Single Select

A single select component asks a user to choose one item from a list. It is similar to a simple dropbox implementation. The following listing shows an example:spring-doc.cn

@ShellComponent
public class ComponentCommands extends AbstractShellComponent {

	@ShellMethod(key = "component single", value = "Single selector", group = "Components")
	public String singleSelector() {
		SelectorItem<String> i1 = SelectorItem.of("key1", "value1");
		SelectorItem<String> i2 = SelectorItem.of("key2", "value2");
		List<SelectorItem<String>> items = Arrays.asList(i1, i2);
		SingleItemSelector<String, SelectorItem<String>> component = new SingleItemSelector<>(getTerminal(),
				items, "testSimple", null);
		component.setResourceLoader(getResourceLoader());
		component.setTemplateExecutor(getTemplateExecutor());
		SingleItemSelectorContext<String, SelectorItem<String>> context = component
				.run(SingleItemSelectorContext.empty());
		String result = context.getResultItem().flatMap(si -> Optional.ofNullable(si.getItem())).get();
		return "Got value " + result;
	}
}

The following screencast shows typical output for a single select component:spring-doc.cn

The context object is SingleItemSelectorContext. The following table describes its context variables:spring-doc.cn

Table 1. SingleItemSelectorContext Template Variables
Key	Description
`value`spring-doc.cn	The returned value when the component exists.spring-doc.cn
`rows`spring-doc.cn	The visible items, where rows contains maps of name and selected items.spring-doc.cn
`model`spring-doc.cn	The parent context variables (see SelectorComponentContext Template Variables).spring-doc.cn

You can pre-select an item by defining it to get exposed. This is useful if you know the default and lets the user merely press Enter to make a choice. The following listing sets a default:spring-doc.cn

SelectorItem<String> i1 = SelectorItem.of("key1", "value1");
SelectorItem<String> i2 = SelectorItem.of("key2", "value2");
List<SelectorItem<String>> items = Arrays.asList(i1, i2);
SingleItemSelector<String, SelectorItem<String>> component = new SingleItemSelector<>(getTerminal(),
		items, "testSimple", null);
component.setDefaultExpose(i2);