Github user markap14 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/158#discussion_r50575812
--- Diff:
nifi-nar-bundles/nifi-kite-bundle/nifi-kite-processors/src/main/java/org/apache/nifi/processors/kite/InferAvroSchema.java
---
@@ -0,0 +1,454 @@
+/*
+ * 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.kite;
+
+import org.apache.avro.Schema;
+import org.apache.commons.io.IOUtils;
+import org.apache.commons.lang.StringUtils;
+import org.apache.nifi.annotation.behavior.*;
+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.flowfile.attributes.CoreAttributes;
+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.InputStreamCallback;
+import org.apache.nifi.processor.io.OutputStreamCallback;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.kitesdk.data.spi.JsonUtil;
+import org.kitesdk.data.spi.filesystem.CSVProperties;
+import org.kitesdk.data.spi.filesystem.CSVUtil;
+import org.kitesdk.shaded.com.google.common.collect.ImmutableSet;
+import org.omg.CORBA.OBJ_ADAPTER;
+
+
+import java.io.*;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Set;
+import java.util.HashSet;
+import java.util.Collections;
+import java.util.concurrent.atomic.AtomicReference;
+
+@Tags({"kite", "avro", "infer", "schema", "csv", "json"})
+@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
+@CapabilityDescription("Examines the contents of the incoming FlowFile to
infer an Avro schema. The processor will" +
+ " use the Kite SDK to make an attempt to automatically generate an
Avro schema from the incoming content." +
+ " When inferring the schema from JSON data the key names will be
used in the resulting Avro schema" +
+ " definition. When inferring from CSV data a \"header definition\"
must be present either as the first line of the incoming data" +
+ " or the \"header definition\" must be explicitly set in the
property \"CSV Header Definition\". A \"header definition\"" +
+ " is simply a single comma separated line defining the names of
each column. The \"header definition\" is" +
+ " required in order to determine the names that should be given to
each field in the resulting Avro definition." +
+ " When inferring data types the higher order data type is always
used if there is ambiguity." +
+ " For example when examining numerical values the type may be set
to \"long\" instead of \"integer\" since a long can" +
+ " safely hold the value of any \"integer\". Only CSV and JSON
content is currently supported for automatically inferring an" +
+ " Avro schema. The type of content present in the incoming
FlowFile is set by using the property \"Input Content Type\"." +
+ " The property can either be explicitly set to CSV, JSON, or \"use
mime.type value\" which will examine the" +
+ " value of the mime.type attribute on the incoming FlowFile to
determine the type of content present.")
+@ReadsAttributes({
+ @ReadsAttribute(attribute = "mime.type", description = "If
configured by property \"Input Content Type\" will" +
+ " use this value to determine what sort of content should
be inferred from the incoming FlowFile content."),
+})
+@WritesAttributes({
+ @WritesAttribute(attribute = "inferred.avro.schema", description =
"If configured by \"Schema output destination\" to" +
+ " write to an attribute this will hold the resulting Avro
schema from inferring the incoming FlowFile content."),
+})
+public class InferAvroSchema
+ extends AbstractKiteProcessor {
+
+ public static final String CSV_DELIMITER = ",";
+ public static final String USE_MIME_TYPE = "use mime.type value";
+ public static final String JSON_CONTENT = "json";
+ public static final String CSV_CONTENT = "csv";
+
+ public static final String AVRO_SCHEMA_ATTRIBUTE_NAME =
"inferred.avro.schema";
+ public static final String DESTINATION_ATTRIBUTE =
"flowfile-attribute";
+ public static final String DESTINATION_CONTENT = "flowfile-content";
+ public static final String JSON_MIME_TYPE = "application/json";
+ public static final String CSV_MIME_TYPE = "text/csv";
+ public static final String AVRO_MIME_TYPE = "application/avro-binary";
+ public static final String AVRO_FILE_EXTENSION = ".avro";
+
+ public static final PropertyDescriptor SCHEMA_DESTINATION = new
PropertyDescriptor.Builder()
+ .name("Schema output destination")
+ .description("Control if Avro schema is written as a new
flowfile attribute '" + AVRO_SCHEMA_ATTRIBUTE_NAME + "' " +
+ "or written in the flowfile content. Writing to
flowfile content will overwrite any " +
+ "existing flowfile content.")
+ .required(true)
+ .allowableValues(DESTINATION_ATTRIBUTE, DESTINATION_CONTENT)
+ .defaultValue(DESTINATION_CONTENT)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor INPUT_CONTENT_TYPE = new
PropertyDescriptor.Builder()
+ .name("Input Content Type")
+ .description("Content Type of data present in the incoming
FlowFile's content. Only \"" +
+ JSON_CONTENT + "\" or \"" + CSV_CONTENT + "\" are
supported." +
+ " If this value is set to \"" + USE_MIME_TYPE + "\"
the incoming Flowfile's attribute \"" + CoreAttributes.MIME_TYPE + "\"" +
+ " will be used to determine the Content Type.")
