreSQL constants, enabling type-safe usage of PostgreSQL enums and constants in your applications.
• @pgsql/utils: A comprehensive utility library for PostgreSQL, offering type-safe AST node creation and enum value conversions, simplifying the construction and manipulation of PostgreSQL ASTs.
• @pgsql/traverse: PostgreSQL AST traversal utilities for pgsql-parser, providing a visitor pattern for traversing PostgreSQL Abstract Syntax Tree nodes, similar to Babel's traverse functionality but specifically designed for PostgreSQL AST structures.
• pg-proto-parser: A TypeScript tool that parses PostgreSQL Protocol Buffers definitions to generate TypeScript interfaces, utility functions, and JSON mappings for enums.
• libpg-query: The real PostgreSQL parser exposed for Node.js, used primarily in pgsql-parser for parsing and deparsing SQL queries.

Disclaimer

AS DESCRIBED IN THE LICENSES, THE SOFTWARE IS PROVIDED "AS IS", AT YOUR OWN RISK, AND WITHOUT WARRANTIES OF ANY KIND.

No developer or entity involved in creating Software will be liable for any claims or damages whatsoever associated with your use, inability to use, or your interaction with other users of the Software code or Software CLI, including any direct, indirect, incidental, special, exemplary, punitive or consequential damages, or loss of profits, cryptocurrencies, tokens, or anything else of value.