Add example with export; rename methods

Author: psolomin

vertx-pg-client/src/main/java/examples/PgClientExamples.java

@@ -19,6 +19,8 @@
 
 import io.vertx.core.Future;
 import io.vertx.core.Vertx;
+import io.vertx.core.buffer.Buffer;
+import io.vertx.core.buffer.impl.BufferImpl;
 import io.vertx.core.json.JsonObject;
 import io.vertx.core.net.PemTrustOptions;
 import io.vertx.docgen.Source;
@@ -733,14 +735,26 @@ public void batchReturning(SqlClient client) {
       });
   }
 
-  public void copyFromStdinReturning(Vertx vertx, PgConnection client) {
-    client.copyFrom(
-      "COPY my_table FROM STDIN (FORMAT csv, HEADER)",
-      vertx.fileSystem().readFile("path/to/file")
-    ).execute().onSuccess(res -> {
-      Long rowsWritten = res.iterator().next().getLong("rowsWritten");
-      System.out.println("rows affected: " + rowsWritten);
-    });
+  public void importDataToDb(Vertx vertx, PgConnection client) {
+    vertx.fileSystem().readFile("path/to/file")
+      .flatMap(bufferAsyncResult -> {
+          return client.copyFrom(
+            "COPY my_table FROM STDIN (FORMAT csv, HEADER)",
+            bufferAsyncResult
+          ).execute();
+        }).onSuccess(result -> {
+          Long rowsWritten = result.iterator().next().getLong("rowsWritten");
+        System.out.println("rows written: " + rowsWritten);
+      });
+  }
+
+  public void exportDataFromDb(Vertx vertx, PgConnection client) {
+    Buffer buffer = new BufferImpl();
+    String path = "path/to/file";
+    client.copyTo("COPY my_table TO STDOUT (FORMAT csv, HEADER)", buffer)
+      .andThen(res -> {
+        vertx.fileSystem().writeFile("path/to/file.csv", buffer);
+      }).onSuccess(res -> System.out.println("Data exported to " + path));
   }
 
   public void pgBouncer(PgConnectOptions connectOptions) {

vertx-pg-client/src/main/java/io/vertx/pgclient/PgConnection.java

@@ -108,7 +108,7 @@ static Future<PgConnection> connect(Vertx vertx, String connectionUri) {
    * @param from byte stream data will be fetched from
    * @return result set with single field {@code rowsWritten}
    */
-  Query<RowSet<Row>> copyFrom(String sql, Future<Buffer> from);
+  Query<RowSet<Row>> copyFrom(String sql, Buffer from);
 
   /**
    * Exports data from a database with decoding.

vertx-pg-client/src/main/java/io/vertx/pgclient/impl/PgConnectionImpl.java

@@ -117,7 +117,7 @@ public PgConnection noticeHandler(Handler<PgNotice> handler) {
   }
 
   @Override
-  public Query<RowSet<Row>> copyFrom(String sql, Future<Buffer> from) {
+  public Query<RowSet<Row>> copyFrom(String sql, Buffer from) {
     return null;
   }
 

vertx-pg-client/src/test/java/io/vertx/pgclient/PgConnectionCopyTest.java

@@ -5,6 +5,12 @@
 import org.junit.Test;
 
 public class PgConnectionCopyTest extends PgConnectionTestBase {
+  public PgConnectionCopyTest() {
+    connector = (handler) -> PgConnection.connect(vertx, options).onComplete(ar -> {
+      handler.handle(ar.map(p -> p));
+    });
+  }
+
   @Test
   public void testCopyToRows(TestContext ctx) {
     Async async = ctx.async();