exceptionfactory commented on code in PR #4797: URL: https://github.com/apache/nifi/pull/4797#discussion_r991413387
########## nifi-nar-bundles/nifi-jslt-bundle/nifi-jslt-processors/src/main/java/org/apache/nifi/processors/jslt/JSLTTransformJSON.java: ########## @@ -0,0 +1,254 @@ +/* + * 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.JsonParseException; +import com.fasterxml.jackson.databind.JsonNode; +import com.fasterxml.jackson.databind.ObjectMapper; +import com.fasterxml.jackson.databind.ObjectWriter; +import com.github.benmanes.caffeine.cache.Cache; +import com.github.benmanes.caffeine.cache.Caffeine; +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.InputRequirement; +import org.apache.nifi.annotation.behavior.SideEffectFree; +import org.apache.nifi.annotation.behavior.SupportsBatching; +import org.apache.nifi.annotation.behavior.SystemResource; +import org.apache.nifi.annotation.behavior.SystemResourceConsideration; +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; + +@SideEffectFree +@SupportsBatching +@Tags({"json", "jslt", "transform"}) +@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED) +@SystemResourceConsideration(resource = SystemResource.MEMORY) +@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 JSLT 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-transformation") + .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("jslt-transform-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 PropertyDescriptor TRANSFORM_CACHE_SIZE = new PropertyDescriptor.Builder() + .name("jslt-transform-cache-size") + .displayName("Transform Cache Size") + .description("Compiling a JSLT Transform can be fairly expensive. Ideally, this will be done only once. However, if the Expression Language is used in the transform, we may need " + + "a new Transform for each FlowFile. This value controls how many of those Transforms we cache in memory in order to avoid having to compile the Transform each time.") + .expressionLanguageSupported(ExpressionLanguageScope.NONE) + .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR) + .defaultValue("1") + .required(true) + .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 ObjectMapper jsonObjectMapper = new ObjectMapper(); + + /** + * A cache for transform objects. It keeps values indexed by JSLT specification string. + */ + private Cache<String, Expression> transformCache; + + @Override + protected void init(final ProcessorInitializationContext context) { + final List<PropertyDescriptor> descriptors = new ArrayList<>(); + descriptors.add(JSLT_TRANSFORM); + descriptors.add(PRETTY_PRINT); + descriptors.add(TRANSFORM_CACHE_SIZE); + 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 { + 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) { + int maxTransformsToCache = context.getProperty(TRANSFORM_CACHE_SIZE).asInteger(); + transformCache = Caffeine.newBuilder() + .maximumSize(maxTransformsToCache) + .build(); + // 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 { + transformCache.put(transform, 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)) { + firstJsonNode = readJson(in); + } catch (final Exception e) { + logger.error("Failed to transform {}; routing to failure", original, e); + session.transfer(original, REL_FAILURE); + return; + } + + try { + final String transform = context.getProperty(JSLT_TRANSFORM).evaluateAttributeExpressions(original).getValue(); + Expression jsltExpression = transformCache.get(transform, currString -> Parser.compileString(transform)); + + final JsonNode transformedJson = jsltExpression.apply(firstJsonNode); + final ObjectWriter writer = context.getProperty(PRETTY_PRINT).asBoolean() ? jsonObjectMapper.writerWithDefaultPrettyPrinter() : jsonObjectMapper.writer(); + final Object outputObject; + if (transformedJson == null || transformedJson.isNull()) { + logger.warn("JSLT transform resulted in no data"); + outputObject = null; + } else { + outputObject = transformedJson; + } + FlowFile transformed = session.write(original, out -> { + if (outputObject != null) { + writer.writeValue(out, outputObject); + } + }); + transformed = session.putAttribute(transformed, CoreAttributes.MIME_TYPE.key(), "application/json"); + session.transfer(transformed, REL_SUCCESS); + session.getProvenanceReporter().modifyContent(transformed, "Modified With " + transform, stopWatch.getElapsed(TimeUnit.MILLISECONDS)); Review Comment: Is this manual call to Provenance Reporter still necessary? -- This is an automated message from the Apache Git Service. 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