added funtional operator for supporting case insensitive exact matchi… (

#201)

* added funtional operator for supporting case insensitive exact matching in mongo

* addressed

* update

document-store/src/integrationTest/java/org/hypertrace/core/documentstore/DocStoreQueryV1Test.java

@@ -86,6 +86,8 @@
 import org.hypertrace.core.documentstore.expression.impl.LogicalExpression;
 import org.hypertrace.core.documentstore.expression.impl.RelationalExpression;
 import org.hypertrace.core.documentstore.expression.impl.UnnestExpression;
+import org.hypertrace.core.documentstore.expression.operators.FunctionOperator;
+import org.hypertrace.core.documentstore.expression.operators.RelationalOperator;
 import org.hypertrace.core.documentstore.expression.type.FilterTypeExpression;
 import org.hypertrace.core.documentstore.model.options.UpdateOptions;
 import org.hypertrace.core.documentstore.model.subdoc.SubDocumentUpdate;
@@ -3362,6 +3364,37 @@ public void testMongoFunctionExpressionGroupBy(String dataStoreName) throws Exce
     testCountApi(dataStoreName, query, "query/function_expression_group_by_response.json");
   }
 
+  @ParameterizedTest
+  @ArgumentsSource(MongoProvider.class)
+  public void testToLowerCaseMongoFunctionOperator(String dataStoreName) throws Exception {
+    Collection collection = getCollection(dataStoreName);
+
+    List<SelectionSpec> selectionSpecs =
+        List.of(
+            SelectionSpec.of(IdentifierExpression.of("item")),
+            SelectionSpec.of(IdentifierExpression.of("price")),
+            SelectionSpec.of(IdentifierExpression.of("quantity")),
+            SelectionSpec.of(IdentifierExpression.of("date")));
+    Selection selection = Selection.builder().selectionSpecs(selectionSpecs).build();
+    Filter filter =
+        Filter.builder()
+            .expression(
+                RelationalExpression.of(
+                    FunctionExpression.builder()
+                        .operator(FunctionOperator.TO_LOWER_CASE)
+                        .operand(IdentifierExpression.of("item"))
+                        .build(),
+                    RelationalOperator.EQ,
+                    ConstantExpression.of("shampoo")))
+            .build();
+
+    Query query = Query.builder().setSelection(selection).setFilter(filter).build();
+
+    Iterator<Document> resultDocs = collection.find(query);
+    assertDocsAndSizeEqualWithoutOrder(
+        dataStoreName, resultDocs, "query/case_insensitive_exact_match_response.json", 2);
+  }
+
   private static Collection getCollection(final String dataStoreName) {
     return getCollection(dataStoreName, COLLECTION_NAME);
   }

document-store/src/integrationTest/resources/query/case_insensitive_exact_match_response.json

@@ -0,0 +1,14 @@
+[
+  {
+    "date": "2014-03-15T09:00:00Z",
+    "item": "Shampoo",
+    "price": 5,
+    "quantity": 10
+  },
+  {
+    "date": "2014-04-04T11:21:39.736Z",
+    "item": "Shampoo",
+    "price": 5,
+    "quantity": 20
+  }
+]

document-store/src/main/java/org/hypertrace/core/documentstore/expression/operators/FunctionOperator.java

@@ -2,6 +2,7 @@
 
 public enum FunctionOperator {
   // Unary operations
+  TO_LOWER_CASE,
   ABS,
   FLOOR,
   LENGTH, // This operator returns the length of an array

document-store/src/main/java/org/hypertrace/core/documentstore/mongo/query/parser/MongoFunctionExpressionParser.java

@@ -8,6 +8,7 @@
 import static org.hypertrace.core.documentstore.expression.operators.FunctionOperator.LENGTH;
 import static org.hypertrace.core.documentstore.expression.operators.FunctionOperator.MULTIPLY;
 import static org.hypertrace.core.documentstore.expression.operators.FunctionOperator.SUBTRACT;
+import static org.hypertrace.core.documentstore.expression.operators.FunctionOperator.TO_LOWER_CASE;
 import static org.hypertrace.core.documentstore.mongo.MongoUtils.getUnsupportedOperationException;
 
 import java.util.EnumMap;
@@ -32,6 +33,7 @@ public final class MongoFunctionExpressionParser extends MongoSelectTypeExpressi
               put(DIVIDE, "$divide");
               put(MULTIPLY, "$multiply");
               put(SUBTRACT, "$subtract");
+              put(TO_LOWER_CASE, "$toLower");
             }
           });