gemini-code-assist[bot] commented on code in PR #35952:
URL: https://github.com/apache/beam/pull/35952#discussion_r2322407191
##########
sdks/python/apache_beam/yaml/yaml_transform.py:
##########
@@ -522,6 +548,241 @@ def expand_leaf_transform(spec, scope):
f'{type(outputs)}')
+def expand_output_schema_transform(spec, outputs, error_handling_spec):
+ """Applies a `Validate` transform to the output of another transform.
+
+ This function is called when an `output_schema` is defined on a transform.
+ It wraps the original transform's output(s) with a `Validate` transform
+ to ensure the data conforms to the specified schema.
+
+ If the original transform has error handling configured, validation errors
+ will be routed to the specified error output. If not, validation failures
+ will cause the pipeline to fail.
+
+ Args:
+ spec (dict): The `output_schema` specification from the YAML config.
+ outputs (beam.PCollection or dict[str, beam.PCollection]): The output(s)
+ from the transform to be validated.
+ error_handling_spec (dict): The `error_handling` configuration from the
+ original transform.
+
+ Returns:
+ The validated PCollection(s). If error handling is enabled, this will be a
+ dictionary containing the 'good' output and any error outputs.
+
+ Raises:
+ ValueError: If `error_handling` is incorrectly specified within the
+ `output_schema` spec itself, or if the main output of a multi-output
+ transform cannot be determined.
+ """
+ if 'error_handling' in spec:
+ raise ValueError(
+ 'error_handling config is not supported directly in '
+ 'the output_schema. Please use error_handling config in '
+ 'the transform.')
+
+ # Strip metadata such as __line__ and __uuid__ as these will interfere with
+ # the validation downstream.
+ clean_schema = SafeLineLoader.strip_metadata(spec)
+
+ # If no error handling is specified for the main transform, warn the user
+ # that the pipeline may fail if any output data fails the output schema
+ # validation.
+ if not error_handling_spec:
+ _LOGGER.warning("Output_schema config is attached to a transform that has
"\
+ "no error_handling config specified. Any failures validating on output" \
+ "schema will fail the pipeline unless the user specifies an" \
+ "error_handling config on a capable transform or the user can remove the" \
+ "output_schema config on this transform and add a ValidateWithSchema " \
+ "transform downstream of the current transform.")
Review Comment:
There's a small typo in the warning message. `outputschema` should be
`output schema`. Correcting this will improve clarity for users who encounter
this warning.
```python
_LOGGER.warning(
"Output_schema config is attached to a transform that has "
"no error_handling config specified. Any failures validating on output "
"schema will fail the pipeline unless the user specifies an "
"error_handling config on a capable transform or the user can remove the
"
"output_schema config on this transform and add a ValidateWithSchema "
"transform downstream of the current transform.")
```
##########
website/www/site/content/en/documentation/sdks/yaml-schema.md:
##########
@@ -0,0 +1,119 @@
+---
+type: languages
+title: "Apache Beam YAML Schema"
+---
+<!--
+ 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.
+-->
+
+# Beam YAML Schema
+
+As pipelines grow in size and complexity, it becomes more common to encounter
+data that is malformed, doesn't meet preconditions, or otherwise causes issues
+during processing.
+
+Beam YAML helps the user detect and capture these issues by using the optional
+`output_schema` configuration, which is available for any transform in the YAML
+SDK. For example, the following code creates a few "good" records and specifies
+that the output schema from the `Create` transform should have records that
+follow the expected schema: `sdk` as a string and `year` as an integer.
+
+```yaml
+pipeline:
+ type: chain
+ transforms:
+ - type: Create
+ config:
+ elements:
+ - {sdk: MapReduce, year: 2004}
+ - {sdk: MillWheel, year: 2008}
+ output_schema:
+ type: object
+ properties:
+ sdk:
+ type: string
+ year:
+ type: integer
+ - type: AssertEqual
+ config:
+ elements:
+ - {sdk: MapReduce, year: 2004}
+ - {sdk: MillWheel, year: 2008}
+```
+
+However, a user will more likely want to detect and handle schema errors. If a
+transform has a built-in error_handling configuration, the user can specify
that
+error_handling configuration and any errors found will be appended to the
+transform error_handling output. For example, the following code will
+create a few "good" and "bad" records with a specified schema of `user` as a
+string and `timestamp` as a boolean. The `alice` row will fail in the standard
+way because of not being an integer for the AssignTimestamps transform, while
+the `bob` row will fail because after the AssignTimestamp transformation, the
+output row will have the timestamp as an integer when it should be a boolean.
+
+
+```yaml
+pipeline:
+ type: composite
+ transforms:
+ - type: Create
+ name: CreateVisits
+ config:
+ elements:
+ - {user: alice, timestamp: "not-valid"}
+ - {user: bob, timestamp: 3}
+ - type: AssignTimestamps
+ input: CreateVisits
+ config:
+ timestamp: timestamp
+ error_handling:
+ output: invalid_rows
+ output_schema:
+ type: object
+ properties:
+ user:
+ type: string
+ timestamp:
+ type: boolean
+ - type: MapToFields
+ name: ExtractInvalidTimestamp
+ input: AssignTimestamps.invalid_rows
+ config:
+ language: python
+ fields:
+ user: "element.user"
+ timestamp: "element.timestamp"
+ - type: AssertEqual
+ input: ExtractInvalidTimestamp
+ config:
+ elements:
+ - {user: "alice", timestamp: "not-valid"}
+ - {user: bob, timestamp: 3}
+ - type: AssertEqual
+ input: AssignTimestamps
+ config:
+ elements: []
+```
+
+WARNING: If a transform doesn't have the error_handling configuration available
+and a user chooses to use this optional output_schema feature, any failures
+found will result in the entire pipeline failing. If the user would still like
+to have somekind of output schema validation, please use the ValidateWithSchema
+transform instead.
Review Comment:
There's a typo in the documentation. `somekind` should be `some kind`.
```suggestion
to have some kind of output schema validation, please use the
ValidateWithSchema
transform instead.
```
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