Fast JSON parser for java projects.

The easiest way to get started is to look at maven-example. For more comprehensive examples, check out the unit tests or the demo.

For Java projects, to use this library, add this to your build.gradle file:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

...

dependencies {
  implementation 'com.github.instagram.ig-json-parser:runtime:master-SNAPSHOT' // the runtime
  implementation 'com.github.instagram.ig-json-parser:processor:master-SNAPSHOT' // the annotation processor
}

For Android projects using Android Studio 3.0+ or Gradle 4.0+, you can enable the annotation processor as following:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

...

dependencies {
  annotationProcessor 'com.github.instagram.ig-json-parser:processor:master-SNAPSHOT'
  implementation 'com.github.instagram.ig-json-parser:runtime:master-SNAPSHOT'
}

If you are using older gradle versions, you can use old apt plugin to integrate the annotation processor:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

...

apply plugin: 'com.neenbedankt.android-apt'

dependencies {
  apt 'com.github.instagram.ig-json-parser:processor:master-SNAPSHOT'
  implementation 'com.github.instagram.ig-json-parser:runtime:master-SNAPSHOT'
}

If you are using other build systems, please find instructions here

There should be a package-visible no-argument constructor for each of your model classes. The fields also need to be package-visible.

Each class that needs a serializer/deserializer generated should be annotated with @JsonType. Each field that needs to be mapped to/from JSON should be annotated with @JsonField. The @JsonField annotation has one mandatory argument, which is the fieldname for the field in the JSON.

The following is an example of a very simple model class:

@JsonType
class Dessert {
  @JsonField(fieldName="type")
  String type;

  @JsonField(fieldName="rating")
  float rating;
}

Compiling your model classes with the annotations will automatically generate the serializer and deserializer. They will be in a generated class with the same name as your class, except with the suffix __JsonHelper. For example, to deserialize the Dessert class above, simply run the code:

Dessert parsed = Dessert__JsonHelper.parseFromJson(inputJsonString);

To serialize a class, run:

String serialized = Dessert__JsonHelper.serializeToJson(dessertObject);

The following scalar types are supported:

• String
• boolean/Boolean
• int/Integer
• long/Long
• float/Float
• double/Double

The following collection types are supported:

• List/ArrayList
• Queue/ArrayDeque
• Map/HashMap
• Set/HashSet

If a json field is another dictionary, it can be represented by another model class. That model class must also have the @JsonType annotation.

Add the following lines to your proguard-rules file:

-dontwarn sun.misc.Unsafe
-dontwarn javax.annotation.**

If you need to process your JSON after a first pass, you can change your @JsonType annotation to be @JsonType(postprocess = true) and add a method to your code and add a method YourClass postprocess() which will be called after the JSON is processed (see: QuestionableDesignChoice in the example below)

  @JsonType
  public class Example {
    @JsonField(fieldName = "container")
    Container mContainer;

    @JsonType
    public static class Container {
        @JsonField(fieldName = "questionable_design_choice")
        List<QuestionableDesignChoice> mQuestionableDesignChoice;
    }

    @JsonType(postprocessingEnabled = true)
    public static class QuestionableDesignChoice {
        @JsonField(fieldName = "property")
        String mProperty;

        QuestionableDesignChoice postprocess() {
          // post-process things here...
          return this;
        }
    }
}

Parsing the supported data types is straightforward. For enums or built-in Java classes, you will need to add customized parsing.

Value extract formatters override how we extract the value from the JsonParser object, while serialize code formatters override how we serialize a java field back to json. We use the serde for PointF in the example below, where a point is represented as an array in json.

  @JsonField(
      fieldName = "position",
      valueExtractFormatter =
          "com.instagram.common.json.android.JsonTypeHelper.deserializePointF(${parser_object})",
      serializeCodeFormatter =
          "com.instagram.common.json.android.JsonTypeHelper.serializePointF("
              + "${generator_object}, \"${json_fieldname}\", ${object_varname}.${field_varname})")
  @Nullable
  protected PointF mPosition;

To save generating serializer code if you only need deserialization, serializer generation can be disabled or enabled globally and per-class. The default is to generate serializers for all classes. To disable generation globally, pass

-AgenerateSerializer=false

to the command-line arguments of javac. To override the default generation option for a single class, see JsonType.generateSerializer().

See the CONTRIBUTING file for how to help out. Contributions are always welcome!

ig-json-parser is MIT licensed, as found below or in the LICENSE file.

MIT License

Copyright (c) Facebook, Inc. and its affiliates.

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.

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