Java annotations database schema code#
Java annotations database schema plus#

JAXB/MOXy is not always the most effective way to map JPA to XML. It offers superior performance in several mapping scenarios.įor more information on MOXy, see the MOXy FAQ at: It allows you to combine MOXy mappings and the TopLink persistence framework to interact with your data through the J2EE connector architecture (JCA). It allows you to map your existing JPA models to industry standard schemas. It offers specific features, such as compound key mapping and mapping relationships with back-pointers to address critical JPA-to-XML mapping issues. This avoids static coupling of your mapped classes with a single XML schema.

It allows you to map your own classes to your own XML schema, a process called 'Meet in the Middle Mapping'. Because MOXy represents the optimal JAXB implementation, you still implement it whether or not you explicitly use any of its extensions. You can use these latter annotations in conjunction with the standard annotations to extend the utility of JAXB.

Java annotations database schema plus#

MOXy supports all the standard JAXB annotations in the package plus has its own extensions in the .annotations package. It allows you to map a Plain Old Java Objects (POJO) model to an XML schema, greatly enhancing your ability to create JPA-to-XML mappings. For more information on these annotations, see Oracle Fusion Middleware Java API Reference for Oracle TopLink.įor more information about JAXB, see 'Java Architecture for XML Binding (JAXB)' at: These annotations are subclasses of the. JAXB uses an extended set of annotations to define the binding rules for Java-to-XML mapping. This service provides a means to access data exposed by JPA across computers, where the client computer might or might not be using Java. Both of these web service standards use JAXB as the default binding layer. Usually, an XML binding is used with JPA entities to create a data access service by optimizing a JAX-WS or JAX-RS implementation. In this way, applications can access the data in the XML from the object rather than using the Domain Object Model (DOM) or the Streaming API for XML (SAX) to retrieve the data from a direct representation of the XML itself. This process, called binding, represents information in an XML document as an object in computer memory. But it's not always the case that the names of the classes match the names of the tables in your database.JAXB is a Java API that allows a Java program to access an XML document by presenting that document to the program in a Java format.

Java annotations database schema code#

You can use Code First with an existing database. If you are letting Code First create the database, and also want to change the name of the tables it is creating. Tableĭefault Code First convention creates a table name similar to the class name. If the user sets the Title which contains more than 24 characters, then EF will throw EntityValidationError. Public DateTime EnrollmentDate Įntity Framework also validates the value of a property for StringLength attribute. So to handle this, a Key attribute is added which will make it a primary key. Let’s take a look at the following code of a Student class which contains StdntID, but it doesn’t follow the default Code First convention. You can use the key annotation to specify which property is to be used as the EntityKey. When Code First does not find a property that matches this convention, it will throw an exception because of Entity Framework’s requirement that you must have a key property. Now let’s suppose Student class used the name StdntID instead of ID.

The Student, Course and Enrollment classes follow this convention. The property will map to a primary key column in the database. One of the conventions that Code First depends on is how it implies which property is the key in each of the Code First classes.Ĭonvention is to look for a property named “Id” or one that combines the class name and “Id”, such as “StudentId”. namespace includes the following attributes that impacts the schema of the database.Įntity Framework relies on every entity having a key value that it uses for tracking entities. includes the following attributes that impacts the nullability or size of the column. DataAnnotation attributes override default CodeFirst conventions. NET applications, such as ASP.NET MVC which allows these applications to leverage the same annotations for client-side validations.

DataAnnotations are also understood by a number of. DataAnnotations is used to configure the classes which will highlight the most commonly needed configurations.