Bug 37205327 - [37167822->24.09.1] CollectionExtractor - fix fromCollection methods (merge ce/main -> ce/24.09 @ 112106)

[git-p4: depot-paths = "//dev/coherence-ce/release/coherence-ce-v24.09/": change = 112110]

Author: ghillert

prj/coherence-core/src/main/java/com/tangosol/util/Extractors.java

@@ -250,56 +250,45 @@ public static <T, E> ValueExtractor<T, E> identityCast()
         }
 
     /**
-     * Returns a {@link CollectionExtractor} that extracts the specified fields
-     * where extraction occurs in a chain where the result of each
-     * field extraction is the input to the next extractor. The result
-     * returned is the result of the final extractor in the chain.
+     * Returns a {@link CollectionExtractor} that extracts the specified field.
      *
-     * @param fields  the field names to extract (if any field name contains a dot '.'
-     *                that field name is split into multiple field names delimiting on
-     *                the dots.
+     * @param from  the field name to extract the value from
      *
      * @param <T> the type of the object to extract from
      * @param <E> the type of the extracted value
      *
-     * @return a {@link CollectionExtractor} that extracts the value(s) of the specified field(s)
+     * @return a {@link CollectionExtractor} that extracts the value(s) of the specified field
      *
-     * @throws IllegalArgumentException if the fields parameter is {@code null} or an
-     *         empty array
+     * @throws IllegalArgumentException if the fields parameter is {@code null} or empty
      *
      * @see CollectionExtractor
-     * @see ChainedExtractor
      */
-    public static <T, E> CollectionExtractor<T, E> fromCollection(String... fields)
+    public static <T, E> CollectionExtractor<T, E> fromCollection(String from)
         {
-        return new CollectionExtractor(chained(fields));
+        if (Objects.requireNonNull(from).isBlank())
+            {
+            throw new IllegalArgumentException("The fromCollection parameter cannot be empty");
+            }
+        return new CollectionExtractor<>(extract(from));
         }
 
     /**
-     * Returns a {@link CollectionExtractor} that wraps the specified {@link ValueExtractor}s.
-     * <p>
-     * If the {@code extractors} parameter is a single {@link ValueExtractor} then a
-     * {@link CollectionExtractor} is returned wrapping that extractor. If the {@code extractors} is
-     * multiple {@link ValueExtractor} instances in a chain, a {@link CollectionExtractor} is returned
-     * that wraps a {@link ChainedExtractor} that wraps the chain of {@link ValueExtractor}
-     * instances
+     * Returns a {@link CollectionExtractor} that wraps the specified {@link ValueExtractor}.
      *
-     * @param extractors  the chain of {@link ValueExtractor}s to use to extract the value
+     * @param extractor   the {@link ValueExtractor} to use to extract the value
      * @param <T>         the type of the object to extract from
      * @param <E>         the type of the extracted value
      *
-     * @return a {@link CollectionExtractor} that extracts the value(s) of the specified field(s)
+     * @return a {@link CollectionExtractor} that extracts the value(s) of the specified field
      *
-     * @throws IllegalArgumentException if the fields parameter is {@code null} or an
-     *         empty array
+     * @throws IllegalArgumentException if the fields parameter is {@code null}
      *
      * @see CollectionExtractor
-     * @see ChainedExtractor
      *
      */
-    public static <T, E> CollectionExtractor<T, E> fromCollection(ValueExtractor<?, ?>... extractors)
+    public static <T, E> CollectionExtractor<T, E> fromCollection(ValueExtractor<T, E> extractor)
         {
-        return new CollectionExtractor(chained(extractors));
+        return new CollectionExtractor<>(extractor);
         }
 
     /**

prj/test/functional/extractor/src/main/java/extractor/ExtractorTests.java

@@ -48,6 +48,7 @@
 import java.io.IOException;
 
 import java.util.Calendar;
+import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 
@@ -126,38 +127,11 @@ public void testReflection()
     public void testCollection()
         {
         NamedCache cache = getNamedCache();
-
-        Country usa = new Country("USA");
-        usa.setArea(3_796_742);
-        usa.setPopulation(334_914_895);
-        usa.addCity(new City("New York", 8_258_035))
-           .addCity(new City("Los Angeles", 3_820_914))
-           .addCity(new City("Chicago", 2_664_452));
-
-        Country germany = new Country("Germany");
-        germany.setArea(357_569);
-        germany.setPopulation(82_719_540);
-        germany.addCity(new City("Berlin", 3_677_472))
-               .addCity(new City("Hamburg", 1_906_411))
-               .addCity(new City("Munich", 1_487_708));
-
-        Country taiwan = new Country("Taiwan");
-        taiwan.setArea(36_197);
-        taiwan.setPopulation(23_894_394);
-        taiwan.addCity(new City("New Taipei", 3_974_911))
-              .addCity(new City("Kaohsiung", 2_778_992))
-              .addCity(new City("Taichung", 2_759_887))
-              .addCity(new City("Taipei", 2_696_316));
-
-        cache.put("us", usa);
-        cache.put("de", germany);
-        cache.put("tw", taiwan);
-
-        cache.values(Filters.in(Extractors.extract("name"), Set.of("USA", "Germany"))).size();
+        addTestCountriesToCache(cache);
 
