Dsn Parser – Nextra

DSN & JDBC string parser with query params support in a light and modern package.

Features

👉 Parse individual fields (ie: driver, user, password, host...)
🖖 Handle query string parameters and converts to boolean and numeric values.
🦄 Handle special characters like /, :... in the password (some libs won't).
🚀 Error with indicative message / reasons (discriminated union or throwable).
🛡️ Don't leak passwords in the error message.
🙏 Assertion and typeguard helpers
🤗 Ecosystem friendly (ie: zod integration).

Install

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yarn add @httpx/dsn-parser

Usage

parseDsnOrThrow

Usage with exceptions

import { parseDsnOrThrow } from "@httpx/dsn-parser";
 
const dsn = "redis://user:p@/ssword@localhost:6379/0?ssl=true";
 
try {
  const parsedDsn = parseDsnOrThrow(dsn);
  assert.deepEqual(parsedDsn, {
    driver: "redis",
    pass: "p@/ssword",
    host: "localhost",
    user: "user",
    port: 6379,
    db: "0",
    params: {
      ssl: true,
    },
  });
} catch (e) {
  // example:
  // e -> Error("Can't parse dsn: Invalid port: 12345678 (INVALID_PORT)")
}

parseDsn

Usage with discriminated union.

import { parseDsn } from "@httpx/dsn-parser";
 
const dsn = "redis://user:p@/ssword@localhost:6379/0?ssl=true";
 
const parsed = parseDsn(dsn);
 
if (parsed.success) {
  assert.deepEqual(parsed.value, {
    driver: "redis",
    pass: "p@/ssword",
    host: "localhost",
    user: "user",
    port: 6379,
    db: "0",
    params: {
      ssl: true,
    },
  });
} else {
  assert.deepEqual(parsed, {
    success: false,
    // Reasons might vary
    reason: "INVALID_PORT",
    message: "Invalid http port: 12345678",
  });
}

Options

import { parseDsn, type ParseDsnOptions } from "@httpx/dsn-parser";
 
const dsn = "mySql://localhost:6379/db";
const parsed = parseDsn(dsn, {
  lowercaseDriver: true,
  // Overrides, allows to force some values (ParseDsnOptions)
  overrides: {
    db: "db3",
    port: undefined,
  },
});
 
assert.deepEqual(parsed.value, {
  driver: "mysql",
  host: "localhost",
  db: "db3",
});

Params	Type	Description
`lowercaseDriver`	`boolean`	Driver name in lowercase, default `false`
`overrides`	`ParseDsnOptions`	Overrides allows to force specific values

Utilities

Typeguard

import { isParsableDsn, type ParsableDsn } from "@httpx/dsn-parser";
 
const dsn = "postgresql://localhost:6379/db";
 
if (isParsableDsn(dsn)) {
  // known to be ParsableDSN
}

Assertion

import { assertParsableDsn, ParsableDsn } from "@httpx/dsn-parser";
 
try {
  assertParsableDsn("redis:/");
  // Type is narrowed to string (ParsableDsn) if it
  // didn't throw.
} catch (e) {
  assert.equal(e.message, "Cannot parse DSN (PARSE_ERROR)");
}

ParsableDsn

ParsableDsn is a weak opaque type.

declare const tag: unique symbol;
export type WeakOpaqueContainer<Token> = {
  readonly [tag]: Token;
};
export type ParsableDsn = string & WeakOpaqueContainer<'ParsableDsn'>;

It can be used to enforce that the isParsableDsn or assertParsableDsn have been used before usage.

import type { ParsableDsn } from "./dsn-parser.type";
import { assertParsableDsn } from "./assert-parsable-dsn";
 
// to opt-in, just change the dsn param type to `ParsableDsn` instead of `string`
const fnWithWeakOpaqueType = (dsn: ParsableDsn) => {
    // by explictly requiring a ParsableDsn, we can rely on typescript
    // to be sure that a validation has occured before (isParsableDsn or assertParsableDsn)
}
 
fnWithWeakOpaqueType('redis://localhost');  // ❌ typescript will complain
 
const dsn = 'redis://localhost';
assertParsableDsn(dsn);
fnWithWeakOpaqueType(dsn);  // ✅ working cause it was checked before

PS: WeakOpaque usage is totally optional, a nice to have if applicable

convertJdbcToDsn

Utility to convert jdbc (opens in a new tab) dsn. Useful for prisma using sqlserver (opens in a new tab).

import { convertJdbcToDsn } from "@httpx/dsn-parser";
 
const jdbcDsn =
  "sqlserver://localhost:1433;database=my-db;authentication=default;user=sa;password=pass03$;encrypt=true;trustServerCertificate=true";
 
const dsn = convertJdbcToDsn(jdbc);
 
// -> 'sqlserver://localhost:1433?database=my-db&authentication=default&user=sa&password=pass03$&encrypt=true&trustServerCertificate=true'

DSN parsing

Requirements

The minimum requirement for dsn parsing is to have a host and a driver (/[a-z0-9]+/i) defined. All other options are optional.

export type ParsedDsn = {
  driver: string;
  host: string;
  user?: string;
  pass?: string;
  port?: number;
  db?: string;
  /** Query params */
  params?: Record<string, number | string | boolean>;
};

DSN support

Things like:

const validExamples = [
  "postgresql://postgres:@localhost:5432/prisma-db",
  "redis://us_er-name:P@ass-_:?/ssw/rd@www.example.com:6379/0?cache=true",
  //...
];

should work.

Query parameters

Simple query parameters are supported (no arrays, no nested). For convenience it will cast 'true' and 'false' to booleans, parse numeric string to numbers if possible. When a query parameter does not contain a value, it will be returned as true.

const dsn = "redis://host?index=1&compress=false&ssl";
const parsed = parseDsn(dsn);
assert.deepEqual(parsed.value.params, {
  index: 1,
  compress: false,
  ssl: true,
});

Portability

parseDsn won't make any assumptions on default values (i.e: default port for mysql...).

Validation

parseDsn wraps its result in a discriminated union (opens in a new tab) to allow the retrieval of validation errors. No try... catchneeded and full typescript support.

Reason codes are guaranteed in semantic versions and messages does not leak credentials

const parsed = parseDsn("redis://localhost:65636");
assert.deepEqual(parsed, {
  success: false,
  reason: "INVALID_PORT",
  message: "Invalid port: 65636",
});
if (!parsed.success) {
  // `success: false` narrows the type to
  // {
  //   reason: 'PARSE_ERROR'|'INVALID_ARGUMENT'|...
  //   message: string
  // }
  log(parsed.reason);
}

Reason	Message	Comment
`'PARSE_ERROR'`	`Cannot parse DSN`	Regexp failed
`'INVALID_ARGUMENT'`	`DSN must be a string`
`'EMPTY_DSN'`	`DSN cannot be empty`
`'INVALID_PORT'`	`Invalid port: ${port}`	[1-65535]

Ecosystem

Zod integration example

The isParsableDsn can be easily plugged into zod custom validation. Example:

import { z } from "zod";
import { isParsableDsn, type ParsableDsn } from "@httpx/dsn-parser";
 
export const serverEnvSchema = z.object({
  PRISMA_DATABASE_URL: z.custom<ParsableDsn>(
    (dsn) => isParsableDsn(dsn),
    "Invalid DSN format."
  ),
});
 
serverEnvSchema.parse(process.env);

Faq

Why '/' in password matters

Some libs (ioredis...) still might fail parsing a password containing '/', unfortunately they're pretty convenient, i.e:

openssl rand 60 | openssl base64 -A
 
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