feat: adding mandatory flag to string input

- Added to flow
- Added to component
- Add simple test case
- Add samples

spring-shell-core/src/main/java/org/springframework/shell/component/StringInput.java

@@ -44,21 +44,28 @@ public class StringInput extends AbstractTextComponent<String, StringInputContex
 	private final String defaultValue;
 	private StringInputContext currentContext;
 	private Character maskCharacter;
+	private boolean mandatory;
 
 	public StringInput(Terminal terminal) {
-		this(terminal, null, null, null);
+		this(terminal, null, null, null, false);
 	}
 
 	public StringInput(Terminal terminal, String name, String defaultValue) {
-		this(terminal, name, defaultValue, null);
+		this(terminal, name, defaultValue, null, false);
 	}
 
 	public StringInput(Terminal terminal, String name, String defaultValue,
 			Function<StringInputContext, List<AttributedString>> renderer) {
+		this(terminal, name, defaultValue, renderer, false);
+	}
+
+	public StringInput(Terminal terminal, String name, String defaultValue,
+			Function<StringInputContext, List<AttributedString>> renderer, boolean mandatory) {
 		super(terminal, name, null);
 		setRenderer(renderer != null ? renderer : new DefaultRenderer());
 		setTemplateLocation("classpath:org/springframework/shell/component/string-input-default.stg");
 		this.defaultValue = defaultValue;
+		this.mandatory = mandatory;
 	}
 
 	/**
@@ -70,12 +77,21 @@ public void setMaskCharacter(Character maskCharacter) {
 		this.maskCharacter = maskCharacter;
 	}
 
+	/**
+	 * Sets a mandatory flag to check that the result is not empty
+	 *
+	 * @param mandatory if input is required
+	 */
+	public void setMandatory(boolean mandatory) {
+		this.mandatory = mandatory;
+	}
+
 	@Override
 	public StringInputContext getThisContext(ComponentContext<?> context) {
 		if (context != null && currentContext == context) {
 			return currentContext;
 		}
-		currentContext = StringInputContext.of(defaultValue, maskCharacter);
+		currentContext = StringInputContext.of(defaultValue, maskCharacter, mandatory);
 		currentContext.setName(getName());
 		context.stream().forEach(e -> {
 			currentContext.put(e.getKey(), e.getValue());
@@ -116,6 +132,9 @@ protected boolean read(BindingReader bindingReader, KeyMap<String> keyMap, Strin
 				}
 				else if (context.getDefaultValue() != null) {
 					context.setResultValue(context.getDefaultValue());
+				} else if (mandatory) {
+					context.setMessage("This field is mandatory", TextComponentContext.MessageLevel.ERROR);
+					break;
 				}
 				return true;
 			default:
@@ -175,13 +194,27 @@ public interface StringInputContext extends TextComponentContext<String, StringI
 		 */
 		Character getMaskCharacter();
 
+		/**
+		 * Sets flag for mandatory input.
+		 *
+		 * @param mandatory true if input is mandatory
+		 */
+		void setMandatory(boolean mandatory);
+
+		/**
+		 * Returns flag if input is required.
+		 *
+		 * @return true if input is required, false otherwise
+		 */
+		boolean isMandatory();
+
 		/**
 		 * Gets an empty {@link StringInputContext}.
 		 *
 		 * @return empty path input context
 		 */
 		public static StringInputContext empty() {
-			return of(null, null);
+			return of(null, null, false);
 		}
 
 		/**
@@ -190,7 +223,16 @@ public static StringInputContext empty() {
 		 * @return path input context
 		 */
 		public static StringInputContext of(String defaultValue, Character maskCharacter) {
-			return new DefaultStringInputContext(defaultValue, maskCharacter);
+			return of(defaultValue, maskCharacter, false);
+		}
+
+		/**
+		 * Gets an {@link StringInputContext}.
+		 *
+		 * @return path input context
+		 */
+		public static StringInputContext of(String defaultValue, Character maskCharacter, boolean mandatory) {
+			return new DefaultStringInputContext(defaultValue, maskCharacter, mandatory);
 		}
 	}
 
