feat(emitter):add structured data output with JSON and table formatting #380

dharapandya85 · 2025-08-25T04:24:27Z

Fixes : #348

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This PR extends the Emitter class to support structured data output in multiple formats(JSON,table), with a registry for adding formats.
Implementation Details

A method on the emitter to write structured data to stdout
Output methods: TableFormatter for human-readable tables,JSONFormatterfor machine-readable JSON
Implemented usage in examples.py
Unit tests covering all formatters and edge cases
Added Emitter.data() method which accepts structured data(list[dict]) and uses registered formatter based on the --format flag.
Implemented JSONFormatter to fetch JSON outputs with json.dumps
Implemented TableFormatter for printing rows and columns
Emitter.register_formate(name,formatter) allows registering new formats
Default registry includes JSON and table
Updated CLI (dispatcher.py) to add -- format{json,table}
Added example_36 in examples.py to demo usage.
Added unit tests in test_messages_emitter.py
TableFomattter, handles list of dicts, empty list and dict input
JSONFormatter serializes list of data

Example Run

python examples.py 36 table
>>> Running example_33 with args: ('table',)
TABLE output:
name  | status   | version
--------------------------
App A | active   | 1.0.1
App B | inactive | 2.3.0

python examples.py 36 json
>>> Running example_33 with args: ('json',)
JSON output:
[
  {
    "name": "App A",
    "version": "1.0.1",
    "status": "active"
  },
  {
    "name": "App B",
    "version": "2.3.0",
    "status": "inactive"
  }
]

lengau · 2025-09-09T20:15:11Z

craft_cli/messages.py

+class BaseFormatter(ABC):
+    @abstractmethod
+    def format(self,data:TabularData,headers:dict[str,str] | None=None)->str:
+        pass


Running make format should fix the formatting issue here

lengau

Hi, please fix the broken tests and lint errors here.

docs/how-to-guides/change-logfile.rst

…sertions

beliaev-maksim · 2025-11-27T11:33:01Z

craft_cli/pytest_plugin.py

+    # messages.emit._initiated = False
+    # messages.emit._stopped = True


should it be here?

beliaev-maksim · 2025-11-27T11:33:29Z

examples.py

+    # emit.message("Table output:")
+    # emit.data(sample_data,format="table")
+
+    # emit.structured(sample_data,fmt=fmt)


Problem solved, and no doc changes that require my review.

beliaev-maksim · 2025-12-04T11:56:16Z

pyproject.toml

-    "FBT002", # Boolean default value in function definition (preserving for backwards-comp)
-    "S101",   # Use of `assert` detected
-]
+


something looks wrong with this file. Lot's of unnecessary changes

Copilot

Pull request overview

This PR adds structured data output capabilities to the Emitter class, supporting JSON and table formatting for machine and human-readable output. The implementation includes a formatter registry pattern, CLI integration, and comprehensive test coverage.

Key changes:

Added BaseFormatter, JSONFormatter, and TableFormatter classes for flexible output formatting
Implemented Emitter.data(), Emitter.table(), and Emitter.json() methods for structured data output
Added --format CLI argument with json/table choices (filtered from help output)

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
craft_cli/messages.py	Core formatter classes and Emitter methods for structured data output
craft_cli/dispatcher.py	Added `--format` CLI argument and filtered it from command help
craft_cli/helptexts.py	Fixed help text generation when options list is empty
craft_cli/printer.py	Added `raw_output` parameter support to `show()` method
examples.py	Added example_36 demonstrating structured output formats
tests/unit/test_messages_emitter.py	Added unit tests for formatters and updated double init test
tests/unit/test_help.py	Updated tests to reflect filtered global options from help
tests/integration/test_messages_integration.py	Adjusted timing thresholds for test stability
craft_cli/init.py	Exposed `Emitter` and `complete` in public API
craft_cli/pytest_plugin.py	Added type ignore comments for pytest imports
craft_cli/completion/completion.py	Added explicit type annotation for template render
docs/conf.py	Added type ignore comment for sphinx import
pyproject.toml	File deleted (full file removal)

Comments suppressed due to low confidence (1)

pyproject.toml:1

The entire pyproject.toml file has been deleted. This removes critical project metadata, dependencies, and build configuration. This change should be reverted unless there's a deliberate migration to a different build system.

