Package org.instancio

Interface InstancioApi<T>

  • Type Parameters:
    T - type being created
    All Known Subinterfaces:
    InstancioOfClassApi<T>
    All Known Implementing Classes:
    ClassInstancioApiImpl, InstancioApiImpl

    public interface InstancioApi<T>
    Instancio API for generating instances of a class populated with random data.
    Since:
    1.0.1
    • Method Detail

      • create

        T create()
        Creates a new instance of a class and populates it with data.

        Example:

        
             Person person = Instancio.of(Person.class).create();
         

        The returned object will have all its fields populated with random data, including collection and array fields.

        Returns:
        a fully populated object
      • stream

        Stream<T> stream()
        Creates an infinite stream of distinct, fully populated objects.

        Example:

        
             List<Person> persons = Instancio.of(Person.class)
                 .stream()
                 .limit(5)
                 .collect(Collectors.toList());
         
        Returns:
        an infinite stream of distinct, populated objects
        Since:
        1.1.9
      • toModel

        Model<T> toModel()
        Creates a model containing all the information for populating a class.

        The model can be useful when class population needs to be customised and the customisations need to be re-used in different parts of the code.

        Example:

        
             Model<Person> personModel = Instancio.of(Person.class)
                     .supply(field("fullName"), () -> "Jane Doe")
                     .toModel();
        
             // Re-use the model to create instances of Person class
             // without duplicating the model's details
             Person person = Instancio.of(personModel).create();
         

        Since the internal data of the model is not part of the public API, the Model interface does not contain any methods.

        Returns:
        a model containing all the details
      • ignore

        InstancioApi<T> ignore​(TargetSelector selector)
        Specifies that a class or field should be ignored.

        Example:

        
             Person person = Instancio.of(Person.class)
                     .ignore(field("pets"))  // Person.pets field
                     .ignore(field(Address.class, "phoneNumbers")) // Address.phoneNumbers field
                     .ignore(allStrings())
                     .create();
         

        will create a fully populated person, but will ignore the address field and all string fields.

        Parameters:
        selector - for fields and/or classes this method should be applied to
        Returns:
        API builder reference
      • withNullable

        InstancioApi<T> withNullable​(TargetSelector selector)
        Specifies that a field or class is nullable. By default, Instancio assigns non-null values. If marked as nullable, Instancio will randomly assign either a null or non-null value to fields of this type.

        Example:

        
             Person person = Instancio.of(Person.class)
                     .withNullable(allStrings())
                     .withNullable(field(Address.class))
                     .create();
         
        Parameters:
        selector - for fields and/or classes this method should be applied to
        Returns:
        API builder reference
      • set

        <V> InstancioApi<T> set​(TargetSelector selector,
                                @Nullable
                                V value)
        Sets a value for a field or class.

        Example: if a Person has a List<PhoneNumber>, the following will set all generated phone numbers' country codes to "+1".

        
             Person person = Instancio.of(Person.class)
                     .supply(field(PhoneNumber.class, "phoneNumbers"), "+1")
                     .create();
         

        For supplying random values, see supply(TargetSelector, Generator).

        Type Parameters:
        V - type of the value
        Parameters:
        selector - for fields and/or classes this method should be applied to
        value - value to set
        Returns:
        API builder reference
        See Also:
        supply(TargetSelector, Supplier)
      • supply

        <V> InstancioApi<T> supply​(TargetSelector selector,
                                   Supplier<V> supplier)
        Supplies a non-random value for a field or class using a Supplier.

        Example:

        
             Person person = Instancio.of(Person.class)
                     .supply(all(LocalDateTime.class), () -> LocalDateTime.now()) // set all dates to current time
                     .supply(field("fullName"), () -> "Homer Simpson") // set Person.fullName
                     .supply(field(Address.class, "phoneNumbers"), () -> List.of( // set Address.phoneNumbers
                         new PhoneNumber("+1", "123-45-67"),
                         new PhoneNumber("+1", "345-67-89")))
                     .create();
         

        Note: Instancio will not modify the supplied instance in any way. If the PhoneNumber class has other fields, they will be ignored.

        For supplying random values, see supply(TargetSelector, Generator).

        Type Parameters:
        V - type of the value to generate
        Parameters:
        selector - for fields and/or classes this method should be applied to
        supplier - providing the value for given selector
        Returns:
        API builder reference
        See Also:
        supply(TargetSelector, Generator)
      • supply

        <V> InstancioApi<T> supply​(TargetSelector selector,
                                   Generator<V> generator)
        Supplies a randomised value for a field or class using a custom Generator.

