NIFI-15057 - Add Record Path like helper methods for Record Transform Python processors

nifi-docs/src/main/asciidoc/python-developer-guide.adoc

@@ -283,6 +283,30 @@ If the partition has more than one field in the dictionary, all fields in the di
 the Records to be written to the same output FlowFile.
 
 
+==== Working with Record Paths
+
+Manipulating just a small portion of an incoming record is a very common use case for `RecordTransform` processors. To make
+this easier the Python API exposes the helper function `nifiapi.recordpath.evaluate(record, schema, record_path)`.
+
+The helper accepts the record dictionary, the optional schema supplied by NiFi, and a simple RecordPath-like expression. The
+syntax supports forward-slash navigation and zero-based list indexes such as `/customer/address/street` or `/items[0]/price`.
+The function returns an iterable collection of field wrapper objects. Each wrapper exposes `get_value()` and `set_value(...)`
+methods so you can read and update the targeted value without walking the nested dictionary yourself. Any call to
+`set_value(...)` automatically updates the backing record. Example:
+
+----
+path_result = recordpath.evaluate(record, schema, '/my/example')
+for field in path_result:
+    value = field.get_value()
+    if value is not None:
+        field.set_value(hashlib.sha256(str(value).encode('utf-8')).hexdigest())
+----
+
+Because `recordpath.evaluate` returns wrappers, the loop above will transparently update the original record. When the
+processor returns the modified record via `RecordTransformResult`, NiFi writes the new value using the configured Record
+Reader and Record Writer services.
+
+
 [[flowfile-source]]
 === FlowFileSource
 

nifi-extension-bundles/nifi-py4j-extension-bundle/nifi-py4j-integration-tests/src/test/java/org.apache.nifi.py4j/PythonControllerInteractionIT.java

@@ -17,6 +17,8 @@
 
 package org.apache.nifi.py4j;
 
+import org.apache.commons.codec.digest.DigestUtils;
+
 import org.apache.nifi.components.AsyncLoadedProcessor;
 import org.apache.nifi.components.AsyncLoadedProcessor.LoadState;
 import org.apache.nifi.components.state.Scope;
@@ -470,8 +472,75 @@ public void testRecordTransformWithDynamicProperties() throws InitializationExce
     }
 
 
+    @Test
+    public void testHashRecordFieldHappyPath() throws InitializationException {
+        final TestRunner runner = createRecordTransformRunner("HashRecordField");
+        runner.setProperty("Record Path", "/my/example");
+
+        final String json = "[{\"foo\":\"foo\",\"my\":{\"example\":\"value\"}}]";
+        runner.enqueue(json);
+        waitForValid(runner);
+        runner.run();
+
+        runner.assertTransferCount("success", 1);
+        runner.assertTransferCount("original", 1);
+        final MockFlowFile out = runner.getFlowFilesForRelationship("success").get(0);
+        final String expectedHash = DigestUtils.sha256Hex("value");
+        out.assertContentEquals("[{\"foo\":\"foo\",\"my\":{\"example\":\"" + expectedHash + "\"}}]");
+    }
+
+    @Test
+    public void testHashRecordFieldMissingField() throws InitializationException {
+        final TestRunner runner = createRecordTransformRunner("HashRecordField");
+        runner.setProperty("Record Path", "/does/not/exist");
+
+        final String json = "[{\"foo\":\"foo\",\"my\":{\"example\":\"value\"}}]";
+        runner.enqueue(json);
+        waitForValid(runner);
+        runner.run();
+
+        runner.assertTransferCount("success", 1);
+        runner.assertTransferCount("original", 1);
+        final MockFlowFile out = runner.getFlowFilesForRelationship("success").get(0);
+        out.assertContentEquals("[{\"foo\":\"foo\",\"my\":{\"example\":\"value\"}}]");
+    }
+
+    @Test
+    public void testHashRecordFieldNonScalar() throws InitializationException {
+        final TestRunner runner = createRecordTransformRunner("HashRecordField");
+        runner.setProperty("Record Path", "/my");
+
+        final String json = "[{\"foo\":\"foo\",\"my\":{\"example\":\"value\"}}]";
+        runner.enqueue(json);
+        waitForValid(runner);
+        runner.run();
+
+        runner.assertTransferCount("success", 1);
+        runner.assertTransferCount("original", 1);
+        final MockFlowFile out = runner.getFlowFilesForRelationship("success").get(0);
+        out.assertContentEquals("[{\"foo\":\"foo\",\"my\":{\"example\":\"value\"}}]");
+    }
+
+    @Test
+    public void testHashRecordFieldLongValue() throws InitializationException {
+        final TestRunner runner = createRecordTransformRunner("HashRecordField");
+        runner.setProperty("Record Path", "/count");
+
+        final String json = "[{\"count\":7}]";
+        runner.enqueue(json);
+        waitForValid(runner);
+        runner.run();
+
+        runner.assertTransferCount("success", 1);
+        runner.assertTransferCount("original", 1);
+        final MockFlowFile out = runner.getFlowFilesForRelationship("success").get(0);
+        final String expectedHash = DigestUtils.sha256Hex("7");
+        out.assertContentEquals("[{\"count\":\"" + expectedHash + "\"}]");
+    }
+
+
     private TestRunner createRecordTransformRunner(final String type) throws InitializationException {
-        final TestRunner runner = createProcessor("SetRecordField");
+        final TestRunner runner = createProcessor(type);
         runner.setValidateExpressionUsage(false);
 
         final JsonTreeReader reader = new JsonTreeReader();
@@ -487,6 +556,7 @@ private TestRunner createRecordTransformRunner(final String type) throws Initial
         return runner;
     }
 
