4.2.3.1. Views Creation

A view can be created in two possible ways:

  • Programmatically – by creating View instance, for example: 

    View view = new View(Order.class)
        .addProperty("date")
        .addProperty("amount")
        .addProperty("customer", new View(Customer.class)
            .addProperty("name")
        );

    Typically, this way can be appropriate for creating views that are used in a single piece of business-logic.

  • Declaratively – by creating an XML descriptor and deploying it to ViewRepository. View instances are created and cached when XML-based descriptor is deployed. Further on the required view can be retrieved in any part of the application code by repository call providing the entity class and view name.

Let us consider in details the declarative way for creation and working with views.

ViewRepository is a Spring bean, accessible to all application blocks. The link to ViewRepository can be obtained using Metadata infrastructure interface. getView() methods are used to retrieve View instance from the repository. deployViews() methods from AbstractViewRepository basic implementation are used to deploy XML view descriptors to the repository.

Two views named _local and _minimal are available in the repository for each entity by default:

  • _local contains all local entity attributes.

  • _minimal contains the attributes which are included to the name of the entity instance and which are specified by @NamePattern annotation. If @NamePattern annotation is not specified in the entity, this view does not contain any attributes.

The detailed structure of XML descriptors is provided in Section A.11, “views.xml”.

The example below shows view descriptor for Order entity which provides loading of all local attributes, associated Customer and ordered Items collection: 

<view class="com.sample.sales.entity.Order"
      name="orderWithCustomer"
      extends="_local">
    <property name="customer" view="_minimal"/>
    <property name="items" view="itemsInOrder"/>
</view>

The recommended way of grouping and deployment of view descriptors is as follows:

  • Create views.xml file in the global module in src root and place all view descriptors which should be globally accessible (i.e. on all application tiers into it.

  • Register this file in cuba.viewsConfig application property of all used blocks, i.e. in app.properties of the core module, web-app.properties of the web module, etc. This will ensure automatic deployment of the views upon application startup in the repository (See AbstractViewRepository.init() method).

  • If there are views which are used only in one application block, they can be specified in the similar file in this block, for example, web-views.xml, and registered in cuba.viewsConfig property of this block only.

    If the repository contains a view with certain name for some entity, an attempt to deploy another view with this name for the same entity will be ignored. If you need to replace the existing view in the repository with a new one and guarantee its deployment, specify overwrite = "true" attribute for it.

It is recommended to give “descriptive” names to the views. For example, not just “browse”, but “customerBrowse”. It simplifies the search of views in XML descriptors.

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