        Example:

        
             Person person = Instancio.of(Person.class)
                     .supply(field(Address.class, "phoneNumbers"), random -> List.of(
                             // Generate phone numbers with a random country code, either US or Mexico
                             new PhoneNumber(random.from("+1", "+52"), "123-55-66"),
                             new PhoneNumber(random.from("+1", "+52"), "123-77-88")))
                     .create();
         

        Note: Instancio will not modify the supplied instance in any way. If the PhoneNumber class has other fields, they will be ignored.

        Type Parameters:
        V - type of the value to generate
        Parameters:
        selector - for fields and/or classes this method should be applied to
        generator - that will provide the values
        Returns:
        API builder reference
      • generate

        <V,​S extends GeneratorSpec<V>> InstancioApi<T> generate​(TargetSelector selector,
                                                                      Function<Generators,​S> gen)
        Generates a random value for a field or class using a built-in generator.

        Example:

        
             Person person = Instancio.of(Person.class)
                     .generate(field("age"), gen -> gen.ints().min(18).max(100))
                     .generate(field("name"), gen -> gen.string().min(5).allowEmpty())
                     .generate(field(Address.class, "phoneNumbers"), gen -> gen.collection().minSize(5))
                     .generate(field(Address.class, "city"), gen -> gen.oneOf("Burnaby", "Vancouver", "Richmond"))
                     .create();
         
        Type Parameters:
        V - type of the value to generate
        S - generator spec type
        Parameters:
        selector - for fields and/or classes this method should be applied to
        gen - provider of built-in generators
        Returns:
        API builder reference
      • onComplete

        <V> InstancioApi<T> onComplete​(TargetSelector selector,
                                       OnCompleteCallback<V> callback)
        A callback that gets invoked after an object has been fully populated.

        Example:

        
             // Sets countryCode field on all instances of Phone to the specified value
             Person person = Instancio.of(Person.class)
                     .onComplete(all(Phone.class), (Phone phone) -> phone.setCountryCode("+1"))
                     .create();
         
        Type Parameters:
        V - type of object handled by the callback
        Parameters:
        selector - for fields and/or classes this method should be applied to
        callback - to invoke after object has been populated
        Returns:
        API builder reference
        Since:
        1.0.4
      • subtype

        InstancioApi<T> subtype​(TargetSelector selector,
                                Class<?> subtype)
        Maps target field or class to the given subtype. This can be used in the following cases:
        1. to specify an implementation for interfaces or abstract classes
        2. to override default implementations used by Instancio
        Specify an implementation for an abstract type

        When Instancio encounters an interface or an abstract type it is not aware of (for example, that is not part of the JDK), it will not be able to instantiate it. This method can be used to specify an implementation to use in such cases. For example:

        
             WidgetContainer container = Instancio.of(WidgetContainer.class)
                     .subtype(all(AbstractWidget.class), ConcreteWidget.class)
                     .create();
         

        Override default implementations

        By default, Instancio uses certain defaults for collection classes, for example ArrayList for List. If an alternative implementation is required, this method allows to specify it:

        
             Person person = Instancio.of(Person.class)
                     .subtype(all(List.class), LinkedList.class)
                     .create();
         

        will use the LinkedList implementation for all Lists.

        Parameters:
        selector - for fields and/or classes this method should be applied to
        subtype - to map the selector to
        Returns:
        API builder reference
        Since:
        1.4.0
      • withSettings

        InstancioApi<T> withSettings​(Settings settings)
        Override default settings for generated values. Settings include collection sizes, string lengths, numeric ranges, etc.
        Parameters:
        settings - to use
        Returns:
        API builder reference
      • withSeed

        InstancioApi<T> withSeed​(int seed)
        Set the seed value for the random number generator. If seed is not specified, a random seed will be used. Specifying a seed is useful for reproducing test results. By specifying the seed value, the same random data will be generated again.

        Example:

        
             // Generates a different UUID each time
             UUID result = Instancio.of(UUID.class).create();
        
             // Generates the same UUID
             UUID result = Instancio.of(UUID.class)
                     .withSeed(1234)
                     .create();
         
        Parameters:
        seed - for the random number generator
        Returns:
        API builder reference