fix(core): allow null val for optional input with default (#11819)

Handles multipart 'null' string as null (no value) for the input

Fixes: #11819

core/src/main/java/io/kestra/core/runners/FlowInputOutput.java

@@ -130,7 +130,7 @@ public class FlowInputOutput {
     private Mono<Map<String, Object>> readData(List<Input<?>> inputs, Execution execution, Publisher<CompletedPart> data, boolean uploadFiles) {
         return Flux.from(data)
             .publishOn(Schedulers.boundedElastic())
-            .<AbstractMap.SimpleEntry<String, String>>handle((input, sink) -> {
+            .<Map.Entry<String, String>>handle((input, sink) -> {
                 if (input instanceof CompletedFileUpload fileUpload) {
                     boolean oldStyleInput = false;
                     if ("files".equals(fileUpload.getName())) {
@@ -150,7 +150,7 @@ public class FlowInputOutput {
                             .getContextStorageURI()
                         );
                         fileUpload.discard();
-                        sink.next(new AbstractMap.SimpleEntry<>(inputId, from.toString()));
+                        sink.next(Map.entry(inputId, from.toString()));
                     } else {
                         try {
                             final String fileExtension = FileInput.findFileInputExtension(inputs, fileName);
@@ -165,7 +165,7 @@ public class FlowInputOutput {
                                     return;
                                 }
                                 URI from = storageInterface.from(execution, inputId, fileName, tempFile);
-                                sink.next(new AbstractMap.SimpleEntry<>(inputId, from.toString()));
+                                sink.next(Map.entry(inputId, from.toString()));
                             } finally {
                                 if (!tempFile.delete()) {
                                     tempFile.deleteOnExit();
@@ -178,13 +178,13 @@ public class FlowInputOutput {
                     }
                 } else {
                     try {
-                        sink.next(new AbstractMap.SimpleEntry<>(input.getName(), new String(input.getBytes())));
+                        sink.next(Map.entry(input.getName(), new String(input.getBytes())));
                     } catch (IOException e) {
                         sink.error(e);
                     }
                 }
             })
-            .collectMap(AbstractMap.SimpleEntry::getKey, AbstractMap.SimpleEntry::getValue);
+            .collectMap(Map.Entry::getKey, Map.Entry::getValue);
     }
 
     /**
@@ -334,7 +334,7 @@ public class FlowInputOutput {
             }
 
             // validate and parse input value
-            if (value == null) {
+            if (value == null || "NULL".equals(value.toString().toUpperCase(Locale.ROOT))) {
                 if (input.getRequired()) {
                     resolvable.resolveWithError(input.toConstraintViolationException("missing required input", null));
                 } else {

core/src/test/java/io/kestra/core/runners/FlowInputOutputTest.java

@@ -19,6 +19,7 @@ import io.micronaut.http.multipart.CompletedFileUpload;
 import io.micronaut.http.multipart.CompletedPart;
 import io.micronaut.test.annotation.MockBean;
 import jakarta.inject.Inject;
+import jakarta.validation.ConstraintViolationException;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.reactivestreams.Publisher;
@@ -34,6 +35,7 @@ import java.util.Map;
 import java.util.Optional;
 
 import static io.kestra.core.tenant.TenantService.MAIN_TENANT;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
 
 @KestraTest
 class FlowInputOutputTest {
@@ -335,6 +337,44 @@ class FlowInputOutputTest {
         Assertions.assertEquals(TEST_SECRET_VALUE, results.get("input"));
     }
     
+    @Test
+    void shouldNotGetDefaultWhenPassingNullForNotRequiredInput() {
+        // Given
+        StringInput input = StringInput.builder()
+            .id("input")
+            .type(Type.STRING)
+            .defaults(Property.ofValue("default"))
+            .required(false)
+            .build();
+        
+        Mono<CompletedPart> data = Mono.just(new MemoryCompletedPart("input", "null".getBytes(StandardCharsets.UTF_8)));
+        
+        // When
+        Map<String, Object> results = flowInputOutput.readExecutionInputs(List.of(input), null, DEFAULT_TEST_EXECUTION, data).block();
+        
+        // Then
+        Assertions.assertNull(results.get("input"));
+    }
+    
+    @Test
+    void shouldNotGetErrorWhenPassingNullForRequiredInput() {
+        // Given
+        StringInput input = StringInput.builder()
+            .id("input")
+            .type(Type.STRING)
+            .defaults(Property.ofValue("default"))
+            .required(true)
+            .build();
+        
+        Mono<CompletedPart> data = Mono.just(new MemoryCompletedPart("input", "null".getBytes(StandardCharsets.UTF_8)));
+        
+        // When
+        ConstraintViolationException exception = Assertions.assertThrows(ConstraintViolationException.class, () ->
+            flowInputOutput.readExecutionInputs(List.of(input), null, DEFAULT_TEST_EXECUTION, data).block()
+        );
+        assertThat(exception.getMessage()).isEqualTo("input: Invalid input for `input`, missing required input, but received `null`");
+    }
+    
     private static class MemoryCompletedPart implements CompletedPart {
         
         protected final String name;

ui/src/utils/submitTask.js

@@ -5,9 +5,14 @@ export const inputsToFormData = (submitor, inputsList, values) => {
     let inputValuesCloned = _cloneDeep(values)
 
     for (const input of inputsList || []) {
-        if (inputValuesCloned[input.id] === undefined || inputValuesCloned[input.id] === "") {
+        if (inputValuesCloned[input.id] === undefined) {
             delete inputValuesCloned[input.id];
         }
+        
+        // Input was explicitly filled with empty string
+        if (inputValuesCloned[input.id] === "") {
+            inputValuesCloned[input.id] = undefined;
+        }
 
         // Required to have "undefined" value for boolean
         if (input.type === "BOOLEAN" && inputValuesCloned[input.id] === "undefined") {
@@ -34,6 +39,8 @@ export const inputsToFormData = (submitor, inputsList, values) => {
             } else {
                 formData.append(inputName, inputValue);
             }
+        } else if (input.type !== "BOOLEAN") {
+            formData.append(inputName, null);
         }
     }