+ .allowableValues(USE_MIME_TYPE, JSON_CONTENT, CSV_CONTENT)
+ .defaultValue(USE_MIME_TYPE)
+ .required(true)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor
GET_CSV_HEADER_DEFINITION_FROM_INPUT = new PropertyDescriptor.Builder()
+ .name("Get CSV header definition from data")
+ .description("This property only applies to CSV content type.
If \"true\" the processor will attempt to read the CSV header definition from
the ")
+ .required(true)
+ .allowableValues("true", "false")
+ .defaultValue("true")
+ .addValidator(StandardValidators.BOOLEAN_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor CSV_HEADER_DEFINITION = new
PropertyDescriptor.Builder()
+ .name("CSV Header Definition")
+ .description("This property only applies to CSV content type.
Comma separated string defining the column names expected in the CSV data." +
+ " EX: \"fname,lname,zip,address\". The elements
present in this string should be in the same order" +
+ " as the underlying data. Setting this property will
cause the value of" +
+ " \"" + GET_CSV_HEADER_DEFINITION_FROM_INPUT.getName()
+ "\" to be ignored instead using this value.")
+ .required(false)
+ .expressionLanguageSupported(true)
+ .defaultValue(null)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+
+ public static final PropertyDescriptor HEADER_LINE_SKIP_COUNT = new
PropertyDescriptor.Builder()
+ .name("CSV Header Line Skip Count")
+ .description("This property only applies to CSV content type.
Specifies the number of lines that should be skipped when reading the CSV
data." +
+ " Setting this value to 0 is equivalent to saying
\"the entire contents of the file should be read\". If the" +
+ " property \"" +
GET_CSV_HEADER_DEFINITION_FROM_INPUT.getName() + "\" is set then the first line
of the CSV " +
+ " file will be read in and treated as the CSV header
definition. Since this will remove the header line from the data" +
+ " care should be taken to make sure the value of \"CSV
header Line Skip Count\" is set to 0 to ensure" +
+ " no data is skipped.")
+ .required(true)
+ .defaultValue("0")
+ .expressionLanguageSupported(true)
+
.addValidator(StandardValidators.NON_NEGATIVE_INTEGER_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor ESCAPE_STRING = new
PropertyDescriptor.Builder()
+ .name("CSV escape string")
+ .description("This property only applies to CSV content type.
String that represents an escape sequence" +
+ " in the CSV FlowFile content data.")
+ .required(true)
+ .defaultValue("\\")
+ .expressionLanguageSupported(true)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor QUOTE_STRING = new
PropertyDescriptor.Builder()
+ .name("CSV quote string")
+ .description("This property only applies to CSV content type.
String that represents a literal quote" +
+ " character in the CSV FlowFile content data.")
+ .required(true)
+ .defaultValue("'")
+ .expressionLanguageSupported(true)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor RECORD_NAME = new
PropertyDescriptor.Builder()
+ .name("Avro Record Name")
+ .description("Value to be placed in the Avro record schema
\"name\" field.")
+ .required(true)
+ .expressionLanguageSupported(true)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor CHARSET = new
PropertyDescriptor.Builder()
+ .name("Charset")
+ .description("Character encoding of CSV data.")
+ .required(true)
+ .defaultValue("UTF-8")
+ .addValidator(StandardValidators.CHARACTER_SET_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor PRETTY_AVRO_OUTPUT = new
PropertyDescriptor.Builder()
+ .name("Pretty Avro Output")
+ .description("If true the Avro output will be formatted.")
+ .required(true)
+ .defaultValue("true")
+ .allowableValues("true", "false")
+ .addValidator(StandardValidators.BOOLEAN_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor NUM_RECORDS_TO_ANALYZE = new
PropertyDescriptor.Builder()
+ .name("Number of records to analyze")
+ .description("This property only applies to JSON content type.
The number of JSON records that should be" +
+ " examined to determine the Avro schema. The higher
the value the better chance kite has of detecting" +
+ " the appropriate type. However the default value of
10 is almost always enough.")
