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https://github.com/cesarferreira/rxpaper

Reactive extension for NoSQL data storage on Android
https://github.com/cesarferreira/rxpaper

android kryo no-sql storage

Last synced: 24 days ago
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Reactive extension for NoSQL data storage on Android

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README 

        
# RxPaper

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



RxPaper is a [RxJava](https://github.com/ReactiveX/RxJava) wrapper for the cool [paper](https://github.com/pilgr/Paper) library, a [fast](#benchmark-results) NoSQL data storage for Android that lets you **save/restore** Java objects by using efficient [Kryo](https://github.com/EsotericSoftware/kryo) serialization and handling data structure changes automatically.



For the RxJava 2 version please go to [RxPaper2](https://github.com/pakoito/RxPaper2) made by [Pakoito](https://github.com/pakoito).



![Paper icon](https://raw.githubusercontent.com/pilgr/Paper/master/paper_icon.png)



### What's new for the new `PaperDB 2.0` (starting on `0.5.0`+ version)

* Update internal Kryo serializer to 4.0. The data format is changed, but Paper supports backward data compatibility automatically;

* Now 58% less methods count : [4037](http://www.methodscount.com/?lib=io.paperdb%3Apaperdb%3A2.0);

* Depends on data structure you may experience faster reading but slower writing.



#### Add dependency

```groovy

repositories {

    jcenter()

    maven { url "https://jitpack.io" }

 }

dependencies {

    compile 'com.cesarferreira.rxpaper:rxpaper:0.5.0'

}

```



#### Install



Init the library in your Application class



```java

public class SampleApplication extends Application {



    @Override

    public void onCreate() {

        super.onCreate();



        RxPaper.init(this);

    }

}



```



#### Save

Save data object. **Your custom classes must have no-arg constructor.**

Paper creates separate data file for each key.



```java

RxPaper.book()

        .write(key, value)

        .subscribe(success -> /* all good */ );



```

I'm serious: **Your custom classes must have no-arg constructor.**



#### Read

Read data objects. Paper instantiates exactly the classes which has been used in saved data. The limited backward and forward compatibility is supported. See [Handle data class changes](#handle-data-structure-changes).



Use default values if object doesn't exist in the storage.



```java



RxPaper.book()

        .read(key, defaultPersonValue)

        .subscribe(person -> /* all good */ );



```



#### Delete

Delete data for one key.



```java

RxPaper.book()

       .delete(key)

       .subscribe();

```



Completely destroys Paper storage.



```java

RxPaper.book()

       .destroy()

       .subscribe();

```



#### Exists

Check if a key is persisted



```java

RxPaper.book()

       .exists(key)

       .subscribe(success -> /* all good */);

```



#### Get all keys



Returns all keys for objects in the book.



```java

RxPaper.book()

       .getAllKeys()

       .subscribe(allKeys -> /* all good */);

```



#### Use custom book

You can create custom Book book separate storage using



```java

RxPaper.book("custom-book")...;

```



Any changes in one book doesn't affect to others books.



## Important information



Don't forget to specify which threads you want to use before subscribing to any data manipulation, or else it'll run on the UI thread.



```java

...

.subscribeOn(Schedulers.io())

.observeOn(AndroidSchedulers.mainThread())

.subscribe(...

 ```



#### Handle data structure changes

Class fields which has been removed will be ignored on restore and new fields will have their default values. For example, if you have following data class saved in Paper storage:



```java

class Person {

    public String firstName; // Cesar

    public String middleName; // Costa

}

```



And then you realized you need to change the class like:



```java

class Person {

    public String firstName; // Cesar

    // public String middleName; removed field, who cares about middle names

    public String lastName; // New field

}

```



Then on restore the _middleName_ field will be ignored and new _lastName_ field will have its default value _null_.



#### Exclude fields

Use _transient_ keyword for fields which you want to exclude from saving process.



```java

public transient String tempId = "default"; // Won't be saved

```

#### Proguard config

* Keep data classes:



```

-keep class my.package.data.model.** { *; }

```



alternatively you can implement _Serializable_ in all your data classes and keep all of them using:



```

-keep class * implements java.io.Serializable { *; }

```



* Keep library classes and its dependencies



```

-keep class io.paperdb.** { *; }

-keep class com.esotericsoftware.** { *; }

-dontwarn com.esotericsoftware.**

-keep class de.javakaffee.kryoserializers.** { *; }

-dontwarn de.javakaffee.kryoserializers.**

```



#### How it works

Paper is based on the following assumptions:

- Saved data on mobile are relatively small;

- Random file access on flash storage is very fast.



So each data object is saved in separate file and write/read operations write/read whole file.



The [Kryo](https://github.com/EsotericSoftware/kryo) is used for object graph serialization and to provide data compatibility support.



#### Benchmark results

Running [Benchmark](https://github.com/pilgr/Paper/blob/master/paperdb/src/androidTest/java/io/paperdb/benchmark/Benchmark.java) on Nexus 4, in ms:



| Benchmark                 | Paper    | [Hawk](https://github.com/orhanobut/hawk)

|---------------------------|----------|----------

| Read/write 500 contacts   | 187      | 447                |

| Write 500 contacts        | 108      | 221               |

| Read 500 contacts         | 79       | 155                |