Deprecate query.on & query.once

Author: brianc

lib/client.js

@@ -362,6 +362,8 @@ Client.prototype.copyTo = function (text) {
   throw new Error("For PostgreSQL COPY TO/COPY FROM support npm install pg-copy-streams");
 };
 
+const DeprecatedQuery = require('./utils').deprecateEventEmitter(Query)
+
 Client.prototype.query = function (config, values, callback) {
   //can take in strings, config object or query object
   var query;
@@ -373,7 +375,7 @@ Client.prototype.query = function (config, values, callback) {
       query.callback = query.callback || values
     }
   } else {
-    query = new Query(config, values, callback)
+    query = new DeprecatedQuery(config, values, callback)
     result = query
   }
 

lib/native/client.js

@@ -109,6 +109,8 @@ Client.prototype.connect = function(cb) {
   return result
 };
 
+const DeprecatedQuery = require('../utils').deprecateEventEmitter(NativeQuery)
+
 //send a query to the server
 //this method is highly overloaded to take
 //1) string query, optional array of parameters, optional function callback
@@ -130,7 +132,7 @@ Client.prototype.query = function(config, values, callback) {
     return config;
   }
 
-  var query = new NativeQuery(config, values, callback);
+  var query = new DeprecatedQuery(config, values, callback);
   this._queryQueue.push(query);
   this._pulseQueryQueue();
   return query;

lib/native/query.js

@@ -78,8 +78,8 @@ NativeQuery.prototype.catch = function(callback) {
 NativeQuery.prototype._getPromise = function() {
   if (this._promise) return this._promise;
   this._promise = new Promise(function(resolve, reject) {
-    this.once('end', resolve);
-    this.once('error', reject);
+    this._once('end', resolve);
+    this._once('error', reject);
   }.bind(this));
   return this._promise;
 };

lib/query.js

@@ -64,8 +64,8 @@ Query.prototype.catch = function(callback) {
 Query.prototype._getPromise = function() {
   if (this._promise) return this._promise;
   this._promise = new Promise(function(resolve, reject) {
-    this.once('end', resolve);
-    this.once('error', reject);
+    this._once('end', resolve);
+    this._once('error', reject);
   }.bind(this));
   return this._promise;
 };

lib/utils.js

@@ -6,6 +6,7 @@
  * README.md file in the root directory of this source tree.
  */
 
+const util = require('util')
 var defaults = require('./defaults');
 
 function escapeElement(elementRepresentation) {
@@ -137,11 +138,29 @@ function normalizeQueryConfig (config, values, callback) {
   return config;
 }
 
+const queryEventEmitterOverloadDeprecationMessage = `
+Using the automatically created return value from client.query as an event emitter is deprecated.
+Use either the callback or promise interface.
+`
+
+const deprecateEventEmitter = function(Emitter) {
+  const Result = function () {
+    Emitter.apply(this, arguments)
+  }
+  util.inherits(Result, Emitter)
+  Result.prototype._on = Result.prototype.on
+  Result.prototype._once = Result.prototype.once
+  Result.prototype.on = util.deprecate(Result.prototype.on, queryEventEmitterOverloadDeprecationMessage)
+  Result.prototype.once = util.deprecate(Result.prototype.once, queryEventEmitterOverloadDeprecationMessage)
+  return Result
+}
+
 module.exports = {
   prepareValue: function prepareValueWrapper (value) {
     //this ensures that extra arguments do not get passed into prepareValue
     //by accident, eg: from calling values.map(utils.prepareValue)
     return prepareValue(value);
   },
-  normalizeQueryConfig: normalizeQueryConfig
+  normalizeQueryConfig: normalizeQueryConfig,
+  deprecateEventEmitter: deprecateEventEmitter,
 };