Node postgres (pg) template string

util.ts

import type { CustomTypesConfig, QueryConfig } from 'pg';

export class Template_Query_Config implements QueryConfig {
	private name_?: string;
	private types_?: CustomTypesConfig;

	constructor(private readonly strings: string[], readonly values: any[]) {}

	get text(): string {
		return (
			this.strings
				// join strings to query text
				.reduce((prev, curr, i) => prev + '$' + i + curr)
				// remove whitespace
				.replace(/(?:\n\s*)/g, ' ')
		);
	}

	get name(): string | undefined {
		return this.name_;
	}

	get types(): CustomTypesConfig | undefined {
		return this.types_;
	}

	private merge(current: Template_Query_Config, statement: string | Template_Query_Config): void {
		if (statement instanceof Template_Query_Config) {
			current.strings[current.strings.length - 1] += statement.strings[0];
			current.strings.push(...statement.strings.slice(1));
			current.values.push(...statement.values);
		} else {
			current.strings[current.strings.length - 1] += statement;
		}
	}

	append(statement: string | Template_Query_Config): Template_Query_Config {
		if (!statement) return this;
		this.merge(this, statement);
		return this;
	}

	concat(statement: string | Template_Query_Config): Template_Query_Config {
		const clone = new Template_Query_Config([...this.strings], [...this.values]);
		this.merge(clone, statement);
		return clone.with_name(this.name_).with_types(this.types_);
	}

	with_name(name?: string): Template_Query_Config {
		this.name_ = name;
		return this;
	}

	with_types(types?: CustomTypesConfig): Template_Query_Config {
		this.types_ = types;
		return this;
	}
}

export function sql(query: TemplateStringsArray, ...values: any[]): Template_Query_Config {
	const strings = Array.from(query);
	return new Template_Query_Config(strings, values);
}

Usage:

const people_query = sql`select id, name, age from person where age < ${35} limit ${20}`;
await client.query(people_query);