Add internal state validators for HasValue (#9532)

This also fixes/improves AbstractDateField validation.

3 files changed, 36 insertions, 2 deletions

diff --git a/server/src/main/java/com/vaadin/data/Binder.java b/server/src/main/java/com/vaadin/data/Binder.java
index 26720a3274..ae467be123 100644
--- a/server/src/main/java/com/vaadin/data/Binder.java
+++ b/server/src/main/java/com/vaadin/data/Binder.java
@@ -1190,7 +1190,8 @@ public class Binder<BEAN> implements Serializable {
         getStatusLabel().ifPresent(label -> label.setValue(""));
 
         return createBinding(field, createNullRepresentationAdapter(field),
-                this::handleValidationStatus);
+                this::handleValidationStatus)
+                        .withValidator(field.getDefaultValidator());
     }
 
     /**
diff --git a/server/src/main/java/com/vaadin/data/HasValue.java b/server/src/main/java/com/vaadin/data/HasValue.java
index 935f365e10..aad436a089 100644
--- a/server/src/main/java/com/vaadin/data/HasValue.java
+++ b/server/src/main/java/com/vaadin/data/HasValue.java
@@ -292,4 +292,19 @@ public interface HasValue<V> extends Serializable {
     public default void clear() {
         setValue(getEmptyValue());
     }
+
+    /**
+     * Returns a validator that checks the internal state of the HasValue. This
+     * should be overridden for components with internal value conversion or
+     * validation, eg. when the user is providing a string that has to be parsed
+     * into a date. An invalid input from user will be exposed to
+     * a {@link Binder} and can be seen as a validation failure.
+     * 
+     * @since 8.1
+     * @return internal state validator
+     * @see Binder#validate()
+     */
+    public default Validator<V> getDefaultValidator() {
+        return Validator.alwaysPass();
+    }
 }
diff --git a/server/src/main/java/com/vaadin/ui/AbstractDateField.java b/server/src/main/java/com/vaadin/ui/AbstractDateField.java
index 0e738de253..0b1f60c0e4 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractDateField.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractDateField.java
@@ -38,6 +38,7 @@ import org.jsoup.nodes.Element;
 import com.googlecode.gentyref.GenericTypeReflector;
 import com.vaadin.data.Result;
 import com.vaadin.data.ValidationResult;
+import com.vaadin.data.Validator;
 import com.vaadin.data.ValueContext;
 import com.vaadin.data.validator.RangeValidator;
 import com.vaadin.event.FieldEvents.BlurEvent;
@@ -302,7 +303,10 @@ public abstract class AbstractDateField<T extends Temporal & TemporalAdjuster &
 
                     markAsDirty();
                 } else {
-                    parsedDate.ifOk(value -> setValue(value, true));
+                    parsedDate.ifOk(value -> {
+                        currentParseErrorMessage = null;
+                        setValue(value, true);
+                    });
 
                     /*
                      * Ensure the value is sent to the client if the value is
@@ -315,6 +319,7 @@ public abstract class AbstractDateField<T extends Temporal & TemporalAdjuster &
 
             } else if (newDate != oldDate
                     && (newDate == null || !newDate.equals(oldDate))) {
+                currentParseErrorMessage = null;
                 setValue(newDate, true); // Don't require a repaint, client
                 // updates itself
             } else if (!uiHasValidDateString) {
@@ -767,4 +772,17 @@ public abstract class AbstractDateField<T extends Temporal & TemporalAdjuster &
                 .collect(Collectors.toList());
     }
 
+    @Override
+    public Validator<T> getDefaultValidator() {
+        return new Validator<T>() {
+            @Override
+            public ValidationResult apply(T value, ValueContext context) {
+                if (currentParseErrorMessage != null) {
+                    return ValidationResult.error(currentParseErrorMessage);
+                }
+                // Pass to range validator.
+                return getRangeValidator().apply(value, context);
+            }
+        };
+    }
 }