person

.fullName.startsWith("John")// basic string conditions

.fullName.isEqualTo(3.1415D)// will not compile since fullName is String

.fullName.isEqualTo(3.1415D)//ERROR!will not compile since fullName is String (not double)

.nickName.isAbsent()// for Optional attribute

.or()// disjunction

.age.isGreaterThan(21)

Not all entities require repository (`@Criteria.Repository`) but you need to add`@Criteria` to all classes you want to query by. For example, to filter on`Person.pets.name``Pet` class needs to have`@Criteria` (otherwise`PersonCriteria.pets` will have a very generic Object matcher).

`@Criteria.Repository` instructs immutables to generate repository class with`find` /`insert` /`watch` operations. You are required to provide a valid[backend](https://github.com/immutables/immutables/blob/master/criteria/common/src/org/immutables/criteria/adapter/Backend.java)

`@Criteria.Repository` instructs immutables to generate repository class with`find` /`insert` /`watch` operations. You are required to provide a valid[backend](https://github.com/immutables/immutables/blob/master/criteria/common/src/org/immutables/criteria/backend/Backend.java)

instance (mongo, elastic, inmemory etc).

Publisher<Person> result= repository.find(person.fullName.contains("Smith")).fetch();

-**Matcher** Typed predicate on a particular attribute. There are several variations of the matcher and, usually, they're

associated with a type (eg.

[StringMatcher](https://github.com/immutables/immutables/blob/master/criteria/common/src/org/immutables/criteria/matcher/StringMatcher.java),

[IterableMatcher](https://github.com/immutables/immutables/blob/master/criteria/common/src/org/immutables/criteria/matcher/IterableMatcher.java),

[ComparableMatcher](https://github.com/immutables/immutables/blob/master/criteria/common/src/org/immutables/criteria/matcher/ComparableMatcher.java)).

Matcher internally builds an_Expression_.

-**Expression** Abstraction of a generic expression modeled as

[Abstract Syntax Tree](https://en.wikipedia.org/wiki/Abstract_syntax_tree). Used internally as Intermediate Representation (IR)

to transform original expression into a native query of a database. Users rarely have to deal with this API unless

they write adapters for a particular backend.

-**Backend** adapter to a data-source (database). Responsible for interpreting expressions and operations into native

queries and API calls using vendor drivers.

-**Repository** User facing API to perform queries, updates, pub/sub or other CRUD operations. Uses_Backend_.

-**Facet** Property of repository to fine-tune its behaviour. Eg.`Readable` /`Writable` /`Watchable`

Also one can define return types based on[rxjava](https://github.com/ReactiveX/RxJava) /

async ([CompletionStage](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletionStage.html))

or synchronous types.

`common` module contains runtime support. Remaining folders are backend implementation.

`common` module contains runtime support. Remaining folders are backendand facetimplementation.

This folder contains classes specific to Criteria API and its runtime evaluation:

3.`mongo` adapter for[MongoDB](https://www.mongodb.com/)

based on[reactive streams](https://mongodb.github.io/mongo-java-driver-reactivestreams/) driver.

4.`geode` adapter for[Apache Geode](https://geode.apache.org)

5.`inmemory` lightweight implementation of a backend based on existing Map

5.`inmemory` lightweight implementation of a backend based on existing Map.

6.`rxjava`[rxjava](https://github.com/ReactiveX/RxJava) repository facets.

Criteria API requires Java 8 (or later)