Added transformation to copy the schema name to the topic. Fixes #48. (#49)

Author: jcustenborder

src/main/java/com/github/jcustenborder/kafka/connect/transform/common/SchemaNameToTopic.java

@@ -0,0 +1,85 @@
+/**
+ * Copyright © 2019 Jeremy Custenborder (jcustenborder@gmail.com)
+ *
+ * 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.github.jcustenborder.kafka.connect.transform.common;
+
+import com.github.jcustenborder.kafka.connect.utils.config.Description;
+import com.github.jcustenborder.kafka.connect.utils.config.Title;
+import org.apache.kafka.common.config.ConfigDef;
+import org.apache.kafka.connect.connector.ConnectRecord;
+import org.apache.kafka.connect.transforms.Transformation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Map;
+
+@Title("SchemaNameToTopic")
+@Description("This transformation is used to take the name from the schema for the key or value and" +
+    " replace the topic with this value.")
+public abstract class SchemaNameToTopic<R extends ConnectRecord<R>> implements Transformation<R> {
+  private static final Logger log = LoggerFactory.getLogger(SchemaNameToTopic.class);
+
+  @Override
+  public ConfigDef config() {
+    return new ConfigDef();
+  }
+
+  @Override
+  public void close() {
+
+  }
+
+  @Override
+  public void configure(Map<String, ?> map) {
+
+  }
+
+  public static class Key<R extends ConnectRecord<R>> extends SchemaNameToTopic<R> {
+    @Override
+    public R apply(R r) {
+
+      return r.newRecord(
+          r.keySchema().name(),
+          r.kafkaPartition(),
+          r.keySchema(),
+          r.key(),
+          r.valueSchema(),
+          r.value(),
+          r.timestamp(),
+          r.headers()
+      );
+    }
+  }
+
+
+  public static class Value<R extends ConnectRecord<R>> extends SchemaNameToTopic<R> {
+    @Override
+    public R apply(R r) {
+
+      return r.newRecord(
+          r.valueSchema().name(),
+          r.kafkaPartition(),
+          r.keySchema(),
+          r.key(),
+          r.valueSchema(),
+          r.value(),
+          r.timestamp(),
+          r.headers()
+      );
+    }
+  }
+
+
+}

src/test/java/com/github/jcustenborder/kafka/connect/transform/common/SchemaNameToTopicTest.java

@@ -0,0 +1,64 @@
+package com.github.jcustenborder.kafka.connect.transform.common;
+
+import com.google.common.base.Strings;
+import org.apache.kafka.connect.data.Field;
+import org.apache.kafka.connect.data.Schema;
+import org.apache.kafka.connect.data.SchemaBuilder;
+import org.apache.kafka.connect.data.Struct;
+import org.apache.kafka.connect.sink.SinkRecord;
+import org.apache.kafka.connect.transforms.Transformation;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+public class SchemaNameToTopicTest {
+  Transformation<SinkRecord> transformation  = new SchemaNameToTopic.Value<>();
+  SinkRecord exampleRecord(Schema schema) {
+    Struct struct = new Struct(schema);
+    for (Field field : schema.fields()) {
+      struct.put(field, Strings.repeat("x", 50));
+    }
+    return new SinkRecord(
+        "test",
+        0,
+        null,
+        null,
+        schema,
+        struct,
+        1234L
+    );
+
+  }
+
+  Schema exampleSchema(List<String> fieldNames, final int version) {
+    SchemaBuilder builder = SchemaBuilder.struct()
+        .name(this.getClass().getName());
+    for (String fieldName : fieldNames) {
+      builder.field(fieldName, Schema.STRING_SCHEMA);
+    }
+    builder.version(version);
+    return builder.build();
+  }
+
+  @Test
+  public void apply() {
+    Schema schema = SchemaBuilder.struct()
+        .name("com.foo.bar.whatever.ASDF")
+        .field("firstName", Schema.OPTIONAL_STRING_SCHEMA)
+        .build();
+    SinkRecord input = exampleRecord(schema);
+    SinkRecord actual = this.transformation.apply(input);
+    assertNotNull(actual);
+    assertEquals(schema.name(), actual.topic());
+
+
+  }
+
+
+}