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https://github.com/shopify/livedata-ktx

Kotlin extension for LiveData, chaining like RxJava
https://github.com/shopify/livedata-ktx

android architecture-components kotlin livedata rxjava

Last synced: 1 day ago
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Kotlin extension for LiveData, chaining like RxJava

Host: GitHub
URL: https://github.com/shopify/livedata-ktx
Owner: Shopify
License: mit
Created: 2018-04-21T15:36:05.000Z (over 6 years ago)
Default Branch: master
Last Pushed: 2023-03-21T17:51:10.000Z (almost 2 years ago)
Last Synced: 2024-12-25T00:06:14.979Z (1 day ago)
Topics: android, architecture-components, kotlin, livedata, rxjava
Language: Kotlin
Homepage:
Size: 211 KB
Stars: 468
Watchers: 395
Forks: 28
Open Issues: 5
Metadata Files:
- Readme: README.1.x.md
- Changelog: CHANGES.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md

Awesome Lists containing this project

README

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[ ![Download](https://api.bintray.com/packages/shopify/shopify-android/livedata-ktx/images/download.svg) ](https://bintray.com/shopify/shopify-android/livedata-ktx/_latestVersion)

[![Build Status](https://travis-ci.org/Shopify/livedata-ktx.svg?branch=master)](https://travis-ci.org/Shopify/livedata-ktx)

# livedata-ktx

Kotlin extension for LiveData, chaining like RxJava

# Getting Started

To add LiveData KTX to your project, add the following to your app module's build.gradle:

```groovy

implementation "com.shopify:livedata-ktx:VERSION"

```

#### For `android.arch.lifecycle:livedata:1.x`, please use `com.shopify:livedata-ktx:1.x`

#### For `androidx.lifecycle:livedata:2.x`, please use `com.shopify:livedata-ktx:2.x`

*(Check https://github.com/Shopify/livedata-ktx/releases for more information)*

# Usage

### Chaining LiveData

```kotlin

val liveData: MutableLiveData = MutableLiveData()

liveData

  .distinct()

  .filter { it == false }

  .map { true }

  .nonNull()

  .observe(lifecycleOwner, { result ->

    // result is non-null and always true

  })

```

### Remove observer

Because the input observer goes through a wrapper before it observes to source LiveData. So that you can't simply remove it by just calling origin method `liveData.removeObserver`.

The new observe method returns `Removable` interface that allows you to remove observer effectively.

```kotlin

val liveData: MutableLiveData = MutableLiveData()

val removable = liveData

  .nonNull()

  .observe(lifecycleOwner, {

    // TODO

  })

removable.removeObserver()

```

### SingleLiveData

It is a lifecycle-aware observable that sends only new updates after subscription, used for events like navigation and Snackbar messages. `livedata-ktx` has different implementation comparing to SingleLiveEvent from [google samples android-architecture](https://github.com/googlesamples/android-architecture/blob/dev-todo-mvvm-live/todoapp/app/src/main/java/com/example/android/architecture/blueprints/todoapp/SingleLiveEvent.java).

```kotlin

val liveData: MutableLiveData = SingleLiveData()

val actuals: MutableList = mutableListOf()

val observer: (t: Int?) -> Unit = { actuals.add(it) }

liveData.value = 1

liveData.observe(this, observer)

liveData.value = 2

liveData.value = 3

val expecteds = mutableListOf(2, 3)

assertEquals(expecteds, actuals)

```

For more use cases, please see the tests at [LiveDataTest.kt](https://github.com/shopify/livedata-ktx/blob/master/livedata-ktx/src/test/java/com/shopify/livedataktx/LiveDataTest.kt)

# Feel missing methods

Please suggest what you need by creating issues. I will support it as fast as I can.

# Contributing

Any contributions are welcome!  

Please check the [CONTRIBUTING](CONTRIBUTING.md) guideline before submitting a new issue. Wanna send PR? [Click HERE](https://github.com/shopify/livedata-ktx/pulls)

# Maintainers

- Francisco Cavedon <[@fcavedon](https://github.com/fcavedon)>

- Henry Tao <[@henrytao-me](https://github.com/henrytao-me)>

- Ivan Savytskyi <[@sav007](https://github.com/sav007)>

- Kris Orr <[@krisorr](https://github.com/krisorr)>

# License

    The MIT License (MIT)

    Copyright (c) 2018 Shopify Inc.

    Permission is hereby granted, free of charge, to any person obtaining a copy

    of this software and associated documentation files (the "Software"), to deal

    in the Software without restriction, including without limitation the rights

    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

    copies of the Software, and to permit persons to whom the Software is

    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in

    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

    THE SOFTWARE.