Interface InstancioApi<T>
- Type Parameters:
T
- type to create
- All Known Subinterfaces:
InstancioOfClassApi<T>
,InstancioOfCollectionApi<C>
- All Known Implementing Classes:
ApiImpl
,OfClassApiImpl
,OfCollectionApiImpl
,OfMapApiImpl
- Since:
- 1.0.1
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Method Summary
Modifier and TypeMethodDescriptionasResult()
Returns aResult
containing the created object and seed value used to generate its values.create()
Creates a new instance of a class and populates it with data.<V> InstancioApi<T>
generate
(TargetSelector selector, GeneratorSpec<V> spec) Customises values using arbitrary generator specs.<V> InstancioApi<T>
generate
(TargetSelector selector, GeneratorSpecProvider<V> gen) Customises values using built-in generators provided by thegen
parameter, of typeGenerators
.ignore
(TargetSelector selector) Specifies that a class or field should be ignored.lenient()
Disables strict mode in which unused selectors trigger an error.<V> InstancioApi<T>
onComplete
(TargetSelector selector, OnCompleteCallback<V> callback) A callback that gets invoked after an object has been fully populated.<V> InstancioApi<T>
set
(TargetSelector selector, V value) Sets a value to matching selector targets.stream()
Creates an infinite stream of distinct, fully populated objects.subtype
(TargetSelector selector, Class<?> subtype) Maps target field or class to the given subtype.<V> InstancioApi<T>
supply
(TargetSelector selector, Supplier<V> supplier) Supplies an object using aSupplier
.<V> InstancioApi<T>
supply
(TargetSelector selector, Generator<V> generator) Supplies an object using aGenerator
to matching selector targets.toModel()
Creates a model containing all the information for populating a class.withNullable
(TargetSelector selector) Specifies that a field or class is nullable.withSeed
(long seed) Sets the seed value for the random number generator.withSettings
(Settings settings) Override defaultSettings
for generating values.
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Method Details
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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
- Since:
- 1.0.1
-
asResult
Returns aResult
containing the created object and seed value used to generate its values. The seed value can be used to reproduce the same object again.- Returns:
- result containing the created object
- Since:
- 1.5.1
-
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
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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> simpsons = Instancio.of(Person.class) .set(field(Person::getLastName), "Simpson") .set(field(Address::getCity), "Springfield") .generate(field(Person::getAge), gen -> gen.ints().range(40, 50)) .toModel(); Person homer = Instancio.of(simpsons) .set(field(Person::getFirstName), "Homer") .set(all(Gender.class), Gender.MALE) .create(); Person marge = Instancio.of(simpsons) .set(field(Person::getFirstName), "Marge") .set(all(Gender.class), Gender.FEMALE) .create();
- Returns:
- a model that can be used as a template for creating objects
- Since:
- 1.0.1
-
ignore
Specifies that a class or field should be ignored.Example:
Person person = Instancio.of(Person.class) .ignore(field(Phone::getPhoneNumber)) .ignore(allStrings()) .create();
will create a fully populated person, but will ignore the
getPhoneNumber
field, and all strings.Precedence
This method has higher precedence than other API methods. Once a target is ignored, no other selectors will apply. For example, the following snippet will trigger an unused selector error because
field(Phone::getNumber)
is redundant:Person person = Instancio.of(Person.class) .ignore(all(Phone.class)) .set(field(Phone::getNumber), "123-45-56") .create();
Usage with Java records
If
ignore()
targets one of the required arguments of a record constructor, then a default value for the ignored type will be generated.Example:
record PersonRecord(String name, int age) {} PersonRecord person = Instancio.of(PersonRecord.class) .ignore(allInts()) .ignore(allStrings()) .create(); // will produce: PersonRecord[name=null, age=0]
- Parameters:
selector
- for fields and/or classes this method should be applied to- Returns:
- API builder reference
-
withNullable
Specifies that a field or class is nullable. By default, Instancio assigns non-null values to fields. If marked as nullable, Instancio will generate either a null or non-null value.Example:
Note: a type marked as nullable using this method is only nullable when declared as a field, but not as a collection element, or map key/value. For example,Person person = Instancio.of(Person.class) .withNullable(allStrings()) .withNullable(field(Person::getAddress)) .withNullable(fields().named("lastModified")) .create();
withNullable(allStrings())
will not generate nulls in aList<String>
.- Parameters:
selector
- for fields and/or classes this method should be applied to- Returns:
- API builder reference
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set
Sets a value to matching selector targets.Example: if
Person
class contains aList<Phone>
, the following snippet will set all the country code of all phone instances to "+1".Person person = Instancio.of(Person.class) .set(field(Phone::getCountryCode), "+1") .create();
- Type Parameters:
V
- type of the value- Parameters:
selector
- for fields and/or classes this method should be applied tovalue
- value to set- Returns:
- API builder reference
- See Also:
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supply
Supplies an object using aSupplier
.Example:
Person person = Instancio.of(Person.class) .supply(all(LocalDateTime.class), () -> LocalDateTime.now()) .supply(field(Address::getPhoneNumbers), () -> List.of( new PhoneNumber("+1", "123-45-67"), new PhoneNumber("+1", "345-67-89"))) .create();
Note: Instancio will not
- populate or modify objects supplied by this method
- apply other
set()
,supply()
, orgenerate()
} methods with matching selectors to the supplied object
If you require the supplied object to be populated and/or selectors to be applied, use the
supply(TargetSelector, Generator)
method instead.- Type Parameters:
V
- type of the value to generate- Parameters:
selector
- for fields and/or classes this method should be applied tosupplier
- providing the value for given selector- Returns:
- API builder reference
- See Also:
-
supply
Supplies an object using aGenerator
to matching selector targets. By default, Instancio will populate uninitialised fields of the supplied object. This includes fields withnull
or default primitive values.This method supports the following use cases.
