feat: Add multihost support for native js driver

Author: maxbronnikov10

.gitignore

@@ -10,3 +10,4 @@ dist
 /.eslintcache
 .vscode/
 manually-test-on-heroku.js
+.history

packages/pg/lib/client.js

@@ -81,6 +81,9 @@ class Client extends EventEmitter {
         keepAlive: c.keepAlive || false,
         keepAliveInitialDelayMillis: c.keepAliveInitialDelayMillis || 0,
         encoding: this.connectionParameters.client_encoding || 'utf8',
+        targetSessionAttrs: c.targetSessionAttrs || this.connectionParameters.targetSessionAttrs || null,
+        trustParameterStatus: c.trustParameterStatus || false,
+        Promise: this._Promise,
       })
     this._queryQueue = []
     this.binary = c.binary || defaults.binary
@@ -155,7 +158,7 @@ class Client extends EventEmitter {
       }
     }
 
-    if (this.host && this.host.indexOf('/') === 0) {
+    if (!Array.isArray(this.host) && this.host && this.host.indexOf('/') === 0) {
       con.connect(this.host + '/.s.PGSQL.' + this.port)
     } else {
       con.connect(this.port, this.host)
@@ -542,7 +545,7 @@ class Client extends EventEmitter {
     if (client.activeQuery === query) {
       const con = this.connection
 
-      if (this.host && this.host.indexOf('/') === 0) {
+      if (!Array.isArray(this.host) && this.host && this.host.indexOf('/') === 0) {
         con.connect(this.host + '/.s.PGSQL.' + this.port)
       } else {
         con.connect(this.port, this.host)

packages/pg/lib/connection-parameters.js

@@ -67,9 +67,16 @@ class ConnectionParameters {
       this.database = this.user
     }
 
-    this.port = parseInt(val('port', config), 10)
+    const rawPort = val('port', config)
+    this.port = Array.isArray(rawPort) ? rawPort.map((p) => parseInt(p, 10)) : parseInt(rawPort, 10)
     this.host = val('host', config)
 
+    const hosts = Array.isArray(this.host) ? this.host : [this.host]
+    const ports = Array.isArray(this.port) ? this.port : [this.port]
+    if (ports.length !== 1 && ports.length !== hosts.length) {
+      throw new Error(`ports must have either 1 entry or the same number of entries as hosts (${hosts.length})`)
+    }
+
     // "hiding" the password so it doesn't show up in stack traces
     // or if the client is console.logged
     Object.defineProperty(this, 'password', {
@@ -111,6 +118,17 @@ class ConnectionParameters {
     this.idle_in_transaction_session_timeout = val('idle_in_transaction_session_timeout', config, false)
     this.query_timeout = val('query_timeout', config, false)
 
+    this.targetSessionAttrs = val('targetSessionAttrs', config)
+
+    const validTargetSessionAttrs = ['any', 'read-write', 'read-only', 'primary', 'standby', 'prefer-standby']
+    if (this.targetSessionAttrs && !validTargetSessionAttrs.includes(this.targetSessionAttrs)) {
+      throw new Error(
+        `invalid targetSessionAttrs value: "${this.targetSessionAttrs}". Must be one of: ${validTargetSessionAttrs.join(
+          ', '
+        )}`
+      )
+    }
+
     if (config.connectionTimeoutMillis === undefined) {
       this.connect_timeout = process.env.PGCONNECT_TIMEOUT || 0
     } else {