don't mutate params when preparing statement (#992)

lib/query.js

@@ -146,11 +146,8 @@ Query.prototype.prepare = function(connection) {
     }, true);
   }
 
-  //TODO is there some better way to prepare values for the database?
   if(self.values) {
-    for(var i = 0, len = self.values.length; i < len; i++) {
-      self.values[i] = utils.prepareValue(self.values[i]);
-    }
+    self.values = self.values.map(utils.prepareValue);
   }
 
   //http://developer.postgresql.org/pgdocs/postgres/protocol-flow.html#PROTOCOL-FLOW-EXT-QUERY

test/integration/client/simple-query-tests.js

@@ -57,6 +57,31 @@ test("simple query interface using addRow", function() {
   });
 });
 
+test("prepared statements do not mutate params", function() {
+
+  var client = helper.client();
+
+  var params = [1]
+
+  var query = client.query("select name from person where $1 = 1 order by name", params);
+
+  assert.deepEqual(params, [1])
+
+  client.on('drain', client.end.bind(client));
+
+  query.on('row', function(row, result) {
+    assert.ok(result);
+    result.addRow(row);
+  });
+
+  query.on('end', function(result) {
+    assert.lengthIs(result.rows, 26, "result returned wrong number of rows");
+    assert.lengthIs(result.rows, result.rowCount);
+    assert.equal(result.rows[0].name, "Aaron");
+    assert.equal(result.rows[25].name, "Zanzabar");
+  });
+});
+
 test("multiple simple queries", function() {
   var client = helper.client();
   client.query({ text: "create temp table bang(id serial, name varchar(5));insert into bang(name) VALUES('boom');"})