According to the example the screen includes the description of customerDc data container for a Customer entity with active attribute. Use the value attribute to specify values and the ref attribute to specify identifiers of the screen components. InitEvent is sent when the screen controller and all its declaratively defined components are created, and dependency injection is completed. Some visual components are not fully initialized, for example buttons are not linked with actions.
2.4. Spring Beans
Entity meta-annotations are a set of key/value pairs providing additional information about entities. Studio allows you to set format strings for languages used in your application. Edit Project Properties, click the button in the Available locales field, then click Show data format strings. Parsing formats ignoring locale are hardcoded or specified in the metadata.xml file when registering the datatype. Meta-classes are grouped by the root name of Java project package specified in metadata.xml file. @OnDeleteInverse annotation is processed when the entity which it points to is deleted (which is similar to cascade deletion at foreign key level in the database).
1.3. Application Components
Read-only transactions yield better performance because the platform does not execute code that handles possible entity modifications. Any method of the Middleware Spring bean may be annotated with @org.springframework.transaction.annotation.Transactional, which will automatically create a transaction when the method is called. Such method does not require invoking Persistence.createTransaction(), you can immediately get EntityManager and work with it. The JPQL DELETE FROM statement throws an exception if launched for the soft-deleted entity and the Soft Delete mode is on.
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For example, cuba.persistenceConfig should be an additive property. In your project, it specifies a persistence.xml file defining your project’s data model. AuthenticationManager login / authenticate methods return AuthenticationDetails instance which contains UserSession object.
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- The interface containing methods for conversion between data model attribute values and parameters/results of JDBC queries.
- Language selection options are determined by the combination of cuba.localeSelectVisible and cuba.availableLocales application properties.
- In particular, this applies to attributes of the UUID type – only the PostgreSQL driver returns values of corresponding columns using this type; other servers return String.
- An additive property value obtained at runtime is formed by elements concatenated with a space symbol.
- @MetaProperty annotation is required if @Transient attribute should be included in metadata.
And for the Order editor screen, you need to fetch the collection of Items, in addition to that each Item should contain a related Product instance to display its name. Determines the order of elements in a collection attribute at the point when the association is retrieved from the database. This annotation should be specified for ordered Java collections such as List or LinkedHashSet to get a predictable sequence of elements. Determines related entities handling policy in case of soft deletion of the entity, containing the attribute. Indicates that automatic case conversion should be used for text input fields bound with annotated entity attribute. Indicates that EntityChangedEvent should be sent by the framework when the entity is changed in the database.
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If you implement the DataStore interface in your project, the name of the implementation bean must be specified in the cuba.storeImpl_ application property. DataService provides a facade for calling DataManager middleware implementation from the client tier. The usage of DataService interface in the application code is not recommended. Instead, use DataManager directly on both middle and client tiers. The proxy object factory is configured in spring.xml of the corresponding client block and contains service names and interfaces. ServiceInterceptor is called automatically for any service method using Spring AOP.
2.6. Infrastructure Interfaces
An order in which files are declared is important because the values, specified in each subsequent file override the values of the properties with the same name, specified in the preceding files. If you omit + for a property, its value will be obtained only from the current project. It can be useful if sell mobile proxies you don’t want to inherit some configuration from components, for example, when you define a menu structure. For example, a value specified in a properties file overrides the value specified in the database. You can affect the order of listeners invocation by specifying the @Order annotation. The Events.HIGHEST_PLATFORM_PRECEDENCE and Events.LOWEST_PLATFORM_PRECEDENCE constants define the range which is used by listeners defined in the platform.
4.6. Entity and Query Cache
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See the Persistence interface methods and @Transactional annotation parameters for details. Such properties should be made additive by specifying the plus sign in the beginning of their values. This sign indicates that the property value will be assembled from application components at runtime.
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Transaction listeners are designed to react on transaction lifecycle events. Unlike entity listeners, they are not tied to an entity type and invoked for each transaction. If the persistence context of a read-only transaction contains modified entities, IllegalStateException will be thrown on attempt to commit the transaction. It means that you should mark a transaction as read-only only when you are sure that it doesn’t modify any entity. The createTransaction() method creates a new transaction and returns the Transaction interface.
