Implement date expressions

driver-core/src/main/com/mongodb/client/model/expressions/DateExpression.java

@@ -20,5 +20,18 @@
  * Expresses a date value.
  */
 public interface DateExpression extends Expression {
+    IntegerExpression year(StringExpression timezone);
+    IntegerExpression month(StringExpression timezone);
+    IntegerExpression dayOfMonth(StringExpression timezone);
+    IntegerExpression dayOfWeek(StringExpression timezone);
+    IntegerExpression dayOfYear(StringExpression timezone);
+    IntegerExpression hour(StringExpression timezone);
+    IntegerExpression minute(StringExpression timezone);
+    IntegerExpression second(StringExpression timezone);
+    IntegerExpression week(StringExpression timezone);
+    IntegerExpression millisecond(StringExpression timezone);
+
+    StringExpression dateToString();
+    StringExpression dateToString(StringExpression timezone, StringExpression format);
 
 }

driver-core/src/main/com/mongodb/client/model/expressions/Expressions.java

@@ -33,9 +33,7 @@
 
 import java.time.Instant;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
-import java.util.stream.Collectors;
 
 import static com.mongodb.client.model.expressions.MqlExpression.AstPlaceholder;
 

driver-core/src/main/com/mongodb/client/model/expressions/MqlExpression.java

@@ -332,6 +332,77 @@ public IntegerExpression min(final IntegerExpression i) {
         return new MqlExpression<>(ast("$min", i));
     }
 
+    /** @see DateExpression */
+
+    private MqlExpression<Expression> usingTimezone(final String name, final StringExpression timezone) {
+        return new MqlExpression<>((cr) -> astDoc(name, new BsonDocument()
+                .append("date", this.toBsonValue(cr))
+                .append("timezone", extractBsonValue(cr, timezone))));
+    }
+
+    @Override
+    public IntegerExpression year(final StringExpression timezone) {
+        return usingTimezone("$year", timezone);
+    }
+
+    @Override
+    public IntegerExpression month(final StringExpression timezone) {
+        return usingTimezone("$month", timezone);
+    }
+
+    @Override
+    public IntegerExpression dayOfMonth(final StringExpression timezone) {
+        return usingTimezone("$dayOfMonth", timezone);
+    }
+
+    @Override
+    public IntegerExpression dayOfWeek(final StringExpression timezone) {
+        return usingTimezone("$dayOfWeek", timezone);
+    }
+
+    @Override
+    public IntegerExpression dayOfYear(final StringExpression timezone) {
+        return usingTimezone("$dayOfYear", timezone);
+    }
+
+    @Override
+    public IntegerExpression hour(final StringExpression timezone) {
+        return usingTimezone("$hour", timezone);
+    }
+
+    @Override
+    public IntegerExpression minute(final StringExpression timezone) {
+        return usingTimezone("$minute", timezone);
+    }
+
+    @Override
+    public IntegerExpression second(final StringExpression timezone) {
+        return usingTimezone("$second", timezone);
+    }
+
+    @Override
+    public IntegerExpression week(final StringExpression timezone) {
+        return usingTimezone("$week", timezone);
+    }
+
+    @Override
+    public IntegerExpression millisecond(final StringExpression timezone) {
+        return usingTimezone("$millisecond", timezone);
+    }
+
+    @Override
+    public StringExpression dateToString() {
+        return newMqlExpression((cr) -> astDoc("$dateToString", new BsonDocument()
+                .append("date", this.toBsonValue(cr))));
+    }
+
+    @Override
+    public StringExpression dateToString(final StringExpression timezone, final StringExpression format) {
+        return newMqlExpression((cr) -> astDoc("$dateToString", new BsonDocument()
+                .append("date", this.toBsonValue(cr))
+                .append("format", extractBsonValue(cr, format))
+                .append("timezone", extractBsonValue(cr, timezone))));
+    }
 
     /** @see StringExpression */
 

driver-core/src/test/functional/com/mongodb/client/model/expressions/DateExpressionsFunctionalTest.java