+
     @Test
     public void testRecordTransformWithInnerRecord() throws InitializationException {
         // Create a SetRecordField Processor

nifi-extension-bundles/nifi-py4j-extension-bundle/nifi-python-test-extensions/src/main/resources/extensions/HashRecordField.py

@@ -0,0 +1,72 @@
+# 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.
+
+import hashlib
+
+from nifiapi.properties import PropertyDescriptor, StandardValidators
+from nifiapi.recordtransform import RecordTransform, RecordTransformResult
+from nifiapi import recordpath
+
+
+class HashRecordField(RecordTransform):
+    class Java:
+        implements = ['org.apache.nifi.python.processor.RecordTransform']
+
+    class ProcessorDetails:
+        version = '0.0.1-SNAPSHOT'
+        description = 'Hashes a record field using SHA-256.'
+        tags = ['record', 'hash', 'security']
+
+    def __init__(self, **kwargs):
+        super().__init__()
+        self.record_path = PropertyDescriptor(
+            name='Record Path',
+            description='The RecordPath identifying the field that should be hashed.',
+            required=True,
+            validators=[StandardValidators.NON_EMPTY_VALIDATOR]
+        )
+        self.descriptors = [self.record_path]
+
+    def getPropertyDescriptors(self):
+        return self.descriptors
+
+    def transform(self, context, record, schema, attributemap):
+        record_path_value = context.getProperty(self.record_path.name).getValue()
+        if not record_path_value:
+            return RecordTransformResult(record=record, schema=schema, relationship='success')
+
+        path_result = recordpath.evaluate(record, schema, record_path_value)
+        if path_result.is_empty():
+            self.logger.warn('Record Path {} did not resolve to a value; record left unchanged'.format(record_path_value))
+            return RecordTransformResult(record=record, schema=schema, relationship='success')
+
+        for field in path_result:
+            value = field.get_value()
+            if value is None:
+                continue
+            if isinstance(value, (dict, list)):
+                self.logger.warn('Record Path {} resolved to a non-scalar value; skipping hash operation'.format(record_path_value))
+                continue
+            try:
+                value_as_string = value if isinstance(value, str) else str(value)
+                hashed = hashlib.sha256(value_as_string.encode('utf-8')).hexdigest()
+            except Exception as exc:
+                self.logger.error('Failed to hash value at {}: {}'.format(record_path_value, exc))
+                continue
+            field.set_value(hashed)
+
+        path_result.apply()
+
+        return RecordTransformResult(record=record, schema=schema, relationship='success')

nifi-framework-bundle/nifi-framework-extensions/nifi-py4j-framework-bundle/nifi-python-extension-api/src/main/python/src/nifiapi/recordpath.py

@@ -0,0 +1,129 @@
+# 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.
+
+
+def evaluate(record, schema, record_path):
+    """Evaluate a RecordPath-like expression against the provided record.
+
+    This lightweight implementation supports simple '/' separated paths with
+    optional zero-based list indexes (for example '/parent/child[0]'). It
+    returns wrappers that allow callers to read or update the targeted value.
+    """
+    if record is None or record_path is None:
+        return RecordPathResult(record, None, [], dirty=False)
+
+    wrappers = _evaluate_simple_path(record, record_path)
+    return RecordPathResult(record, None, wrappers, dirty=False)
+
+
+def _evaluate_simple_path(record, record_path):
+    tokens = [segment for segment in record_path.split('/') if segment]
+    if not tokens:
+        return []
+
+    current = record
+    parent = None
+    key = None
+
+    for token in tokens:
+        if '[' in token and token.endswith(']'):
+            base, index_text = token.split('[', 1)
+            index_text = index_text[:-1]
+        else:
+            base, index_text = token, None
+
+        if not isinstance(current, dict) or base not in current:
+            return []
+
+        parent = current
+        key = base
+        current = current[base]
+
+        if index_text is not None:
+            if not isinstance(current, list):
+                return []
+            try:
+                index = int(index_text)
+            except ValueError:
+                return []
+            if index < 0 or index >= len(current):
+                return []
+            parent = current
+            key = index
+            current = current[index]
+
+    if parent is None:
+        return []
+
+    return [_SimpleFieldValueWrapper(parent, key)]
+
+
+class RecordPathResult:
+    def __init__(self, python_record, java_record, field_wrappers, dirty=True):
+        self._python_record = python_record
+        self._java_record = java_record
+        self._field_wrappers = field_wrappers
+        self._dirty = False
+
+        for wrapper in self._field_wrappers:
+            wrapper._attach(self)
+
+    def __iter__(self):
+        return iter(self._field_wrappers)
+
+    def is_empty(self):
+        return len(self._field_wrappers) == 0
+
+    def fields(self):
+        return list(self._field_wrappers)
+
+    def apply(self):
+        return self._python_record
+
+    def _mark_dirty(self):
+        self._dirty = True
+
+
+class _SimpleFieldValueWrapper:
+    def __init__(self, parent, key):
+        self._parent = parent
+        self._key = key
+        self._parent_result = None
+
+    def _attach(self, parent_result):
+        self._parent_result = parent_result
+
+    def get_value(self):
+        try:
+            return self._parent[self._key]
+        except Exception:
+            return None
+
+    def set_value(self, new_value):
+        self.update_value(new_value)
+
+    def update_value(self, new_value):
+        try:
+            self._parent[self._key] = new_value
+            if self._parent_result is not None:
+                self._parent_result._mark_dirty()
+        except Exception:
+            pass
+
+    def get_field(self):
+        return None
+
+    def get_parent(self):
+        return None