If you miss an extension, please open an issue or pull request

Resources:

• Documentation
• Pub Package
• GitHub Repository

On this page you can find some of the extensions. Take a look at the docs to see all of them.

Getting started 🎉

Add the following to your pubspec.yaml:

dependencies:
  dartx: any

After you import the library, you can use the extensions.

import 'package:dartx/dartx.dart';

var slice = [1, 2, 3, 4, 5].slice(1, -2); // [2, 3, 4]

Iterable

.slice()

Returns elements at indices between start (inclusive) and end (inclusive).

var list = [0, 1, 2, 3, 4, 5];
var last = list.slice(-1); // [5]
var lastHalf = list.slice(3); // [3, 4, 5]
var allButFirstAndLast = list.slice(1, -2); // [1, 2, 3, 4]

.sortedBy() & .thenBy()

Sort lists by multiple properties.

var dogs = [
  Dog(name: "Tom", age: 3),
  Dog(name: "Charlie", age: 7),
  Dog(name: "Bark", age: 1),
  Dog(name: "Cookie", age: 4),
  Dog(name: "Charlie", age: 2),
];

var sorted = dogs
    .sortedBy((dog) => dog.name)
    .thenByDescending((dog) => dog.age);
// Bark, Cookie, Charlie (7), Charlie (2), Tom

.distinctBy()

Get distinct elements from a list.

var list = ['this', 'is', 'a', 'test'];
var distinctByLength = list.distinctBy((it) => it.length); // ['this', 'is', 'a']

.flatten()

Get a new lazy Iterable of all elements from all collections in a collection.

var nestedList = [[1, 2, 3], [4, 5, 6]];
var flattened = nestedList.flatten(); // [1, 2, 3, 4, 5, 6]

.chunkWhile() & .splitWhen()

Chunk entries as long as long as two elements match a predicate:

final list = [1, 2, 4, 9, 10, 11, 12, 15, 16, 19, 20, 21];
final increasingSubSequences = list.chunkWhile((a, b) => a + 1 == b);

// increasingSubSequences = [[1, 2], [4], [9], [10, 11, 12], [15, 16], [19, 20, 21]]

splitWhen is the opposite of chunkWhile that starts a new chunk every time the predicate didn't match.

String

.chars

Get a list of single character strings from a string. Supports emojis.

var chars = 'family👨‍👨‍👧‍👦'.chars; // ['f', 'a', 'm', 'i', 'l', 'y', '👨‍👨‍👧‍👦']

.isBlank

Returns true if this string is empty or consists solely of whitespace characters.

var notBlank = '   .'.isBlank; // false
var blank = '  '.isBlank; // true

.toIntOrNull()

Parses the string as an integer or returns null if it is not a number.

var number = '12345'.toIntOrNull(); // 12345
var notANumber = '123-45'.toIntOrNull(); // null

.removePrefix(), .removeSuffix() and .removeSurrounding()

Remove a prefix, a suffix, or both from a given string:

var name = 'James Bond'.removePrefix('James '); // Bond
var milliseconds = '100ms'.removeSuffix('ms'); // 100
var text = '<p>Some HTML</p>'
  .removeSurrounding(prefix: '<p>', suffix: '</p>'); // Some HTML

Time utils

Dartx exports @jogboms great ⏰ time.dart package so you can do the following:

int secondsInADay = 1.days.inSeconds;

Duration totalTime = [12.5.seconds, 101.milliseconds, 2.5.minutes].sum();

DateTime oneWeekLater = DateTime.now() + 1.week;

Check out ⏰ time.dart for more information and examples.

num

.coerceIn()

Ensures that this value lies in the specified range.

var numberInRange = 123.coerceIn(0, 1000); // 123
var numberOutOfRange = -123.coerceIn(0, 1000); // 0

.toBytes()

Converts this value to binary form.

range

rangeTo

Creates a range between two ints (upwards, downwards and with custom steps)

// upwards with default step size 1
for (var i in 1.rangeTo(5)) {
  print(i); // 1, 2, 3, 4, 5
}
// downwards with custom step
for (var i in 10.rangeTo(2).step(2)) {
  print(i); // 10, 8, 6, 4, 2
}

Function

.invoke() - DEPRECATED

Use call() instead. This is very useful for null checks.

var func = (String value) {
  print(value);
}

func?.call('hello world');

.partial(), .partial2() ...

Applies some of the required arguments to a function and returns a function which takes the remaining arguments.

void greet(String firstName, String lastName) {
  print('Hi $firstName $lastName!');
}

var greetStark = greet.partial('Stark');
greetStark('Sansa'); // Hi Sansa Stark!
greetStark('Tony'); // Hi Tony Stark!

File

.name

Get the name and extension of a file.

var file = File('some/path/testFile.dart');
print(file.name); // testFile.dart
print(file.nameWithoutExtension); // testFile

.appendText()

Append text to a file.

await File('someFile.json').appendText('{test: true}');

.isWithin()

Checks if a file is inside a directory.

var dir = Directory('some/path');
File('some/path/file.dart').isWithin(dir); // true

Directory

.file(String)

References a file within a Directory

Directory androidDir = Directory('flutter-app/android');
File manifestFile = androidDir.file("app/src/main/AndroidManifest.xml");

References a directory within a Directory

.directory(String)

Directory androidDir = Directory('flutter-app/android');
Directory mainSrc = androidDir.directory("app/src/main");

.contains(FileSystemEntity entity, {bool recursive = false})

Checks if a Directory contains a FileSystemEntity. This can be a File or a Directory.

Use the recursive argument to include the subdirectories.

final File someFile = File('someFile.txt');
final Directory someDir = Directory('some/dir');

final Directory parentDir = Directory('parent/dir');

parentDir.contains(someFile);
parentDir.contains(someDir);
parentDir.contains(someFile, recursive: true);
parentDir.contains(someDir, recursive: true);

This is the async method, which returns a Future<bool>.

.containsSync(FileSystemEntity entity, {bool recursive = false})

Same as .contains(FileSystemEntity entity, {bool recursive = false}) but synchronous. Returns a bool.

License

Copyright 2019 Simon Leier

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.