Improve Deno compatibility: config-first and safe env access (#3547)

* Set default PostgreSQL user to 'postgres' to avoid Deno env access errors

Currently, the pg package defaults the database user to process.env.USER (or USERNAME on Windows).  
This causes errors when running in Deno without --allow-env, as environment access is restricted.

This PR changes the default user to 'postgres', so:

- Node.js behavior is unchanged when a user is explicitly provided in config.
- Deno users no longer hit NotCapable errors for environment access.
- Avoids relying on process.env for default values.

Example:

Before:
user: process.platform === 'win32' ? process.env.USERNAME : process.env.USER,

After:
user: 'postgres', // default user, avoids using process.env

* Prioritize config values over environment variables in ConnectionParameters

Previously, ConnectionParameters would first check process.env for connection settings before using the provided config object. This could cause errors in environments like Deno where environment access is restricted.

This change updates the val function to:

1. Use the value from config if it is defined.


2. Fall back to environment variables only if config does not provide a value.


3. Use default values if neither config nor environment variables are set.



This ensures that explicitly provided configuration values are always respected, avoiding unnecessary errors in restricted environments.

* Wrap NODE_PG_FORCE_NATIVE check in try/catch for Deno compatibility

Replace the `typeof process.env.NODE_PG_FORCE_NATIVE !== 'undefined'` check with a try/catch
to safely handle environments like Deno without `--allow-env`.

- Keeps Node.js behavior unchanged.
- Prevents errors when accessing process.env in Deno.
- Preserves lazy loading of the native module.

* Make default database user Deno-safe

Wrap the default database user assignment in a try/catch to prevent errors when environment access is restricted (e.g., in Deno).

- Uses process.env.USER / USERNAME on Node if available
- Falls back to 'postgres' when env access fails or is unavailable
- Maintains code structure and comments
- Ensures Node tests continue to pass while preventing Deno runtime errors

* Fixing checks pass

* Update packages/pg/lib/connection-parameters.js

Co-authored-by: Charmander <~@charmander.me>

* fix(pg): only guard process.env access when forcing native client

---------

Co-authored-by: Charmander <~@charmander.me>

Author: Jobians

packages/pg/lib/connection-parameters.js

@@ -7,6 +7,10 @@ const defaults = require('./defaults')
 const parse = require('pg-connection-string').parse // parses a connection string
 
 const val = function (key, config, envVar) {
+  if (config[key]) {
+    return config[key]
+  }
+
   if (envVar === undefined) {
     envVar = process.env['PG' + key.toUpperCase()]
   } else if (envVar === false) {
@@ -15,7 +19,7 @@ const val = function (key, config, envVar) {
     envVar = process.env[envVar]
   }
 
-  return config[key] || envVar || defaults[key]
+  return envVar || defaults[key]
 }
 
 const readSSLConfigFromEnvironment = function () {

packages/pg/lib/defaults.js

@@ -1,11 +1,18 @@
 'use strict'
 
+let user
+try {
+  user = process.platform === 'win32' ? process.env.USERNAME : process.env.USER
+} catch {
+  // ignore, e.g., Deno without --allow-env
+}
+
 module.exports = {
   // database host. defaults to localhost
   host: 'localhost',
 
   // database user's name
-  user: process.platform === 'win32' ? process.env.USERNAME : process.env.USER,
+  user,
 
   // name of database to connect
   database: undefined,

packages/pg/lib/index.js

@@ -34,31 +34,40 @@ const PG = function (clientConstructor) {
   this.utils = utils
 }
 
-if (typeof process.env.NODE_PG_FORCE_NATIVE !== 'undefined') {
-  module.exports = new PG(require('./native'))
-} else {
-  module.exports = new PG(Client)
+let clientConstructor = Client
 
-  // lazy require native module...the native module may not have installed
-  Object.defineProperty(module.exports, 'native', {
-    configurable: true,
-    enumerable: false,
-    get() {
-      let native = null
-      try {
-        native = new PG(require('./native'))
-      } catch (err) {
-        if (err.code !== 'MODULE_NOT_FOUND') {
-          throw err
-        }
+let forceNative = false
+try {
+  forceNative = !!process.env.NODE_PG_FORCE_NATIVE
+} catch {
+  // ignore, e.g., Deno without --allow-env
+}
+
+if (forceNative) {
+  clientConstructor = require('./native')
+}
+
+module.exports = new PG(clientConstructor)
+
+// lazy require native module...the native module may not have installed
+Object.defineProperty(module.exports, 'native', {
+  configurable: true,
+  enumerable: false,
+  get() {
+    let native = null
+    try {
+      native = new PG(require('./native'))
+    } catch (err) {
+      if (err.code !== 'MODULE_NOT_FOUND') {
+        throw err
       }
+    }
 
-      // overwrite module.exports.native so that getter is never called again
-      Object.defineProperty(module.exports, 'native', {
-        value: native,
-      })
+    // overwrite module.exports.native so that getter is never called again
+    Object.defineProperty(module.exports, 'native', {
+      value: native,
+    })
 
-      return native
-    },
-  })
-}
+    return native
+  },
+})