feat(GH-204): added LOWER predicate for case insensitive match

graphql-jpa-query-schema/src/main/java/com/introproventures/graphql/jpa/query/schema/impl/GraphQLJpaSchemaBuilder.java

@@ -515,6 +515,12 @@ private GraphQLInputType getWhereAttributeType(Attribute<?,?> attribute) {
                         .type(getAttributeInputType(attribute))
                         .build()
                     )
+                    .field(GraphQLInputObjectField.newInputObjectField()
+                           .name(Criteria.LOWER.name())
+                           .description("Case insensitive match criteria")
+                           .type(getAttributeInputType(attribute))
+                           .build()
+                    )
                     .field(GraphQLInputObjectField.newInputObjectField()
                         .name(Criteria.CASE.name())
                         .description("Case sensitive match criteria")

graphql-jpa-query-schema/src/main/java/com/introproventures/graphql/jpa/query/schema/impl/JpaPredicateBuilder.java

@@ -129,7 +129,7 @@ protected Predicate getStringPredicate(Path<String> root, PredicateFilter filter
         if(arrayValuePredicate == null) {
             String compareValue = filter.getValue().toString();
             Expression<String> fieldValue = root;
-
+            
             if (filter.getCriterias().contains(PredicateFilter.Criteria.IN)) {
                 CriteriaBuilder.In<Object> in = cb.in(root);
                 return in.value(compareValue);
@@ -141,6 +141,10 @@ protected Predicate getStringPredicate(Path<String> root, PredicateFilter filter
             if (filter.getCriterias().contains(PredicateFilter.Criteria.EQ)) {
                 return cb.equal(fieldValue, compareValue);
             } 
+            else if (filter.getCriterias().contains(PredicateFilter.Criteria.LOWER)) {
+                return cb.equal(cb.lower(fieldValue), 
+                                compareValue.toLowerCase());
+            }
             else if (filter.getCriterias().contains(PredicateFilter.Criteria.NE)) {
                 return cb.notEqual(fieldValue, compareValue);
             }

graphql-jpa-query-schema/src/main/java/com/introproventures/graphql/jpa/query/schema/impl/PredicateFilter.java

@@ -60,10 +60,13 @@ public enum Criteria {
          * case sensitive (strings)
          */
         CASE,
+        /**
+         * case insensitive match
+         * <pre>LOWER(field) = LOWER(SEARCH)</pre> 
+         */
+        LOWER,
         /**
          * end of the string matches
-         * <pre>LOWER(field) LIKE LOWER(SEARCH)</pre> if not set then case
-         * insensitive match
          */
         ENDS,
         /**

graphql-jpa-query-schema/src/test/java/com/introproventures/graphql/jpa/query/schema/GraphQLExecutorTests.java

@@ -1550,6 +1550,38 @@ public void queryWithEQMatchingCase() {
         assertThat(result.toString()).isEqualTo(expected);
     }
 
+    @Test
+    public void queryWithLOWERNotMatchingCase() {
+        //given:
+        String query = "query { Books ( where: { title: {LOWER: \"WAR AND PEACE\"}}) { select { id title} } }";
+
+        String expected = "{Books={select=[" +
+                "{id=2, title=War and Peace}" +
+                "]}}";
+
+        //when:
+        Object result = executor.execute(query).getData();
+
+        //then:
+        assertThat(result.toString()).isEqualTo(expected);
+    }
+
+    @Test
+    public void queryWithLOWERMatchingCase() {
+        //given:
+        String query = "query { Books ( where: { title: {LOWER: \"War and Peace\"}}) { select { id title} } }";
+
+        String expected = "{Books={select=[" +
+                "{id=2, title=War and Peace}" +
+                "]}}";
+
+        //when:
+        Object result = executor.execute(query).getData();
+
+        //then:
+        assertThat(result.toString()).isEqualTo(expected);
+    }    
+
     @Test
     public void shouldNotReturnStaleCacheResultsFromPreviousQueryForCollectionCriteriaExpression() {
         //given: