Add option to force use of Extended Queries (#3214)

This feature can be used as follows:

```
client.query({ text: 'SELECT 1', queryMode: 'extended' })
```

This will force the query to be sent with parse/bind/execute even when it has no parameters and disallows multiple statements being executed.  This can be useful in scenarios where you want to enforce more security & help prevent sql injection attacks...particularly by library authors.

---------

Co-authored-by: alxndrsn <alxndrsn>
Co-authored-by: Brian Carlson <brian.m.carlson@gmail.com>

docs/pages/apis/client.mdx

@@ -75,6 +75,9 @@ type QueryConfig {
 
   // custom type parsers just for this query result
   types?: Types;
+
+  // TODO: document
+  queryMode?: string;
 }
 ```
 

packages/pg-native/index.js

@@ -57,7 +57,7 @@ Client.prototype.query = function (text, values, cb) {
     cb = values
   }
 
-  if (Array.isArray(values) && values.length > 0) {
+  if (Array.isArray(values)) {
     queryFn = function () {
       return self.pq.sendQueryParams(text, values)
     }

packages/pg/lib/native/query.js

@@ -10,6 +10,7 @@ var NativeQuery = (module.exports = function (config, values, callback) {
   this.text = config.text
   this.values = config.values
   this.name = config.name
+  this.queryMode = config.queryMode
   this.callback = config.callback
   this.state = 'new'
   this._arrayMode = config.rowMode === 'array'
@@ -159,6 +160,8 @@ NativeQuery.prototype.submit = function (client) {
     }
     var vals = this.values.map(utils.prepareValue)
     client.native.query(this.text, vals, after)
+  } else if (this.queryMode === 'extended') {
+    client.native.query(this.text, [], after)
   } else {
     client.native.query(this.text, after)
   }

packages/pg/lib/query.js

@@ -16,6 +16,7 @@ class Query extends EventEmitter {
     this.rows = config.rows
     this.types = config.types
     this.name = config.name
+    this.queryMode = config.queryMode
     this.binary = config.binary
     // use unique portal name each time
     this.portal = config.portal || ''
@@ -32,6 +33,10 @@ class Query extends EventEmitter {
   }
 
   requiresPreparation() {
+    if (this.queryMode === 'extended') {
+      return true
+    }
+
     // named queries must always be prepared
     if (this.name) {
       return true

packages/pg/test/integration/client/multiple-results-tests.js

@@ -25,6 +25,31 @@ suite.test(
   })
 )
 
+suite.test(
+  'throws if queryMode set to "extended"',
+  co.wrap(function* () {
+    const client = new helper.Client()
+    yield client.connect()
+
+    // TODO should be text or sql?
+    try {
+      const results = yield client.query({
+        text: `SELECT 'foo'::text as name; SELECT 'bar'::text as baz`,
+        queryMode: 'extended',
+      })
+      assert.fail('Should have thrown')
+    } catch (err) {
+      if (err instanceof assert.AssertionError) throw err
+
+      assert.equal(err.severity, 'ERROR')
+      assert.equal(err.code, '42601')
+      assert.equal(err.message, 'cannot insert multiple commands into a prepared statement')
+    }
+
+    return client.end()
+  })
+)
+
 suite.test(
   'multiple selects work',
   co.wrap(function* () {