         ValueExtractor<Country, String> countryNameExtractor = Extractors.extract("name");
 
-        Filter countryFilter = Filters.in(Extractors.extract("name"), "USA", "Germany");
+        Filter countryFilter = Filters.in(countryNameExtractor, "USA", "Germany");
 
         ValueExtractor<Country, List<City>> listOfCitiesExtractor = Extractors.extract("cities");
         ValueExtractor<City, String> cityNameExtractor = Extractors.extract("name");
@@ -178,6 +152,35 @@ public void testCollection()
         cache.destroy();
         }
 
+    /**
+     * Test for {@link CollectionExtractor}.
+     */
+    @Test
+    public void testCollectionInTypesafeManner()
+        {
+        NamedCache cache = getNamedCache();
+        addTestCountriesToCache(cache);
+
+        ValueExtractor<Country, String> countryNameExtractor = ValueExtractor.of(Country::getName);
+
+        Filter countryFilter = Filters.in(countryNameExtractor, "USA", "Germany");
+
+        ValueExtractor<Country, Collection<String>> listOfCityNamesExtractor = ValueExtractor.of(Country::getCities)
+                .andThen(Extractors.fromCollection(City::getName));
+
+        List<List<String>> listCityNames = cache.stream(countryFilter, listOfCityNamesExtractor).toList();
+
+        assertEquals("Expected 2 results (Countries) but got " + listCityNames.size(), 2, listCityNames.size());
+
+        List<String> listJustCities = listCityNames.stream().flatMap(list -> list.stream()).toList();
+
+        assertEquals("Expected 6 cities but got " + listJustCities.size(), 6, listJustCities.size());
+
+        assertThat(listJustCities, hasItems("Berlin", "Hamburg", "Munich", "Los Angeles", "New York", "Chicago"));
+
+        cache.destroy();
+        }
+
     /**
      * Test for {@link DeserializationAccelerator}.
      */
@@ -444,6 +447,35 @@ public void writeExternal(PofWriter out)
         protected static final AtomicInteger f_deserializationCount = new AtomicInteger();
         }
 
+    private void addTestCountriesToCache(NamedCache cache)
+        {
+        Country usa = new Country("USA");
+        usa.setArea(3_796_742);
+        usa.setPopulation(334_914_895);
+        usa.addCity(new City("New York", 8_258_035))
+                .addCity(new City("Los Angeles", 3_820_914))
+                .addCity(new City("Chicago", 2_664_452));
+
+        Country germany = new Country("Germany");
+        germany.setArea(357_569);
+        germany.setPopulation(82_719_540);
+        germany.addCity(new City("Berlin", 3_677_472))
+                .addCity(new City("Hamburg", 1_906_411))
+                .addCity(new City("Munich", 1_487_708));
+
+        Country taiwan = new Country("Taiwan");
+        taiwan.setArea(36_197);
+        taiwan.setPopulation(23_894_394);
+        taiwan.addCity(new City("New Taipei", 3_974_911))
+                .addCity(new City("Kaohsiung", 2_778_992))
+                .addCity(new City("Taichung", 2_759_887))
+                .addCity(new City("Taipei", 2_696_316));
+
+        cache.put("us", usa);
+        cache.put("de", germany);
+        cache.put("tw", taiwan);
+        }
+
     // ----- inner class: CountingExtractor ---------------------------------
 
     public static class CountingExtractor

prj/test/unit/coherence-tests/src/test/java/com/tangosol/util/extractor/CollectionExtractorTest.java

@@ -87,7 +87,7 @@ public void testUseExtractorsFromCollectionWithStringArguments()
     @Test(expected = IllegalArgumentException.class)
     public void testUseExtractorsFromCollectionWithEmptyStringParams()
         {
-        Extractors.fromCollection(new String[]{});
+        Extractors.fromCollection("");
         }
 
     @Test
@@ -108,7 +108,7 @@ public void testUseExtractorsFromCollection()
     @Test(expected = IllegalArgumentException.class)
     public void testUseExtractorsFromCollectionWithEmptyParams()
         {
-        Extractors.fromCollection(new UniversalExtractor[]{});
+        Extractors.fromCollection((ValueExtractor) null);
         }
     }