= Tabular Extension

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The Tabular Extension module integrates with the xref:vw:ROOT:about.adoc[Wicket Viewer] to allow any collection to be downloaded as specific tabular data file (e.g. an Excel spreadsheet).

The viewer automatically makes the "download" menu item available for all tables:

image::screenshot.png[width=300px]

== Setup

=== Dependency Management

In your application's top level `pom.xml`, add a dependency for this module's own bill of materials (BOM):

[source,xml,subs="attributes+"]
.pom.xml
----
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.apache.causeway.extensions</groupId>
            <artifactId>causeway-extensions-tabular</artifactId>
            <scope>import</scope>
            <type>pom</type>
            <version>{page-causewayprevv3}</version>
        </dependency>
    </dependencies>
</dependencyManagement>
----

=== Dependencies / Imports

In the webapp module of your application, add the following dependency:

[source,xml]
.pom.xml
----
<dependency>
    <groupId>org.apache.causeway.extensions</groupId>
    <artifactId>causeway-extensions-tabular-excel</artifactId>
</dependency>
----

In your application's xref:userguide::modules.adoc#appmanifest[App Manifest], import the extension's implementation module:

[source,java]
.AppManifest.java
----
@Configuration
@Import({
        CausewayModuleExtTabularExcel.class,
        ...
})
public class AppManifest {
}
----

== Custom Export (SPI)

To provide a custom exporter, simply implement `CollectionContentsExporter` and register with _Spring_.

[source, java]
.Collection Contents Exporter (SPI)
----
/**
 * SPI to provide file export to table views.
 *
 * @since 2.0 {@index}}
 */
public interface CollectionContentsExporter {

    File createExportFile(DataTable dataTable);

    CommonMimeType getMimeType();

    /**
     * @return label for the "View as" dropdown for "collection contents as"
     * component factories
     */
    String getTitleLabel();

    /**
     * @return CSS class for the icon/image next to "View as" dropdown
     * for "collection contents as" component factories
     */
    String getCssClass();

    /**
     * An ordinal, that governs the order of appearance in the UI dropdown.
     * <ul>
     * <li>{@literal 1000..1999} reserved for different table presentations</li>
     * <li>{@literal 2000..2999} reserved for different table exports</li>
     * </ul>
     * <p>
     * Lowest comes first.
     */
    int orderOfAppearanceInUiDropdown();

    /**
     * Whether activation of this table presentation view should result in a full page reload.
     */
    default boolean isPageReloadRequiredOnTableViewActivation() { return false; }
}
----
