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https://issues.apache.org/jira/browse/NIFI-1280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15278358#comment-15278358
]
ASF GitHub Bot commented on NIFI-1280:
--------------------------------------
Github user markap14 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/420#discussion_r62701269
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/FilterCSVColumns.java
---
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.nifi.processors.standard;
+
+import static java.sql.Types.CHAR;
+import static java.sql.Types.LONGNVARCHAR;
+import static java.sql.Types.LONGVARCHAR;
+import static java.sql.Types.NCHAR;
+import static java.sql.Types.NVARCHAR;
+import static java.sql.Types.VARCHAR;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Properties;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.calcite.adapter.csv.CsvSchemaFactory2;
+import org.apache.calcite.jdbc.CalciteConnection;
+import org.apache.calcite.schema.Schema;
+import org.apache.calcite.schema.SchemaPlus;
+import org.apache.commons.lang3.StringEscapeUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.nifi.annotation.behavior.EventDriven;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+import org.apache.nifi.annotation.behavior.SideEffectFree;
+import org.apache.nifi.annotation.behavior.SupportsBatching;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.logging.ProcessorLog;
+import org.apache.nifi.processor.AbstractProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.ProcessorInitializationContext;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.io.StreamCallback;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.stream.io.BufferedInputStream;
+import org.apache.nifi.util.StopWatch;
+
+import com.google.common.collect.ImmutableMap;
+
+@EventDriven
+@SideEffectFree
+@SupportsBatching
+@Tags({"xml", "xslt", "transform"})
+@InputRequirement(Requirement.INPUT_REQUIRED)
+@CapabilityDescription("Filter out specific columns from CSV data. Some
other transformations are also supported."
+ + "Columns can be renamed, simple calculations performed,
aggregations, etc."
+ + "SQL select statement is used to specify how CSV data should be
transformed."
+ + "SQL statement follows standard SQL, some restrictions may
apply."
+ + "Successfully transformed CSV data is routed to the 'success'
relationship."
+ + "If transform fails, the original FlowFile is routed to the
'failure' relationship")
+public class FilterCSVColumns extends AbstractProcessor {
+
+ public static final PropertyDescriptor SQL_SELECT = new
PropertyDescriptor.Builder()
+ .name("SQL select statement")
+ .description("SQL select statement specifies how CSV data
should be transformed. "
+ + "Sql select should select from CSV.A table")
+ .required(true)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder()
+ .name("success")
+ .description("The FlowFile with transformed content will be
routed to this relationship")
+ .build();
+ public static final Relationship REL_FAILURE = new
Relationship.Builder()
+ .name("failure")
+ .description("If a FlowFile fails processing for any reason
(for example, the SQL statement contains columns not present in CSV), it will
be routed to this relationship")
+ .build();
+
+ private List<PropertyDescriptor> properties;
+ private Set<Relationship> relationships;
+
+ @Override
+ protected void init(final ProcessorInitializationContext context) {
+ final List<PropertyDescriptor> properties = new ArrayList<>();
+ properties.add(SQL_SELECT);
+ this.properties = Collections.unmodifiableList(properties);
+
+ final Set<Relationship> relationships = new HashSet<>();
+ relationships.add(REL_SUCCESS);
+ relationships.add(REL_FAILURE);
+ this.relationships = Collections.unmodifiableSet(relationships);
+ }
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ return relationships;
+ }
+
+ @Override
+ protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+ return properties;
+ }
+
+ @Override
+ public void onTrigger(final ProcessContext context, final
ProcessSession session) {
+ final FlowFile original = session.get();
+ if (original == null) {
+ return;
+ }
+
+ final ProcessorLog logger = getLogger();
+ final StopWatch stopWatch = new StopWatch(true);
+
+ try {
+ FlowFile transformed = session.write(original, new
StreamCallback() {
+ @Override
+ public void process(final InputStream rawIn, final
OutputStream out) throws IOException {
+ try (final InputStream in = new
BufferedInputStream(rawIn)) {
+
+ String sql =
context.getProperty(SQL_SELECT).getValue();
--- End diff --
It seems like SQL_SELECT should allow the Expression Language to be used. I
can certainly envision cases where the user will want to reference a FlowFile
Attribute.
> Create FilterCSVColumns Processor
> ---------------------------------
>
> Key: NIFI-1280
> URL: https://issues.apache.org/jira/browse/NIFI-1280
> Project: Apache NiFi
> Issue Type: Task
> Components: Extensions
> Reporter: Mark Payne
> Assignee: Toivo Adams
>
> We should have a Processor that allows users to easily filter out specific
> columns from CSV data. For instance, a user would configure two different
> properties: "Columns of Interest" (a comma-separated list of column indexes)
> and "Filtering Strategy" (Keep Only These Columns, Remove Only These Columns).
> We can do this today with ReplaceText, but it is far more difficult than it
> would be with this Processor, as the user has to use Regular Expressions,
> etc. with ReplaceText.
> Eventually a Custom UI could even be built that allows a user to upload a
> Sample CSV and choose which columns from there, similar to the way that Excel
> works when importing CSV by dragging and selecting the desired columns? That
> would certainly be a larger undertaking and would not need to be done for an
> initial implementation.
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