Add Issue21Test to reproduce the Problem in Issue #21. Adding a Note in the README.

Author: bytefish

JSqlServerBulkInsert/src/main/java/de/bytefish/jsqlserverbulkinsert/SqlServerBulkInsert.java

@@ -21,7 +21,6 @@ public class SqlServerBulkInsert<TEntity> implements ISqlServerBulkInsert<TEntit
 
     private final AbstractMapping<TEntity> mapping;
 
-
     public SqlServerBulkInsert(AbstractMapping<TEntity> mapping)
     {
         this.mapping = mapping;

JSqlServerBulkInsert/src/test/java/de/bytefish/jsqlserverbulkinsert/test/issues/Issue21Test.java

@@ -0,0 +1,102 @@
+package de.bytefish.jsqlserverbulkinsert.test.issues;
+
+import de.bytefish.jsqlserverbulkinsert.SqlServerBulkInsert;
+import de.bytefish.jsqlserverbulkinsert.mapping.AbstractMapping;
+import de.bytefish.jsqlserverbulkinsert.model.SchemaMetaData;
+import de.bytefish.jsqlserverbulkinsert.test.base.TransactionalTestBase;
+import de.bytefish.jsqlserverbulkinsert.test.mapping.UTCNanoTest;
+import de.bytefish.jsqlserverbulkinsert.test.model.Person;
+import de.bytefish.jsqlserverbulkinsert.test.utils.MeasurementUtils;
+import de.bytefish.jsqlserverbulkinsert.util.SchemaUtils;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.sql.*;
+import java.time.Clock;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.ZoneOffset;
+import java.time.temporal.ChronoUnit;
+import java.time.temporal.TemporalUnit;
+import java.util.*;
+
+/**
+ * https://github.com/JSqlServerBulkInsert/JSqlServerBulkInsert/issues/17
+ */
+public class Issue21Test extends TransactionalTestBase {
+
+    public class Issue21Entity {
+
+        public LocalDateTime lastUpdate;
+
+        public Issue21Entity(LocalDateTime lastUpdate) {
+            this.lastUpdate = lastUpdate;
+        }
+
+        public LocalDateTime getLastUpdate() {
+            return lastUpdate;
+        }
+    }
+
+    public class Issue21EntityMapping extends AbstractMapping<Issue21Entity> {
+
+        public Issue21EntityMapping() {
+            super("dbo", "UnitTest");
+
+            mapLocalDateTime("LastUpdated", x -> x.getLastUpdate().truncatedTo(ChronoUnit.MILLIS));
+        }
+    }
+
+    @Override
+    protected void onSetUpInTransaction() throws Exception {
+        createTestTable();
+    }
+
+    @Test
+    public void bulkInsertToDateTimeColumn() throws SQLException {
+
+        // Expected LocalDate 2017-05-15T12:09:07.161013600
+        LocalDateTime current = LocalDateTime.now(Clock.systemUTC());
+
+        // Create entities
+        List<Issue21Entity> entities = Arrays.asList(new Issue21Entity (current));
+        // Create the BulkInserter:
+        Issue21EntityMapping mapping = new Issue21EntityMapping();
+        // Now save all entities of a given stream:
+        new SqlServerBulkInsert<>(mapping).saveAll(connection, entities.stream());
+
+        // And assert all have been written to the database:
+        ResultSet rs = getAll();
+        while (rs.next()) {
+            // for debugging purposes, can look at how the dates are stored in the DB
+            String dbDate = rs.getString("lastUpdated");
+            // Get the Date we have written:
+            LocalDateTime date = rs.getObject("lastUpdated", LocalDateTime.class);
+
+            // We should have a date:
+            Assert.assertNotNull(date);
+
+            Assert.assertEquals(current.truncatedTo(ChronoUnit.SECONDS), date.truncatedTo(ChronoUnit.SECONDS));
+        }
+    }
+
+    private ResultSet getAll() throws SQLException {
+
+        String sqlStatement = "SELECT * FROM dbo.UnitTest";
+
+        Statement statement = connection.createStatement();
+
+        return statement.executeQuery(sqlStatement);
+    }
+
+    private void createTestTable() throws SQLException {
+        String sqlStatement = "CREATE TABLE [dbo].[UnitTest]\n" +
+                "            (\n" +
+                "                lastUpdated datetime" +
+                "            );";
+
+        Statement statement = connection.createStatement();
+
+        statement.execute(sqlStatement);
+    }
+}

README.md

@@ -111,6 +111,23 @@ private class MySampleEntityMapping extends AbstractMapping<MySampleEntity> {
 }
 ```
 
+### Notes on DATETIME Columns ###
+
+If you are trying to map a `LocalDateTime` to a `DATETIME` column, you need to drop the nanoseconds part. A SQL Server `DATETIME` column doesn't have this level of precision.
+
+It can be fixed by using `LocalDateTime#truncatedTo(ChronoUnit.MILLIS`, like this:
+
+```java
+public class Issue21EntityMapping extends AbstractMapping<Issue21Entity> {
+
+    public Issue21EntityMapping() {
+        super("dbo", "UnitTest");
+
+        mapLocalDateTime("LastUpdated", x -> x.getLastUpdate().truncatedTo(ChronoUnit.MILLIS));
+    }
+}
+```
+
 ### Order of Columns ###
 
 The ``SqlServerBulkCopy`` implementation of the Microsoft JDBC driver requires, that the destination schema and