adding support for db warnings.

lib/database.js

@@ -20,6 +20,19 @@ var $arr = require('./array');
  * Represents the database protocol, extensible via event {@link event:extend extend}.
  * This type is not available directly, it can only be created via the library's base call.
  *
+ * **IMPORTANT:**
+ *
+ * For any given connection, you should only create a single database object in a separate module,
+ * to be shared in your application. If instead you keep creating the database object dynamically,
+ * your application will suffer from loss in performance and memory leaks because of event handlers
+ * that each database object needs to set up.
+ *
+ * Starting with version 4.7.0, if you create more than one database object for the same connection,
+ * you will see the following warning in a development environment (`NODE_ENV` = `development`):
+ * `WARNING: Creating a duplicate database object for the same connection.`
+ *
+ * See also property `noWarnings` in {@link module:pg-promise Initialization Options}.
+ *
  * @param {String|Object} cn
  * Database connection details, which can be:
  *
@@ -60,19 +73,27 @@ var $arr = require('./array');
  * {@link event:extend extend}
  *
  * @example
+ * 'use strict';
+ *
  * // Loading and initializing the library:
  * var pgp = require('pg-promise')({
  *     // Initialization Options
  * });
  *
+ * // Preparing the connection details:
  * var cn = "postgres://username:password@host:port/database";
  *
  * // Creating a new database instance from the connection details:
  * var db = pgp(cn);
  *
+ * // Exporting the database object:
+ * module.exports = db;
  */
 function Database(cn, dc, config) {
 
+    checkForDuplicates(cn, config);
+    setErrorHandler(cn, dc, config);
+
     var $p = config.promise;
 
     /**
@@ -1174,6 +1195,33 @@ function Database(cn, dc, config) {
 
 }
 
+var dbObjects = {};
+
+function checkForDuplicates(cn, config) {
+    var cnKey = JSON.stringify(cn);
+    if (cnKey in dbObjects) {
+        if (!config.options.noWarnings) {
+            var msg = "WARNING: Creating a duplicate database object for the same connection.\n" +
+                new Error().stack.split('\n').slice(4, 9).join('\n') + '\n';
+            $npm.utils.printWarning(msg);
+        }
+    } else {
+        dbObjects[cnKey] = true;
+    }
+}
+
+function setErrorHandler(cn, dc, config) {
+    // this event only happens when the connection is lost physically,
+    // which cannot be tested automatically; removing from coverage:
+    // istanbul ignore next
+    config.pgp.pg.on('error', function (err) {
+        $npm.events.error(config.options, err, {
+            cn: $npm.utils.getSafeConnection(cn),
+            dc: dc
+        });
+    });
+}
+
 module.exports = function (config) {
     var npm = config.$npm;
     npm.connect = npm.connect || $npm.connect(config);

lib/events.js

@@ -491,9 +491,9 @@ var $events = {
 
         /* istanbul ignore if */
         if (!$npm.main.suppressErrors) {
-            console.error("Unexpected error in '" + event + "' event handler.");
+            $npm.utils.printError("Unexpected error in '" + event + "' event handler.");
             if (!$npm.utils.isNull(err)) {
-                console.error(err.stack || err.message || err);
+                $npm.utils.printError(err.stack || err.message || err);
             }
         }
     }

lib/index.js

@@ -68,6 +68,17 @@ var $npm = {
  *
  * This property can be set dynamically (before or after initialization).
  *
+ * @param {boolean} [options.noWarnings]
+ * **Added in v.4.7.0**
+ *
+ * Disables all diagnostic warnings in the library.
+ *
+ * If it is not set (missing or `undefined`), it will default to the following:
+ * - `true`, if `NODE_ENV` != `development`
+ * - `false`, if `NODE_ENV` = `development`
+ *
+ * This property can be set dynamically (before or after initialization).
+ *
  * @param {function} [options.connect]
  * Global event {@link event:connect connect} handler.
  *
@@ -178,6 +189,10 @@ function $main(options) {
         }
     }
 
+    if (!('noWarnings' in options) || options.noWarnings === undefined) {
+        options.noWarnings = process.env.NODE_ENV !== 'development';
+    }
+
     var Database = require('./database')(config);
 
     var inst = function (cn, dc) {

lib/utils/index.js

@@ -124,7 +124,19 @@ function isPathAbsolute(path) {
     return path.charAt(0) === '/';
 }
 
+function printWarning(message) {
+    console.log("\u001b[33m" + message + "\u001b[0m");
+}
+
+// errors are disabled on Travis CI, so excluding from coverage:
+// istanbul ignore next
+function printError(message) {
+    console.log("\u001b[31m" + message + "\u001b[0m");
+}
+
 var exp = {
+    printError: printError,
+    printWarning: printWarning,
     isPathAbsolute: isPathAbsolute,
     lock: lock,
     isText: isText,
@@ -146,4 +158,3 @@ exp.startDir = mainFile ? $path.dirname(mainFile) : process.cwd();
 Object.freeze(exp);
 
 module.exports = exp;
-

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pg-promise",
-  "version": "4.6.5",
+  "version": "4.7.0",
   "description": "Promises interface for PostgreSQL",
   "main": "lib/index.js",
   "scripts": {

test/db/header.js

@@ -33,11 +33,17 @@ function main(options, dc) {
             }
         }
     }
+
+    if (options && typeof options === 'object') {
+        options.noWarnings = true;
+    }
+
     var result = {
         pgpLib: pgpLib,
         pgp: pgpLib(options),
         cn: cn
     };
+    result.pgp.pg.setMaxListeners(100);
     result.db = result.pgp(cn, dc);
     return result;
 }

test/entrySpec.js

@@ -81,7 +81,7 @@ describe("Library entry function", function () {
         describe("without any options", function () {
             var result;
             beforeEach(function (done) {
-                var db = header().db;
+                var db = header({noWarnings: true}).db;
                 db.query("select * from users")
                     .then(function (data) {
                         result = data;

typescript/README.MD

@@ -1,6 +1,6 @@
 ### TypeScript for pg-promise
 
-Complete TypeScript ambient declarations for [pg-promise] version 4.6.5 or later.
+Complete TypeScript ambient declarations for [pg-promise] version 4.7.0 or later.
 
 #### Inclusion
 

typescript/pg-promise.d.ts

@@ -1,5 +1,5 @@
 ////////////////////////////////////////
-// Requires pg-promise v4.6.5 or later.
+// Requires pg-promise v4.7.0 or later.
 ////////////////////////////////////////
 
 /// <reference path='./pg-subset' />
@@ -605,10 +605,11 @@ declare module 'pg-promise' {
         }
 
     }
-
+    
     // Library's Initialization Options
     // API: http://vitaly-t.github.io/pg-promise/module-pg-promise.html
     interface IOptions<Ext> {
+        noWarnings?:boolean;
         pgFormatting?:boolean;
         pgNative?:boolean,
         promiseLib?:any;