compare prepared statement text with previous to prevent incorrect queries (#1814)

* compare prepared statement text with previous to prevent incorrect queries - fixes #1813

* make suggested changes to error message

lib/client.js

@@ -276,7 +276,7 @@ Client.prototype._attachListeners = function (con) {
   // it again on the same client
   con.on('parseComplete', function (msg) {
     if (self.activeQuery.name) {
-      con.parsedStatements[self.activeQuery.name] = true
+      con.parsedStatements[self.activeQuery.name] = self.activeQuery.text
     }
   })
 

lib/native/query.js

@@ -139,12 +139,16 @@ NativeQuery.prototype.submit = function (client) {
     // check if the client has already executed this named query
     // if so...just execute it again - skip the planning phase
     if (client.namedQueries[this.name]) {
+      if (this.text && client.namedQueries[this.name] !== this.text) {
+        const err = new Error(`Prepared statements must be unique - '${this.name}' was used for a different statement`)
+        return after(err)
+      }
       return client.native.execute(this.name, values, after)
     }
     // plan the named query the first time, then execute it
     return client.native.prepare(this.name, this.text, values.length, function (err) {
       if (err) return after(err)
-      client.namedQueries[self.name] = true
+      client.namedQueries[self.name] = self.text
       return self.native.execute(self.name, values, after)
     })
   } else if (this.values) {

lib/query.js

@@ -148,6 +148,10 @@ Query.prototype.submit = function (connection) {
   if (typeof this.text !== 'string' && typeof this.name !== 'string') {
     return new Error('A query must have either text or a name. Supplying neither is unsupported.')
   }
+  const previous = connection.parsedStatements[this.name]
+  if (this.text && previous && this.text !== previous) {
+    return new Error(`Prepared statements must be unique - '${this.name}' was used for a different statement`)
+  }
   if (this.values && !Array.isArray(this.values)) {
     return new Error('Query values must be an array')
   }

test/integration/client/prepared-statement-tests.js

@@ -56,6 +56,17 @@ var suite = new helper.Suite()
 
     q.on('end', () => done())
   })
+
+  suite.test('with same name, but with different text', function (done) {
+    client.query(new Query({
+      text: 'select name from person where age >= $1 and name LIKE $2',
+      name: queryName,
+      values: [30, '%n%']
+    }), assert.calls(err => {
+      assert.equal(err.message, `Prepared statements must be unique - '${queryName}' was used for a different statement`)
+      done()
+    }))
+  })
 })()
 
 ;(function () {