Add an optional HasValue to a ValueContext

5 files changed, 85 insertions, 4 deletions

diff --git a/documentation/components/components-fields.asciidoc b/documentation/components/components-fields.asciidoc
index 1415f98e73..77a308a3bb 100644
--- a/documentation/components/components-fields.asciidoc
+++ b/documentation/components/components-fields.asciidoc
@@ -170,7 +170,11 @@ class MyValidator implements Validator<String> {
 Since [interfacename]#Validator# is a functional
 interface, you can often simply write a lambda expression instead of a full class
 declaration. There is also an [methodname]#withValidator# overload that creates a
-validator from a boolean function and an error message.
+validator from a boolean function and an error message. If the application requires
+more sophisticated validation diagnostics (e.g. locale-specific), there is a
+method [methodname]#withValidator#, which uses a boolean function and an [classname]#ErrorMessageProvider#.
+The [classname]#ErrorMessageProvider# can compose diagnostic messages based on the locale of the validation
+and the source component value, which are provided with the [classname]#ValueContext#.
 
 [source, java]
 ----
diff --git a/server/src/main/java/com/vaadin/data/Binder.java b/server/src/main/java/com/vaadin/data/Binder.java
index c36029aa83..26720a3274 100644
--- a/server/src/main/java/com/vaadin/data/Binder.java
+++ b/server/src/main/java/com/vaadin/data/Binder.java
@@ -872,9 +872,9 @@ public class Binder<BEAN> implements Serializable {
          */
         protected ValueContext createValueContext() {
             if (field instanceof Component) {
-                return new ValueContext((Component) field);
+                return new ValueContext((Component) field, field);
             }
-            return new ValueContext(findLocale());
+            return new ValueContext(null, field, findLocale());
         }
 
         /**
diff --git a/server/src/main/java/com/vaadin/data/ValueContext.java b/server/src/main/java/com/vaadin/data/ValueContext.java
index 07857d34af..4ce1111ed0 100644
--- a/server/src/main/java/com/vaadin/data/ValueContext.java
+++ b/server/src/main/java/com/vaadin/data/ValueContext.java
@@ -33,6 +33,7 @@ import com.vaadin.ui.UI;
 public class ValueContext implements Serializable {
 
     private final Component component;
+    private final HasValue<?> hasValue;
     private final Locale locale;
 
     /**
@@ -40,6 +41,7 @@ public class ValueContext implements Serializable {
      */
     public ValueContext() {
         component = null;
+        hasValue = null;
         locale = findLocale();
     }
 
@@ -52,6 +54,7 @@ public class ValueContext implements Serializable {
     public ValueContext(Locale locale) {
         component = null;
         this.locale = locale;
+        hasValue = null;
     }
 
     /**
@@ -59,14 +62,54 @@ public class ValueContext implements Serializable {
      *
      * @param component
      *            The component related to current value. Can be null.
+     *            If the component implements {@link HasValue}, it will be returned by {@link #getHasValue()} as well.
      */
+    @SuppressWarnings("unchecked")
     public ValueContext(Component component) {
         Objects.requireNonNull(component,
                 "Component can't be null in ValueContext construction");
         this.component = component;
+        if(component instanceof HasValue) {
+            hasValue = (HasValue<?>) component;
+        } else {
+            hasValue = null;
+        }
+        locale = findLocale();
+    }
+
+    /**
+     * Constructor for {@code ValueContext}.
+     *
+     * @param component
+     *            The component related to current value. Can be null.
+     * @param hasValue
+     *            The value source related to current value. Can be null.
+     */
+    public ValueContext(Component component, HasValue<?> hasValue) {
+        Objects.requireNonNull(component,
+                "Component can't be null in ValueContext construction");
+        this.component = component;
+        this.hasValue = hasValue;
         locale = findLocale();
     }
 
+    /**
+     * Constructor for {@code ValueContext}.
+     *
+     * @param
+     *      component
+     *            The component can be {@code null}.
+     * @param locale
+     *            The locale used with conversion. Can be {@code null}.
+     * @param hasValue
+     *            The value source related to current value. Can be {@code null}.
+     */
+    public ValueContext(Component component, HasValue<?> hasValue, Locale locale) {
+        this.component = component;
+        this.hasValue = hasValue;
+        this.locale = locale;
+    }
+
     private Locale findLocale() {
         Locale l = null;
         if (component != null) {
@@ -100,4 +143,15 @@ public class ValueContext implements Serializable {
     public Optional<Locale> getLocale() {
         return Optional.ofNullable(locale);
     }
+
+    /**
+     * Returns an {@code Optional} for the {@code HasValue} used in the value
+     * conversion. In certain complicated cases, ex. cross-field validation, HasValue might be not available.
+     *
+     * @return the optional of {@code HasValue}
+     */
+    @SuppressWarnings("unused")
+    public Optional<HasValue<?>> getHasValue() {
+        return Optional.ofNullable(hasValue);
+    }
 }
diff --git a/server/src/main/java/com/vaadin/ui/AbstractDateField.java b/server/src/main/java/com/vaadin/ui/AbstractDateField.java
index 06e6d74c30..0e738de253 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractDateField.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractDateField.java
@@ -684,7 +684,7 @@ public abstract class AbstractDateField<T extends Temporal & TemporalAdjuster &
         } else {
             RangeValidator<T> validator = getRangeValidator();
             ValidationResult result = validator.apply(value,
-                    new ValueContext(this));
+                    new ValueContext(this, this));
             if (result.isError()) {
                 setComponentError(new UserError(getDateOutOfRangeMessage()));
             }
diff --git a/server/src/test/java/com/vaadin/data/ValueContextTest.java b/server/src/test/java/com/vaadin/data/ValueContextTest.java
index 2f13a71dbb..b96f7463cb 100644
--- a/server/src/test/java/com/vaadin/data/ValueContextTest.java
+++ b/server/src/test/java/com/vaadin/data/ValueContextTest.java
@@ -3,6 +3,7 @@ package com.vaadin.data;
 import java.util.Locale;
 import java.util.Objects;
 
+import com.vaadin.ui.CheckBox;
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
@@ -46,6 +47,28 @@ public class ValueContextTest extends UI {
                 Locale.getDefault(), locale);
     }
 
+    @Test
+    public void testHasValue1() {
+        setLocale(null);
+        ValueContext fromComponent = new ValueContext(textField);
+        Assert.assertEquals(textField, fromComponent.getHasValue().get());
+    }
+
+    @Test
+    public void testHasValue2() {
+        setLocale(null);
+        ValueContext fromComponent = new ValueContext(new CheckBox(), textField);
+        Assert.assertEquals(textField, fromComponent.getHasValue().get());
+    }
+
+    @Test
+    public void testHasValue3() {
+        setLocale(null);
+        ValueContext fromComponent = new ValueContext(new CheckBox(), textField, Locale.CANADA);
+        Assert.assertEquals(textField, fromComponent.getHasValue().get());
+        Assert.assertEquals(Locale.CANADA, fromComponent.getLocale().get());
+    }
+
     @Before
     public void setUp() {
         setLocale(UI_LOCALE);