Fix issue with using Null as DateType (#1544)

* Fix issue with using Null as DateType
* Added logic for parsing date-formatted (yyyy-MM-dd) strings into sql Date values.

src/main/java/net/snowflake/client/core/arrow/VarCharConverter.java

@@ -5,6 +5,11 @@
 
 import java.math.BigDecimal;
 import java.nio.charset.StandardCharsets;
+import java.sql.Date;
+import java.text.DateFormat;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.TimeZone;
 import net.snowflake.client.core.DataConversionContext;
 import net.snowflake.client.core.SFException;
 import net.snowflake.client.jdbc.ErrorCode;
@@ -143,4 +148,19 @@ public boolean toBoolean(int index) throws SFException {
           SnowflakeUtil.BOOLEAN_STR, str);
     }
   }
+
+  @Override
+  public Date toDate(int index, TimeZone jvmTz, boolean useDateFormat) throws SFException {
+    if (isNull(index)) {
+      return null;
+    }
+    try {
+      DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
+      Date date = new Date(dateFormat.parse(toString(index)).getTime());
+      return date;
+    } catch (ParseException e) {
+      throw new SFException(
+          ErrorCode.INVALID_VALUE_CONVERT, logicalTypeStr, SnowflakeUtil.DATE_STR, "");
+    }
+  }
 }

src/test/java/net/snowflake/client/core/arrow/VarCharConverterTest.java

@@ -10,13 +10,8 @@
 import static org.junit.Assert.assertTrue;
 
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Random;
-import java.util.Set;
+import java.sql.Date;
+import java.util.*;
 import net.snowflake.client.TestUtil;
 import net.snowflake.client.core.SFException;
 import org.apache.arrow.memory.BufferAllocator;
@@ -107,4 +102,28 @@ public void testGetBoolean() throws SFException {
 
     vector.close();
   }
+
+  @Test
+  public void testGetDate() throws SFException {
+    Map<String, String> customFieldMeta = new HashMap<>();
+    customFieldMeta.put("logicalType", "FIXED");
+
+    FieldType fieldType =
+        new FieldType(true, Types.MinorType.VARCHAR.getType(), null, customFieldMeta);
+
+    VarCharVector vector = new VarCharVector("col_one", fieldType, allocator);
+    vector.setNull(0);
+    vector.setSafe(1, "2023-10-26".getBytes(StandardCharsets.UTF_8));
+    vector.setSafe(2, "abc".getBytes(StandardCharsets.UTF_8));
+
+    ArrowVectorConverter converter = new VarCharConverter(vector, 0, this);
+    Date expectedDate = new Date(123, 9, 26);
+    Date actualDate = converter.toDate(1, TimeZone.getDefault(), false);
+
+    assertThat(null, is(converter.toDate(0, null, false)));
+    assertThat(actualDate, is(expectedDate));
+    TestUtil.assertSFException(invalidConversionErrorCode, () -> converter.toDate(2, null, false));
+
+    vector.close();
+  }
 }