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Custom providers

Since version 1.2.0 of Datafaker it's possible create your own provider of data.

A full example can be found in the source code.

Custom hardcoded provider

To create a custom provider of data, you'll need to do the following steps:

  • Create custom provider of data
  • Create your own custom faker which extends Faker and register custom provider

In code, this would look like the following:

Hardcoded provider

Create a custom provider of data:

public static class Insect extends AbstractProvider<BaseProviders> {  private static final WeightedRandomSelector selector = new WeightedRandomSelector(new Random());   private static final String[] INSECT_NAMES = { "Ant", "Beetle", "Butterfly", "Wasp" };  private static final List<Map<String, Object>> WEIGHTED_INSECTS = List.of(  Map.of("value", "Driver ant", "weight", 6.0),  Map.of("value", "Fire ant", "weight", 3.0),  Map.of("value", "Harvester ant", "weight", 1.0)  );   public Insect(BaseProviders faker) {  super(faker);  }   public String nextInsectName() {  return INSECT_NAMES[faker.random().nextInt(INSECT_NAMES.length)];  }   public String weightedInsectName() {  return selector.select(WEIGHTED_INSECTS);  } }

Register provider

Create your own custom faker, which extends Faker, and register the custom provider:

public static class MyCustomFaker extends Faker {  public Insect insect() {  return getProvider(Insect.class, Insect::new, this);  } }

Usage

To use the custom faker, you can do the following:

MyCustomFaker myFaker = new MyCustomFaker(); System.out.println(myFaker.insect().nextInsectName());

This will print something like the following:

Wasp

Usafe of weigted random selector is in the POC stage and is currently available only for custom hardcoded providers.

To use a random selector based on weights, you can do the following:

MyCustomFaker myFaker = new MyCustomFaker(); System.out.println(myFaker.insect().weightedInsectName());

This will return a random insect name but based on the provided weights 

Driver ant

Custom provider using Yaml file

In case you have a large set of data to load, it might be better to use a Yaml file.

To create a custom provider of data fom a file, you'll need to do the following steps:

  • Create a custom provider of data
  • Create your own custom faker which extends Faker and register custom provider

Yaml provider

First, create the custom provider which loads the data from a file:

public class InsectFromFile extends AbstractProvider<BaseProviders> {  private static final String KEY = "insectsfromfile";   public InsectFromFile(BaseProviders faker) {  super(faker);  faker.addPath(Locale.ENGLISH, Paths.get("src/test/ants.yml"));  faker.addPath(Locale.ENGLISH, Paths.get("src/test/bees.yml"));  }   public String ant() {  return resolve(KEY + ".ants");  }   public String bee() {  return resolve(KEY + ".bees");  } }

The ants.yml would look like the following:

en:  faker:  insectsfromfile:  ants: ['Driver ant', 'Fire ant', 'Harvester ant', 'Honey ant', 'Leafcutter ant', 'Sahara desert ant']

And if you want to use multiple YAML files, the bees.yml would look like this:

en:  faker:  insectsfromfile:  bees: ['Bumblebee', 'Euglossine bee', 'Honeybee', 'Carpenter bee', 'Leaf-cutter bee', 'Mining bee']

Register provider

Registering the provider would happen like this:

public static class MyCustomFaker extends Faker {  public InsectFromFile insectFromFile() {  return getProvider(InsectFromFile.class, InsectFromFile::new, this);  } }

Usage

To use the custom faker, you can do the following:

MyCustomFaker myFaker = new MyCustomFaker(); System.out.println(myFaker.insectFromFile().ant());

This will print something like the following:

Honey ant
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