@@ -199,10 +241,12 @@ private static class DefaultStringInputContext extends BaseTextComponentContext<
 
 		private String defaultValue;
 		private Character maskCharacter;
+		private boolean mandatory;
 
-		public DefaultStringInputContext(String defaultValue, Character maskCharacter) {
+		public DefaultStringInputContext(String defaultValue, Character maskCharacter, boolean mandatory) {
 			this.defaultValue = defaultValue;
 			this.maskCharacter = maskCharacter;
+			this.mandatory = mandatory;
 		}
 
 		@Override
@@ -220,6 +264,11 @@ public void setMaskCharacter(Character maskCharacter) {
 			this.maskCharacter = maskCharacter;
 		}
 
+		@Override
+		public void setMandatory(boolean mandatory) {
+			this.mandatory = mandatory;
+		}
+
 		@Override
 		public String getMaskedInput() {
 			return maybeMask(getInput());
@@ -240,6 +289,11 @@ public Character getMaskCharacter() {
 			return maskCharacter;
 		}
 
+		@Override
+		public boolean isMandatory() {
+			return mandatory;
+		}
+
 		@Override
 		public Map<String, Object> toTemplateModel() {
 			Map<String, Object> attributes = super.toTemplateModel();
@@ -248,6 +302,7 @@ public Map<String, Object> toTemplateModel() {
 			attributes.put("maskedResultValue", getMaskedResultValue());
 			attributes.put("maskCharacter", getMaskCharacter());
 			attributes.put("hasMaskCharacter", hasMaskCharacter());
+			attributes.put("mandatory", isMandatory());
 			Map<String, Object> model = new HashMap<>();
 			model.put("model", attributes);
 			return model;

spring-shell-core/src/main/java/org/springframework/shell/component/flow/BaseStringInput.java

@@ -38,6 +38,7 @@ public abstract class BaseStringInput extends BaseInput<StringInputSpec> impleme
 	private ResultMode resultMode;
 	private String defaultValue;
 	private Character maskCharacter;
+	private boolean mandatory = false;
 	private Function<StringInputContext, List<AttributedString>> renderer;
 	private List<Consumer<StringInputContext>> preHandlers = new ArrayList<>();
 	private List<Consumer<StringInputContext>> postHandlers = new ArrayList<>();
@@ -79,6 +80,12 @@ public StringInputSpec maskCharacter(Character maskCharacter) {
 		return this;
 	}
 
+	@Override
+	public StringInputSpec mandatory() {
+		this.mandatory = true;
+		return this;
+	}
+
 	@Override
 	public StringInputSpec renderer(Function<StringInputContext, List<AttributedString>> renderer) {
 		this.renderer = renderer;
@@ -146,6 +153,10 @@ public Character getMaskCharacter() {
 		return maskCharacter;
 	}
 
+	public boolean isMandatory() {
+		return mandatory;
+	}
+
 	public Function<StringInputContext, List<AttributedString>> getRenderer() {
 		return renderer;
 	}
@@ -169,4 +180,4 @@ public boolean isStoreResult() {
 	public Function<StringInputContext, String> getNext() {
 		return next;
 	}
-}
+}

spring-shell-core/src/main/java/org/springframework/shell/component/flow/ComponentFlow.java

@@ -465,6 +465,7 @@ private Stream<OrderedInputOperation> stringInputsStream() {
 							if (input.getResultMode() == ResultMode.VERIFY && StringUtils.hasText(input.getResultValue())) {
 								selector.addPreRunHandler(c -> {
 									c.setDefaultValue(input.getResultValue());
+									c.setMandatory(input.isMandatory());
 								});
 							}
 							selector.addPostRunHandler(c -> {

spring-shell-core/src/main/java/org/springframework/shell/component/flow/StringInputSpec.java

