String <-> Enum converter which produces a human readable string (#14756)

Change-Id: I3a825f52a43daea3172ced23bc510118376e76cb

2 files changed, 99 insertions, 0 deletions

diff --git a/server/src/com/vaadin/data/util/converter/DefaultConverterFactory.java b/server/src/com/vaadin/data/util/converter/DefaultConverterFactory.java
index fdf858a528..26613c5d02 100644
--- a/server/src/com/vaadin/data/util/converter/DefaultConverterFactory.java
+++ b/server/src/com/vaadin/data/util/converter/DefaultConverterFactory.java
@@ -110,6 +110,8 @@ public class DefaultConverterFactory implements ConverterFactory {
             return new StringToBooleanConverter();
         } else if (Date.class.isAssignableFrom(sourceType)) {
             return new StringToDateConverter();
+        } else if (Enum.class.isAssignableFrom(sourceType)) {
+            return new StringToEnumConverter();
         } else {
             return null;
         }
diff --git a/server/src/com/vaadin/data/util/converter/StringToEnumConverter.java b/server/src/com/vaadin/data/util/converter/StringToEnumConverter.java
new file mode 100644
index 0000000000..a1328d831c
--- /dev/null
+++ b/server/src/com/vaadin/data/util/converter/StringToEnumConverter.java
@@ -0,0 +1,97 @@
+/*
+ * Copyright 2000-2014 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.data.util.converter;
+
+import java.util.EnumSet;
+import java.util.Locale;
+
+/**
+ * A converter that converts from {@link String} to an {@link Enum} and back.
+ * <p>
+ * Designed to provide nice human readable strings for {@link Enum} classes
+ * where the constants are named SOME_UPPERCASE_WORDS. Will not necessarily work
+ * correctly for other cases.
+ * </p>
+ * 
+ * @author Vaadin Ltd
+ * @since
+ */
+public class StringToEnumConverter implements Converter<String, Enum> {
+
+    @Override
+    public Enum convertToModel(String value, Class<? extends Enum> targetType,
+            Locale locale) throws ConversionException {
+        if (value == null) {
+            return null;
+        }
+        if (locale == null) {
+            locale = Locale.getDefault();
+        }
+
+        // Foo -> FOO
+        // Foo bar -> FOO_BAR
+        String result = value.replace(" ", "_").toUpperCase(locale);
+        try {
+            return Enum.valueOf(targetType, result);
+        } catch (IllegalArgumentException ee) {
+            // There was no match. Try to compare the available values to see if
+            // the constant is using something else than all upper case
+
+            EnumSet<?> set = EnumSet.allOf(targetType);
+            for (Enum e : set) {
+                if (e.name().toUpperCase(locale).equals(result)) {
+                    return e;
+                }
+            }
+
+            // Fallback did not work either, re-throw original exception so user
+            // knows what went wrong
+            throw new ConversionException(ee);
+        }
+    }
+
+    @Override
+    public String convertToPresentation(Enum value,
+            Class<? extends String> targetType, Locale locale)
+            throws ConversionException {
+        if (value == null) {
+            return null;
+        }
+        if (locale == null) {
+            locale = Locale.getDefault();
+        }
+
+        String enumString = value.toString();
+        // FOO -> Foo
+        // FOO_BAR -> Foo bar
+        // _FOO -> _foo
+        String result = enumString.substring(0, 1).toUpperCase(locale);
+        result += enumString.substring(1).toLowerCase(locale).replace('_', ' ');
+
+        return result;
+    }
+
+    @Override
+    public Class<Enum> getModelType() {
+        return Enum.class;
+    }
+
+    @Override
+    public Class<String> getPresentationType() {
+        return String.class;
+    }
+
+}