- Use the value attribute to specify values and the ref attribute to specify identifiers of the screen components.
- The orphanRemoval annotation attribute does not respect the soft deletion mechanism.
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- See the Persistence interface methods and @Transactional annotation parameters for details.
- Cache of the compiled classes can be cleaned at runtime using CachingFacadeMBean JMX bean.
2.4. Spring Beans
All imported services should be declared in the single remoteServices property in the map/entry elements. Recommendations for usage of the server DB update mechanism can be found in Creating and Updating Database in Production. PostgreSQL and Microsoft SQL Server support connection to a specific database schema. By default, the schema is public on PostgreSQL and dbo on SQL Server.
Nearly half of these connections had at least one packet loss, mostly SYNs and SYN-ACKs. Most TCP implementations use an RTO of 1 second for SYN packets, which increases exponentially for subsequent losses. Application load times can increase because TCP takes longer to establish connections. To combat bandwidth fluctuation and loss, cellular networks typically use large buffers for bursts of traffic. Very often, TCP treats such queuing as a loss due to an extended timeout, so TCP tends to do a relay and thus fill the buffer. This problem is known as bufferbloat (excessive network buffering, buffer swelling) and this is very serious problem modern internet.
2.9. Application Properties
The retrieved instance of EntityManager is bound to the current transaction, i.e. all calls to getEntityManager() as part of one transaction return one and the same instance of EntityManager. After the end of the transaction using the corresponding EntityManager instance is impossible. If you have any performance issues with the database access, the first thing to check is what SQL statements are actually executed.
- In the service, you can check permissions using the Security interface and return data to the client in the form of persistent or non-persistent entities or arbitrary values.
- The retrieved instance of EntityManager is bound to the current transaction, i.e. all calls to getEntityManager() as part of one transaction return one and the same instance of EntityManager.
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- Using this annotation for a specific entity class is required only in case of inheritance from the BaseStringIdEntity base class (i.e. creating an entity with a string primary key).
- The listener can be used to enforce complex business rules involving multiple entities.
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- For example, you may want to force a user to enter a value for an entity attribute, but at the same time to have an ability to set this attribute to null by some internal mechanism.
- You can create you own domain-specific constraints with programmatic or declarative validation.
- If @Lob is set, the default or explicitly defined length in @Column is ignored.
- These interfaces are implemented using the Vaadin framework components.
- Do not create any implementation classes because the platform will create a required proxy automatically when you inject the configuration interface or obtain it through Configuration.
- The Calendar component is intended to organize and display calendar events.
If it’s true, programmatic changes to the components state (if any) will be lost. When the method is invoked automatically on screen opening, the value of this parameter is false. But when invoking the method in response of UI events, set it to true, otherwise the restrictions on components will be summed and not replaced. The security subsystem allows you to set up access to entity attributes according to user permissions. That is the framework can automatically make an attribute read-only or hidden depending on a set of roles assigned to the current user. But sometimes you may want to change the access to attributes dynamically depending also on the current state of the entity or its linked entities.
2.2. Metadata Framework
Script sorting is performed by path, starting with the first subdirectory of the type or type-version directory, i.e. regardless of the directory where the script is located (versioned or not). Usually, all the work to convert the data between the database and the Java code is performed by the ORM layer in conjunction with the appropriate JDBC driver. It means that no manual conversion is required when working with the data using DataManager, EntityManager and JPQL queries; you should simply use Java types listed in the left column of the table. Database-related components belong to the Middleware block; other blocks of the application do not have direct access to the database. Generic UI components connected to a datasource get an instance of BeanValidator to check the field value.
Of course, application components can be reusable and provide a domain-specific layer of abstraction on top of the framework. A screen fragment can have its own data containers and loaders, defined in the data XML element. At the same time, the framework creates a single instance of DataContext for the screen and all its fragments.