Generate random objects
This method provides an instance of
Random
that can be used to randomise generated objects. For example, if Instancio did not support creation ofjava.time.Year
, it could be generated as follows:List<Year> years = Instancio.ofList(Year.class) .supply(all(Year.class), random -> Year.of(random.intRange(1900, 2000))) .create();
Provide a partially initialised instance
In some cases, an object may need to be created in a certain state or instantiated using a specific constructor to be in a valid state. A partially initialised instance can be supplied using this method, and Instancio will populate remaining fields that are
null
:Person person = Instancio.of(Person.class) .supply(field(Person::getAddress), random -> new Address("Springfield", "USA")) .create();
This behaviour is controlled by the
AfterGenerate
hint specified byGenerator.hints()
. Refer to theGenerator.hints()
Javadoc for details, or Custom Generators section of the user guide.- Type Parameters:
V
- type of the value to generate- Parameters:
selector
- for fields and/or classes this method should be applied togenerator
- that will provide the values- Returns:
- API builder reference
- See Also:
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generate
Customises values using built-in generators provided by thegen
parameter, of typeGenerators
.Example:
Person person = Instancio.of(Person.class) .generate(field(Person::getAge), gen -> gen.ints().range(18, 100)) .generate(all(LocalDate.class), gen -> gen.temporal().localDate().past()) .generate(field(Address::getPhoneNumbers), gen -> gen.collection().size(5)) .generate(field(Address::getCity), gen -> gen.oneOf("Burnaby", "Vancouver", "Richmond")) .create();
- Type Parameters:
V
- type of object to generate- Parameters:
selector
- for fields and/or classes this method should be applied togen
- provider of customisable built-in generators (also known as specs)- Returns:
- API builder reference
- See Also:
-
generate
Customises values using arbitrary generator specs.Example:
Person person = Instancio.of(Person.class) .generate(field(Person::getAge), Instancio.ints().range(18, 100)) .generate(all(LocalDate.class), Instancio.temporal().localDate().past()) .generate(field(Phone::getNumber), MyCustomGenerators.phones().northAmerican()) .create();
- Type Parameters:
V
- type of object to generate- Parameters:
selector
- for fields and/or classes this method should be applied tospec
- generator spec- Returns:
- API builder reference
- Since:
- 2.6.0
- See Also:
-
onComplete
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 tocallback
- to invoke after object has been populated- Returns:
- API builder reference
- Since:
- 1.0.4
-
subtype
Maps target field or class to the given subtype. This can be used in the following cases:- to specify an implementation for interfaces or abstract classes
- to override default implementations used by Instancio
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
forList
. 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 allList
s.- Parameters:
selector
- for fields and/or classes this method should be applied tosubtype
- to map the selector to- Returns:
- API builder reference
- Since:
- 1.4.0
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withSettings
Override defaultSettings
for generating values. TheSettings
class supports various parameters, such as collection sizes, string lengths, numeric ranges, and so on. For a list of overridable settings, refer to theKeys
class.- Parameters:
settings
- to use- Returns:
- API builder reference
- Since:
- 1.0.1
- See Also:
-
withSeed
Sets the seed value for the random number generator. If the seed is not specified, a random seed will be used. Specifying the 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.create(UUID.class); // Generates the same UUID each time UUID result = Instancio.of(UUID.class) .withSeed(1234) .create();
- Parameters:
seed
- for the random number generator- Returns:
- API builder reference
- Since:
- 1.0.1
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lenient
InstancioApi<T> lenient()Disables strict mode in which unused selectors trigger an error. In lenient mode unused selectors are simply ignored.This method is a shorthand for:
Example example = Instancio.of(Example.class) .withSettings(Settings.create().set(Keys.MODE, Mode.LENIENT)) .create();
- Returns:
- API builder reference
- Since:
- 1.4.1
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