@@ -0,0 +1,157 @@
+/*
+ * Copyright 2008-present MongoDB, Inc.
+ *
+ * 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.mongodb.client.model.expressions;
+
+import org.junit.jupiter.api.Test;
+
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.time.temporal.ChronoField;
+
+import static com.mongodb.client.model.expressions.Expressions.of;
+import static java.time.format.DateTimeFormatter.ISO_LOCAL_DATE_TIME;
+
+class DateExpressionsFunctionalTest extends AbstractExpressionsFunctionalTest {
+    // https://www.mongodb.com/docs/manual/reference/operator/aggregation/#date-expression-operators
+
+    private final Instant instant = Instant.parse("2007-12-03T10:15:30.005Z");
+    private final DateExpression date = of(instant);
+    private final ZonedDateTime utcDateTime = ZonedDateTime.ofInstant(instant, ZoneId.of(ZoneOffset.UTC.getId()));
+    private final StringExpression utc = of("UTC");
+
+    @Test
+    public void literalsTest() {
+        assertExpression(
+                instant,
+                date,
+                "{'$date': '2007-12-03T10:15:30.005Z'}");
+    }
+
+    @Test
+    public void yearTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/year/
+        assertExpression(
+                utcDateTime.get(ChronoField.YEAR),
+                date.year(utc),
+                "{'$year': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void monthTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/month/
+        assertExpression(
+                utcDateTime.get(ChronoField.MONTH_OF_YEAR),
+                date.month(utc),
+                "{'$month': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void dayOfMonthTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/dayOfMonth/
+        assertExpression(
+                utcDateTime.get(ChronoField.DAY_OF_MONTH),
+                date.dayOfMonth(utc),
+                "{'$dayOfMonth': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void dayOfWeekTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/dayOfWeek/
+        assertExpression(
+                utcDateTime.get(ChronoField.DAY_OF_WEEK) + 1,
+                date.dayOfWeek(utc),
+                "{'$dayOfWeek': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void dayOfYearTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/dayOfYear/
+        assertExpression(
+                utcDateTime.get(ChronoField.DAY_OF_YEAR),
+                date.dayOfYear(utc),
+                "{'$dayOfYear': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void hourTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/hour/
+        assertExpression(
+                utcDateTime.get(ChronoField.HOUR_OF_DAY),
+                date.hour(utc),
+                "{'$hour': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void minuteTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/minute/
+        assertExpression(
+                utcDateTime.get(ChronoField.MINUTE_OF_HOUR),
+                date.minute(utc),
+                "{'$minute': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void secondTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/second/
+        assertExpression(
+                utcDateTime.get(ChronoField.SECOND_OF_MINUTE),
+                date.second(utc),
+                "{'$second': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void weekTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/week/
+        assertExpression(
+                48,
+                date.week(utc),
+                "{'$week': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void millisecondTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/millisecond/
+        assertExpression(
+                utcDateTime.get(ChronoField.MILLI_OF_SECOND),
+                date.millisecond(utc),
+                "{'$millisecond': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, 'timezone': 'UTC'}}");
+    }
+
+    @Test
+    public void dateToStringTest() {
+        // https://www.mongodb.com/docs/manual/reference/operator/aggregation/dateToString/
+        assertExpression(
+                instant.toString(),
+                date.dateToString(),
+                "{'$dateToString': {'date': {'$date': '2007-12-03T10:15:30.005Z'}}}");
+        // with parameters
+        assertExpression(
+                utcDateTime.withZoneSameInstant(ZoneId.of("America/New_York")).format(ISO_LOCAL_DATE_TIME),
+                date.dateToString(of("America/New_York"), of("%Y-%m-%dT%H:%M:%S.%L")),
+                "{'$dateToString': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, "
+                        + "'format': '%Y-%m-%dT%H:%M:%S.%L', "
+                        + "'timezone': 'America/New_York'}}");
+        assertExpression(
+                utcDateTime.withZoneSameInstant(ZoneId.of("+04:30")).format(ISO_LOCAL_DATE_TIME),
+                date.dateToString(of("+04:30"), of("%Y-%m-%dT%H:%M:%S.%L")),
+                "{'$dateToString': {'date': {'$date': '2007-12-03T10:15:30.005Z'}, "
+                        + "'format': '%Y-%m-%dT%H:%M:%S.%L', "
+                        + "'timezone': '+04:30'}}");
+    }
+}