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Posted to issues@nifi.apache.org by GitBox <gi...@apache.org> on 2021/02/02 10:43:22 UTC
[GitHub] [nifi] Lehel44 commented on a change in pull request #4797: NIFI-8111: Add JSLTTransformJSON processor
Lehel44 commented on a change in pull request #4797:
URL: https://github.com/apache/nifi/pull/4797#discussion_r568500363
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File path: nifi-nar-bundles/nifi-jslt-bundle/nifi-jslt-processors/src/main/java/org/apache/nifi/processors/jslt/JSLTTransformJSON.java
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@@ -0,0 +1,237 @@
+/*
+ * 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.jslt;
+
+import com.fasterxml.jackson.core.JsonFactory;
+import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.schibsted.spt.data.jslt.Expression;
+import com.schibsted.spt.data.jslt.JsltException;
+import com.schibsted.spt.data.jslt.Parser;
+import org.apache.nifi.annotation.behavior.EventDriven;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.SideEffectFree;
+import org.apache.nifi.annotation.behavior.SupportsBatching;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnShutdown;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.flowfile.attributes.CoreAttributes;
+import org.apache.nifi.logging.ComponentLog;
+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.util.StandardValidators;
+import org.apache.nifi.util.StopWatch;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+@EventDriven
+@SideEffectFree
+@SupportsBatching
+@Tags({"json", "jslt", "transform"})
+@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
+@WritesAttribute(attribute = "mime.type", description = "Always set to application/json")
+@CapabilityDescription("Applies a JSLT transformation to the flowfile JSON payload. A new FlowFile is created "
+ + "with transformed content and is routed to the 'success' relationship. If the JSON transform "
+ + "fails, the original FlowFile is routed to the 'failure' relationship.")
+public class JSLTTransformJSON extends AbstractProcessor {
+
+ public static final PropertyDescriptor JSLT_TRANSFORM = new PropertyDescriptor.Builder()
+ .name("jslt-transform")
+ .displayName("JSLT Transformation")
+ .description("JSLT Transformation for transform of JSON data. Any NiFi Expression Language present will be evaluated first to get the final transform to be applied.")
+ .expressionLanguageSupported(ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .required(true)
+ .build();
+
+ public static final PropertyDescriptor PRETTY_PRINT = new PropertyDescriptor.Builder()
+ .name("pretty_print")
+ .displayName("Pretty Print")
+ .description("Apply pretty-print formatting to the output of the JSLT transform")
+ .required(true)
+ .allowableValues("true", "false")
+ .defaultValue("false")
+ .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 FlowFile is not valid JSON), it will be routed to this relationship")
+ .build();
+
+ private List<PropertyDescriptor> descriptors;
+ private Set<Relationship> relationships;
+ private static final JsonFactory jsonFactory = new JsonFactory();
+ private static final ObjectMapper codec = new ObjectMapper();
+ private final static String DEFAULT_CHARSET = "UTF-8";
+
+ private final AtomicReference<Expression> precompiledExpression = new AtomicReference<>();
+
+ @Override
+ protected void init(final ProcessorInitializationContext context) {
+ final List<PropertyDescriptor> descriptors = new ArrayList<>();
+ descriptors.add(JSLT_TRANSFORM);
+ descriptors.add(PRETTY_PRINT);
+ this.descriptors = Collections.unmodifiableList(descriptors);
+
+ 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 this.relationships;
+ }
+
+ @Override
+ public final List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+ return descriptors;
+ }
+
+ @Override
+ protected Collection<ValidationResult> customValidate(ValidationContext validationContext) {
+ final List<ValidationResult> results = new ArrayList<>(super.customValidate(validationContext));
+
+ // If no EL present, pre-compile the script (and report any errors as to mark the processor invalid)
+ if (!validationContext.getProperty(JSLT_TRANSFORM).isExpressionLanguagePresent()) {
+ final String transform = validationContext.getProperty(JSLT_TRANSFORM).getValue();
+ try {
+ precompiledExpression.set(Parser.compileString(transform));
+ } catch (JsltException je) {
+ results.add(new ValidationResult.Builder().subject(JSLT_TRANSFORM.getDisplayName()).valid(false).explanation("error in transform: " + je.getMessage()).build());
+ }
+ } else {
+ // Expression Language is present, we won't know if the transform is valid until the EL is evaluated
+ results.add(new ValidationResult.Builder().subject(JSLT_TRANSFORM.getDisplayName()).valid(true).build());
+ }
+ return results;
+
+ }
+
+ @OnScheduled
+ public void onScheduled(final ProcessContext context) {
+ // Precompile the transform if it hasn't been done already (and if there is no Expression Language present)
+ if (!context.getProperty(JSLT_TRANSFORM).isExpressionLanguagePresent()) {
+ final String transform = context.getProperty(JSLT_TRANSFORM).getValue();
+ try {
+ precompiledExpression.set(Parser.compileString(transform));
+ } catch (JsltException je) {
+ throw new ProcessException("Error compiling JSLT transform: " + je.getMessage(), je);
+ }
+ }
+ }
+
+ @Override
+ public void onTrigger(final ProcessContext context, final ProcessSession session) throws ProcessException {
+ final FlowFile original = session.get();
+ if (original == null) {
+ return;
+ }
+
+ final ComponentLog logger = getLogger();
+ final StopWatch stopWatch = new StopWatch(true);
+
+ JsonNode firstJsonNode;
+ try (final InputStream in = session.read(original)) {
+ try {
+ JsonParser jsonParser = jsonFactory.createParser(in);
+ jsonParser.setCodec(codec);
+
+ JsonToken token = jsonParser.nextToken();
+ if (token == JsonToken.START_ARRAY) {
+ token = jsonParser.nextToken(); // advance to START_OBJECT token
+ }
+
+ if (token == JsonToken.START_OBJECT) { // could be END_ARRAY also
+ firstJsonNode = jsonParser.readValueAsTree();
+ } else {
+ firstJsonNode = null;
+ }
+ } catch (final JsonParseException e) {
+ throw new IOException("Could not parse data as JSON", e);
+ }
+ } catch (final Exception e) {
+ logger.error("Failed to transform {}; routing to failure", new Object[]{original}, e);
+ session.transfer(original, REL_FAILURE);
+ return;
+ }
+
+ final String jsonString;
+ try {
+ Expression jsltExpression = precompiledExpression.get();
+
+ if (jsltExpression == null) {
+ final String transform = context.getProperty(JSLT_TRANSFORM).evaluateAttributeExpressions(original).getValue();
+ jsltExpression = Parser.compileString(transform);
+ }
+ final JsonNode transformedJson = jsltExpression.apply(firstJsonNode);
+ if (transformedJson == null) {
+ jsonString = "";
+ logger.info("JSLT transform resulted in no data!");
+ } else {
+ jsonString = context.getProperty(PRETTY_PRINT).asBoolean() ? transformedJson.toPrettyString() : transformedJson.toString();
+ }
+ } catch (final Exception ex) {
+ logger.error("Unable to transform {} due to {}", new Object[]{original, ex.toString()}, ex);
+ session.transfer(original, REL_FAILURE);
+ return;
+ }
+
+ FlowFile transformed = session.write(original, out -> out.write(jsonString.getBytes(DEFAULT_CHARSET)));
Review comment:
You could use
```suggestion
FlowFile transformed = session.write(original, out -> out.write(jsonString.getBytes(StandardCharsets.UTF_8)));
```
here.
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