@@ -72,6 +72,13 @@ public interface StringInputSpec extends BaseInputSpec<StringInputSpec> {
 	 */
 	StringInputSpec maskCharacter(Character maskCharacter);
 
+	/**
+	 * Sets input to mandatory
+	 *
+	 * @return a builder
+	 */
+	StringInputSpec mandatory();
+
 	/**
 	 * Sets a renderer function.
 	 *
@@ -128,4 +135,4 @@ public interface StringInputSpec extends BaseInputSpec<StringInputSpec> {
 	 * @return the parent builder
 	 */
 	Builder and();
-}
+}

spring-shell-core/src/main/resources/org/springframework/shell/component/string-input-default.stg

@@ -1,9 +1,23 @@
+// message
+message(model) ::= <%
+<if(model.message && model.hasMessageLevelError)>
+<({<figures.error>}); format="style-level-error"> <model.message; format="style-level-error">
+<elseif(model.message && model.hasMessageLevelWarn)>
+<({<figures.warning>}); format="style-level-warn"> <model.message; format="style-level-warn">
+<elseif(model.message && model.hasMessageLevelInfo)>
+<({<figures.info>}); format="style-level-info"> <model.message; format="style-level-info">
+<endif>
+%>
+
 // info section after '? xxx'
 info(model) ::= <%
 <if(model.hasMaskCharacter)>
   <if(model.maskedInput)>
     <model.maskedInput>
   <else>
+    <if(model.mandatory)>
+      <("[Mandatory]"); format="style-value">
+    <endif>
     <if(model.defaultValue)>
       <("[Default "); format="style-value"><model.defaultValue; format="style-value"><("]"); format="style-value">
     <endif>
@@ -12,6 +26,9 @@ info(model) ::= <%
   <if(model.input)>
     <model.input>
   <else>
+    <if(model.mandatory)>
+      <("[Mandatory]"); format="style-value">
+    <endif>
     <if(model.defaultValue)>
       <("[Default "); format="style-value"><model.defaultValue; format="style-value"><("]"); format="style-value">
     <endif>
@@ -32,6 +49,7 @@ result(model) ::= <<
 // component is running
 running(model) ::= <<
 <question_name(model)> <info(model)>
+<message(model)>
 >>
 
 // main

spring-shell-core/src/test/java/org/springframework/shell/component/StringInputTests.java

@@ -166,6 +166,39 @@ public void testResultUserInput() throws InterruptedException {
 		assertThat(run1Context.getResultValue()).isEqualTo("test");
 	}
 
+	@Test
+	public void testResultMandatoryInput() throws InterruptedException {
+		ComponentContext<?> empty = ComponentContext.empty();
+		StringInput component1 = new StringInput(getTerminal());
+		component1.setResourceLoader(new DefaultResourceLoader());
+		component1.setTemplateExecutor(getTemplateExecutor());
+		component1.setMandatory(true);
+
+		service.execute(() -> {
+			StringInputContext run1Context = component1.run(empty);
+			result1.set(run1Context);
+			latch1.countDown();
+		});
+
+		TestBuffer testBuffer = new TestBuffer().cr();
+		write(testBuffer.getBytes());
+
+		latch1.await(2, TimeUnit.SECONDS);
+
+		StringInputContext run1Context = result1.get();
+		assertThat(consoleOut()).contains("This field is mandatory");
+		assertThat(run1Context).isNull();
+
+		testBuffer.append("test").cr();
+		write(testBuffer.getBytes());
+
+		latch1.await(2, TimeUnit.SECONDS);
+		run1Context = result1.get();
+
+		assertThat(run1Context).isNotNull();
+		assertThat(run1Context.getResultValue()).isEqualTo("test");
+	}
+
 	@Test
 	public void testPassingViaContext() throws InterruptedException {
 		ComponentContext<?> empty = ComponentContext.empty();

spring-shell-core/src/test/java/org/springframework/shell/component/flow/ComponentFlowTests.java