+ .required(true)
+ .defaultValue("10")
+ .expressionLanguageSupported(true)
+
.addValidator(StandardValidators.NON_NEGATIVE_INTEGER_VALIDATOR)
+ .build();
+
+
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder().name("success")
+ .description("Successfully created Avro schema for CSV
data.").build();
+
+ public static final Relationship REL_ORIGINAL = new
Relationship.Builder().name("original")
+ .description("Original incoming FlowFile CSV data").build();
+
+ public static final Relationship REL_FAILURE = new
Relationship.Builder().name("failure")
+ .description("Failed to create Avro schema for CSV
data.").build();
+
+ public static final Relationship REL_UNSUPPORTED_CONTENT = new
Relationship.Builder().name("unsupported content")
+ .description("The content found in the flowfile content is not
of the required format.").build();
+
+ private List<PropertyDescriptor> properties;
+ private Set<Relationship> relationships;
+
+ @Override
+ protected void init(final ProcessorInitializationContext context) {
+ final List<PropertyDescriptor> properties = new ArrayList<>();
+ properties.add(SCHEMA_DESTINATION);
+ properties.add(INPUT_CONTENT_TYPE);
+ properties.add(CSV_HEADER_DEFINITION);
+ properties.add(GET_CSV_HEADER_DEFINITION_FROM_INPUT);
+ properties.add(HEADER_LINE_SKIP_COUNT);
+ properties.add(ESCAPE_STRING);
+ properties.add(QUOTE_STRING);
+ properties.add(PRETTY_AVRO_OUTPUT);
+ properties.add(RECORD_NAME);
+ properties.add(NUM_RECORDS_TO_ANALYZE);
+ properties.add(CHARSET);
+ this.properties = Collections.unmodifiableList(properties);
+
+ final Set<Relationship> relationships = new HashSet<>();
+ relationships.add(REL_SUCCESS);
+ relationships.add(REL_FAILURE);
+ relationships.add(REL_ORIGINAL);
+ relationships.add(REL_UNSUPPORTED_CONTENT);
+ this.relationships = Collections.unmodifiableSet(relationships);
+ }
+
+ @Override
+ protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+ return properties;
+ }
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ return relationships;
+ }
+
+
+ @Override
+ public void onTrigger(final ProcessContext context, final
ProcessSession session) throws ProcessException {
+ final FlowFile original = session.get();
+ if (original == null) {
+ return;
+ }
+
+ try {
+
+ final AtomicReference<String> avroSchema = new
AtomicReference<>();
+ switch (context.getProperty(INPUT_CONTENT_TYPE).getValue()) {
+ case USE_MIME_TYPE:
+ avroSchema.set(inferAvroSchemaFromMimeType(original,
context, session).get());
+ break;
+ case JSON_CONTENT:
+ avroSchema.set(inferAvroSchemaFromJSON(original,
context, session).get());
+ break;
+ case CSV_CONTENT:
+ avroSchema.set(inferAvroSchemaFromCSV(original,
context, session).get());
+ break;
+ default:
+ //Shouldn't be possible but just in case
+ session.transfer(original, REL_UNSUPPORTED_CONTENT);
+ break;
+ }
+
+
+ if (StringUtils.isNotEmpty(avroSchema.get())) {
+
+ String destination =
context.getProperty(SCHEMA_DESTINATION).getValue();
+ FlowFile avroSchemaFF = null;
+
+ switch (destination) {
+ case DESTINATION_ATTRIBUTE:
+ avroSchemaFF =
session.putAttribute(session.clone(original), AVRO_SCHEMA_ATTRIBUTE_NAME,
avroSchema.get());
+ //Leaves the original CoreAttributes.MIME_TYPE in
place.
+ break;
+ case DESTINATION_CONTENT:
+ avroSchemaFF = session.write(session.create(), new
OutputStreamCallback() {
+ @Override
+ public void process(OutputStream out) throws
IOException {
+ out.write(avroSchema.get().getBytes());
+ }
+ });
+ avroSchemaFF = session.putAttribute(avroSchemaFF,
CoreAttributes.MIME_TYPE.key(), AVRO_MIME_TYPE);
+ break;
+ default:
+ break;
+ }
+
+ //Transfer the sessions.
+ avroSchemaFF = session.putAttribute(avroSchemaFF,
CoreAttributes.FILENAME.key(),
(original.getAttribute(CoreAttributes.FILENAME.key()) + AVRO_FILE_EXTENSION));
+ session.transfer(avroSchemaFF, REL_SUCCESS);
+ } else {
+ //If the avroSchema is null then the content type is
unknown and therefore unsupported
+ session.transfer(session.clone(original),
REL_UNSUPPORTED_CONTENT);
+ }
+
+ session.transfer(original, REL_ORIGINAL);
+
+ } catch (Exception ex) {
+ getLogger().error("Failed to infer Avro schema! {}", ex);
+ session.transfer(original, REL_FAILURE);
+ }
+ }
+
+
+ /**
+ * Infers the Avro schema from the input Flowfile content. To infer an
Avro schema for CSV content a header line is
+ * required. You can configure the processor to pull that header line
from the first line of the CSV data if it is
+ * present OR you can manually supply the desired header line as a
property value.
+ *
+ * @param inputFlowFile
+ * The original input FlowFile containing the CSV content as it
entered this processor.
+ *
+ * @param context
+ * ProcessContext to pull processor configurations.
+ *
+ * @param session
+ * ProcessSession to transfer FlowFiles
+ */
+ private AtomicReference<String> inferAvroSchemaFromCSV(final FlowFile
inputFlowFile, final ProcessContext context, final ProcessSession session) {
--- End diff --
Why are we returning AtomicReference<String> instead of just String here?
It appears that when we get the value above, we immediately just call get() on
it
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