!> Note: this library is under active development, breaking changes may occur
Path is a simple java utility for providing strongly typed references to nested methods and fields. It uses a convienent java 8 syntax for reflection, evaluation, and assertion. Path builds on Jodd's excellent (and very fast) Proxetta library.
Add the following dependency to your maven project. Gradle and others are also supported.
<dependency>
<groupId>io.devnet.util</groupId>
<artifactId>util-path</artifactId>
<version>0.5.0</version>
</dependency>Resolve the property path using getters
String path = Path.for(Album.class)
.$(Album::getArtist)
.$(Artist::getGenre)
.$(Genre::getName)
.resolve();
System.out.println(path); genreShorthand syntax (max depth 5)
String path = Path.for(Album::getArtist, Artist::getGenre, Genre::getName).resolve();
System.out.println(path); // artist.genere.nameResolve property path using fields
String path = Path.for(Album.class)
.$(album -> album.artist)
.$(artist -> artist.genre)
.$(genre -> genre.name)
.resolve();
System.out.println(path); // artist.genere.nameShorthand syntax (max depth 5)
String path = Path.for(a -> a.artist, a -> a.genre, g -> g.name).resolve();
System.out.println(path); // artist.genere.nameCreate the path chain
Path path = Path.for(Album.class).$(Album::getArtist).$(Artist::getGenere);Return a string representation of the chain
String fieldPath = path.resolve(); // "artist.genere.name"
// include the parent in the path
String fullPath = path.resolve(Path.RESOLVE_PARENT); // "album.artist.genre.name"Return a java.lang.reflect object for the last method in the chain. Throws MethodNotFound exception if the chain is built with fields.
Method method = path.lastMethod(); // getGenere()Return the type of the last field in the chain
Class<?> field = path.lastField(); // String.class, return type of getGenere()Retrieve the value for the last field in the chain by passing an instance of the parent class. The getters will be invoked if they are present in the chain.
Album album = myService.getAlbum();
String value = path.evaluate(album); // "synthwave", return of the last method in the chain: getGenere()This syntax allows implementations to both enforce the paths used in joins are correct and ensure that the input passed to the criteria is of the right type.
In this example Employee must have a method named getDepartment, department must have a method named getName, and departmentName of the same type as Department$getName's return type.
String departmentName = "accounting";
// shorthand
SearchResult<Employee> result = searchService.find(Employee.class)
.eq(Employee::getDepartment, Department::getName, departmentName)
.find();
// criteria approach
SearchCriteria<Employee> criteriaOne = SearchCriteria.for(Employee.class)
.$(Employee::getDeplartment)
.$(Department::getName)
.eq(departmentName);
// or
SearchCriteria<Employee> criteriaTwo = SearchCriteria.for(Employee.class)
.eq(Employee::getDeplartment, Department::getName, departmentName);
SearchResult<Employee> result = searchService.find(criteriaOne)A classic implementation may appear as follows. Here we do not know if the entities fields are and input types are valid until runtime.
String departmentName = "accounting";
// shorthand
SearchResult<Employee> result = searchService.find(Employee.class)
.eq("department.name", departmentName) // method params String, Object
.find();
// criteria approach
SearchCriteria<Employee> criteriaTwo = SearchCriteria.for(Employee.class)
.eq("department.name", departmentName); // method params: String, Object
SearchResult<Employee> result = searchService.find(criteriaOne);Path provides a convient syntax on top of Jodd's MethodRef for chaining multiple references together. The method are never invoked.
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