diff --git a/README.md b/README.md
index 22a1f7dd..f3151d32 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 # validate
-[![version 1.0.0-beta](https://img.shields.io/badge/pub-v1.0.0--beta-red.svg)](https://pub.dartlang.org/packages/angel_validate)
+[![version 1.0.0](https://img.shields.io/badge/pub-v1.0.0-red.svg)](https://pub.dartlang.org/packages/angel_validate)
 [![build status](https://travis-ci.org/angel-dart/validate.svg)](https://travis-ci.org/angel-dart/validate)
 
 (Still missing several tests)
@@ -23,6 +23,7 @@ For convenience's sake, this library also exports `matcher`.
   * [Default Values](#default-values)
   * [Custom Validator Functions](#custom-validator-functions)
 * [Auto-parsing Numbers](#autoparse)
+* [Filtering Maps](#filter)
 * [Custom Error Messages](#custom-error-messages)
 * [Extending Validators](#extending-validators)
 * [Bundled Matchers](#bundled-matchers)
@@ -166,6 +167,16 @@ main() {
 
 You can also call `checkParsed` or `enforceParsed` as a shorthand.
 
+# filter
+This is a helper function to extract only the desired keys from a `Map`.
+
+```dart
+var inputData = {'foo': 'bar', 'a': 'b', '1': 2};
+var only = filter(inputData, ['foo']);
+
+print(only); // { foo: bar }
+```
+
 # Extending Validators
 You can add situation-specific rules within a child validator.
 You can also use `extend` to mark fields as required or forbidden that originally
@@ -257,12 +268,14 @@ main() {
 
 # Use with Angel
 
-`server.dart` exposes five helper middleware:
+`server.dart` exposes seven helper middleware:
 * `validate(validator)`: Validates and filters `req.body`, and throws an `AngelHttpException.BadRequest` if data is invalid.
 * `validateEvent(validator)`: Sets `e.data` to the result of validation on a service event.
 * `validateQuery(validator)`: Same as `validate`, but operates on `req.query`.
 * `autoParseBody(fields)`: Auto-parses numbers in `req.body`.
 * `autoParseQuery(fields)`: Same as `autoParseBody`, but operates on `req.query`.
+* `filterBody(only)`: Filters unwanted data out of `req.body`.
+* `filterQuery(only)`: Same as `filterBody`, but operates on `req.query`.
 
 ```dart
 import 'package:angel_framework/angel_framework.dart';
diff --git a/lib/server.dart b/lib/server.dart
index 397b4b12..fc5bf6ef 100644
--- a/lib/server.dart
+++ b/lib/server.dart
@@ -21,6 +21,28 @@ RequestMiddleware autoParseQuery(List<String> fields) {
   };
 }
 
+/// Filters unwanted data out of `req.body`.
+RequestMiddleware filterBody(Iterable<String> only) {
+  return (RequestContext req, res) async {
+    var filtered = filter(req.body, only);
+    req.body
+      ..clear()
+      ..addAll(filtered);
+    return true;
+  };
+}
+
+/// Filters unwanted data out of `req.query`.
+RequestMiddleware filterQuery(Iterable<String> only) {
+  return (RequestContext req, res) async {
+    var filtered = filter(req.query, only);
+    req.query
+      ..clear()
+      ..addAll(filtered);
+    return true;
+  };
+}
+
 /// Validates the data in `req.body`, and sets the body to
 /// filtered data before continuing the response.
 RequestMiddleware validate(Validator validator,
diff --git a/lib/src/validator.dart b/lib/src/validator.dart
index 13286ec2..12452425 100644
--- a/lib/src/validator.dart
+++ b/lib/src/validator.dart
@@ -14,7 +14,7 @@ typedef String CustomErrorMessageFunction(item);
 typedef bool Filter(value);
 
 /// Converts the desired fields to their numeric representations, if present.
-Map<String, dynamic> autoParse(Map inputData, List<String> fields) {
+Map<String, dynamic> autoParse(Map inputData, Iterable<String> fields) {
   Map<String, dynamic> data = {};
 
   for (var key in inputData.keys) {
@@ -33,6 +33,14 @@ Map<String, dynamic> autoParse(Map inputData, List<String> fields) {
   return data;
 }
 
+/// Removes undesired fields from a `Map`.
+Map<String, dynamic> filter(Map inputData, Iterable<String> only) {
+  return inputData.keys.fold(<String, dynamic>{}, (map, key) {
+    if (only.contains(key)) map[key] = inputData[key];
+    return map;
+  });
+}
+
 /// Enforces the validity of input data, according to [Matcher]s.
 class Validator extends Matcher {
   /// Pre-defined error messages for certain fields.
diff --git a/pubspec.yaml b/pubspec.yaml
index a4a323ee..f6555622 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: angel_validate
 description: Cross-platform validation library based on `matcher`.
-version: 1.0.0-beta
+version: 1.0.0
 author: Tobe O <thosakwe@gmail.com>
 homepage: https://github.com/angel-dart/validate
 environment:
diff --git a/test/basic_test.dart b/test/basic_test.dart
index 654497cc..3429af59 100644
--- a/test/basic_test.dart
+++ b/test/basic_test.dart
@@ -1,11 +1,8 @@
 import 'package:angel_validate/angel_validate.dart';
 import 'package:test/test.dart';
 
-final Validator emailSchema = new Validator({
-  'to': isEmail
-}, customErrorMessages: {
-  'to': 'Hello, world!'
-});
+final Validator emailSchema = new Validator({'to': isEmail},
+    customErrorMessages: {'to': 'Hello, world!'});
 
 final Validator todoSchema = new Validator({
   'id': [isInt, isPositive],
@@ -30,4 +27,10 @@ main() {
           .enforce({'id': 'fool', 'text': 'Hello, world!', 'completed': 4});
     }, throwsA(new isInstanceOf<ValidationException>()));
   });
+
+  test('filter', () {
+    var inputData = {'foo': 'bar', 'a': 'b', '1': 2};
+    var only = filter(inputData, ['foo']);
+    expect(only, equals({'foo': 'bar'}));
+  });
 }