[GitHub] [nifi] bbende commented on a change in pull request #4232: NIFI-7392: Initial commit for the ValidateJSON processor

[GitBox <gi...@apache.org>]

bbende commented on a change in pull request #4232:
URL: https://github.com/apache/nifi/pull/4232#discussion_r414670560



##########
File path: nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/ValidateJson.java
##########
@@ -0,0 +1,212 @@
+/*
+ * 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 org.apache.commons.io.IOUtils;
+import org.apache.nifi.components.AllowableValue;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+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.behavior.WritesAttributes;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.processor.exception.ProcessException;
+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.util.StandardValidators;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicReference;
+
+import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.networknt.schema.JsonSchema;
+import com.networknt.schema.JsonSchemaFactory;
+import com.networknt.schema.ValidationMessage;
+import com.networknt.schema.SpecVersion.VersionFlag;
+
+@EventDriven
+@SideEffectFree
+@SupportsBatching
+@InputRequirement(Requirement.INPUT_REQUIRED)
+@Tags({"JSON", "schema", "validation"})
+@WritesAttributes({
+    @WritesAttribute(attribute = "validatejson.invalid.error", description = "If the flow file is routed to the invalid relationship "
+            + "the attribute will contain the error message resulting from the validation failure.")
+})
+@CapabilityDescription("Validates the contents of FlowFiles against a user-specified JSON Schema file")
+public class ValidateJson extends AbstractProcessor {
+
+    public static final String ERROR_ATTRIBUTE_KEY = "validatejson.invalid.error";
+
+    public static final AllowableValue SCHEMA_VERSION_4 = new AllowableValue("V4");
+    public static final AllowableValue SCHEMA_VERSION_6 = new AllowableValue("V6");
+    public static final AllowableValue SCHEMA_VERSION_7 = new AllowableValue("V7");
+    public static final AllowableValue SCHEMA_VERSION_V201909 = new AllowableValue("V201909");
+
+    public static final PropertyDescriptor SCHEMA_VERSION = new PropertyDescriptor
+        .Builder().name("SCHEMA_VERSION")
+        .displayName("Schema Version")
+        .description("The JSON schema specification")
+        .required(true)
+        .allowableValues(SCHEMA_VERSION_4, SCHEMA_VERSION_6, SCHEMA_VERSION_7, SCHEMA_VERSION_V201909)
+        .defaultValue(SCHEMA_VERSION_V201909.getValue())
+        .build();
+
+    public static final PropertyDescriptor SCHEMA_TEXT = new PropertyDescriptor
+        .Builder().name("SCHEMA_TEXT")
+        .displayName("Schema Text")
+        .description("The text of a JSON schema")
+        .required(true)
+        .expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+        .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+        .build();
+
+    public static final Relationship REL_VALID = new Relationship.Builder()
+        .name("valid")
+        .description("FlowFiles that are successfully validated against the schema are routed to this relationship")
+        .build();
+
+    public static final Relationship REL_INVALID = new Relationship.Builder()
+        .name("invalid")
+        .description("FlowFiles that are not valid according to the specified schema are routed to this relationship")
+        .build();
+
+    public static final Relationship REL_FAILURE = new Relationship.Builder()
+        .name("failure")
+        .description("FlowFiles that cannot be read as JSON are routed to this relationship")
+        .build();
+
+    private List<PropertyDescriptor> descriptors;
+
+    private Set<Relationship> relationships;
+
+    private List<AllowableValue> allowableValues;
+
+    @Override
+    protected void init(final ProcessorInitializationContext context) {
+        final List<PropertyDescriptor> descriptors = new ArrayList<PropertyDescriptor>();
+        descriptors.add(SCHEMA_TEXT);
+        descriptors.add(SCHEMA_VERSION);
+        this.descriptors = Collections.unmodifiableList(descriptors);
+
+        final Set<Relationship> relationships = new HashSet<Relationship>();
+        relationships.add(REL_VALID);
+        relationships.add(REL_INVALID);
+        relationships.add(REL_FAILURE);
+        this.relationships = Collections.unmodifiableSet(relationships);
+
+        final List<AllowableValue> allowableValues = new ArrayList<AllowableValue>();
+        allowableValues.add(SCHEMA_VERSION_4);
+        allowableValues.add(SCHEMA_VERSION_6);
+        allowableValues.add(SCHEMA_VERSION_7);
+        allowableValues.add(SCHEMA_VERSION_V201909);
+        this.allowableValues = Collections.unmodifiableList(allowableValues);
+
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return this.relationships;
+    }
+
+    @Override
+    public final List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return descriptors;
+    }
+
+    @Override
+    public void onTrigger(final ProcessContext context, final ProcessSession session) throws ProcessException {
+        FlowFile flowFile = session.get();
+        if ( flowFile == null ) {
+            return;
+        }
+
+        AtomicReference<String> flowFileContent = new AtomicReference<>(null);
+
+        // Read FlowFile contents into a String
+        session.read(flowFile, in -> {
+            flowFileContent.set(IOUtils.toString(in));

Review comment:
       Is there any way to validate the JSON using an InputStream? Generally it is best if we can avoid reading the entire content of a flow file into memory. If there is not a way then we would want to clearly document in the processor's documentation that this processor will read the entire flow file into memory.




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