@@ -52,6 +52,10 @@ public void testSimpleFlow() throws InterruptedException {
 				.withStringInput("field2")
 					.name("Field2")
 					.and()
+				.withStringInput("field3")
+					.name("Field3")
+					.mandatory()
+					.and()
 				.withPathInput("path1")
 					.name("Path1")
 					.and()
@@ -80,6 +84,9 @@ public void testSimpleFlow() throws InterruptedException {
 		// field2
 		testBuffer = new TestBuffer().append("Field2Value").cr();
 		write(testBuffer.getBytes());
+		// field2
+		testBuffer = new TestBuffer().cr().append("Field3Value").cr();
+		write(testBuffer.getBytes());
 		// path1
 		testBuffer = new TestBuffer().append("fakedir").cr();
 		write(testBuffer.getBytes());
@@ -95,10 +102,12 @@ public void testSimpleFlow() throws InterruptedException {
 		assertThat(inputWizardResult).isNotNull();
 		String field1 = inputWizardResult.getContext().get("field1");
 		String field2 = inputWizardResult.getContext().get("field2");
+		String field3 = inputWizardResult.getContext().get("field3");
 		Path path1 = inputWizardResult.getContext().get("path1");
 		String single1 = inputWizardResult.getContext().get("single1");
 		List<String> multi1 = inputWizardResult.getContext().get("multi1");
 		assertThat(field1).isEqualTo("defaultField1Value");
+		assertThat(field3).isEqualTo("Field3Value");
 		assertThat(field2).isEqualTo("Field2Value");
 		assertThat(path1.toString()).contains("fakedir");
 		assertThat(single1).isEqualTo("value1");

spring-shell-docs/src/main/asciidoc/using-shell-components-ui-stringinput.adoc

@@ -3,7 +3,8 @@
 ifndef::snippets[:snippets: ../../test/java/org/springframework/shell/docs]
 
 The string input component asks a user for simple text input, optionally masking values
-if the content contains something sensitive. The following listing shows an example:
+if the content contains something sensitive. The input can also be required (at least 1 char). +
+The following listing shows an example:
 
 ====
 [source, java, indent=0]
@@ -38,6 +39,9 @@ The context object is `StringInputContext`. The following table lists its contex
 |`hasMaskCharacter`
 |`true` if a mask character is set. Otherwise, false.
 
+|`mandatory`
+|`true` if the input is required. Otherwise, false.
+
 |`model`
 |The parent context variables (see <<textcomponentcontext-template-variables>>).
 |===

spring-shell-samples/src/main/java/org/springframework/shell/samples/standard/ComponentCommands.java

@@ -56,6 +56,15 @@ public String stringInput(boolean mask) {
 		return "Got value " + context.getResultValue();
 	}
 
+	@ShellMethod(key = "component string required", value = "String input", group = "Components")
+	public String stringRequired() {
+		StringInput component = new StringInput(getTerminal(), "Enter value", null, null, true);
+		component.setResourceLoader(getResourceLoader());
+		component.setTemplateExecutor(getTemplateExecutor());
+		StringInputContext context = component.run(StringInputContext.empty());
+		return "Got value " + context.getResultValue();
+	}
+
 	@ShellMethod(key = "component path", value = "Path input", group = "Components")
 	public String pathInput() {
 		PathInput component = new PathInput(getTerminal(), "Enter value");

spring-shell-samples/src/main/java/org/springframework/shell/samples/standard/ComponentFlowCommands.java

@@ -62,6 +62,10 @@ public void showcase1() {
 				.withStringInput("field2")
 					.name("Field2")
 					.and()
+				.withStringInput("field3")
+					.name("Field3")
+					.mandatory()
+					.and()
 				.withConfirmationInput("confirmation1")
 					.name("Confirmation1")
 					.and()