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Copilot · 2025-12-05T20:47:17Z

craft_cli/messages.py

+        """
+        formatter = self._formatters.get(output_format)
+        if not formatter:
+            raise ValueError(f"Unsupported format: {format}")


The error message references undefined variable format instead of the parameter output_format. This will raise a NameError.

Suggested change

raise ValueError(f"Unsupported format: {format}")

raise ValueError(f"Unsupported format: {output_format}")

Copilot · 2025-12-05T20:47:18Z

craft_cli/messages.py

+        _ = headers
+        """Format a list of rows into a table string."""


The docstring is placed after the parameter line and unused variable assignment. Move this docstring to line 84, immediately after the method signature.

Suggested change

_ = headers

"""Format a list of rows into a table string."""

"""Format a list of rows into a table string."""

_ = headers

Copilot · 2025-12-05T20:47:18Z

examples.py


+def example_36(*args: str) -> None:
+    """Demonstrate structured output formats."""
+    print(">>> Running example_36 with args:", args)


The message incorrectly refers to 'example_33' instead of 'example_36', as shown in the description. This appears to be a copy-paste error.

Copilot · 2025-12-05T20:47:18Z

craft_cli/messages.py

+
+    Example:
+    -------
+    >>> formatter = JsonFormatter()


Class name in docstring example should be JSONFormatter (matching the actual class name) instead of JsonFormatter.

Suggested change

>>> formatter = JsonFormatter()

>>> formatter = JSONFormatter()

Copilot · 2025-12-05T20:47:19Z

craft_cli/messages.py

+    Example:
+    -------
+    >>> formatter = JsonFormatter()
+    >>> formatter.format([{"name":"Alice","age":30})


The example code is missing a closing bracket ] and has unbalanced parentheses. Should be formatter.format([{\"name\":\"Alice\",\"age\":30}]).

Suggested change

>>> formatter.format([{"name":"Alice","age":30})

>>> formatter.format([{"name":"Alice","age":30}])

Copilot · 2025-12-05T20:47:19Z

tests/unit/test_messages_emitter.py

-        messages, "_get_log_filepath", lambda appname: tmp_path / FAKE_LOG_NAME
-    )
-
+    monkeypatch.setattr(messages, "_get_log_filepath", None)


Setting _get_log_filepath to None will cause an error when it's called as a function. This should be a lambda or mock function that returns a path.

Copilot · 2025-12-05T20:47:19Z

craft_cli/dispatcher.py


 class _CustomArgumentParser(argparse.ArgumentParser):
    """ArgumentParser with custom error manager."""



[nitpick] This class attribute appears to be added without context. If this is documenting an existing attribute for type checking, consider adding a comment explaining its purpose.

Suggested change

# Type annotation for instance attribute set in __init__; aids type checking.

dharapandya85 requested a review from tigarmo as a code owner August 25, 2025 04:24

lengau reviewed Sep 9, 2025

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lengau requested changes Sep 30, 2025

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dharapandya85 requested review from a team and medubelko as code owners October 1, 2025 11:49

medubelko previously requested changes Oct 1, 2025

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docs/how-to-guides/change-logfile.rst Show resolved Hide resolved

dharapandya85 force-pushed the feat/emitter-data-output branch from f33ec01 to 7a4f4b5 Compare October 23, 2025 13:45

dharapandya85 and others added 2 commits November 27, 2025 14:35

feat(emitter):add structured data output with JSON and table formatting

6aa9fec

feat: Ensure Emitter is initiated before use and fix help argument as…

00bd742

…sertions

dharapandya85 force-pushed the feat/emitter-data-output branch from ae4958a to 00bd742 Compare November 27, 2025 09:05

beliaev-maksim reviewed Nov 27, 2025

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beliaev-maksim reviewed Dec 4, 2025

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dharapandya85 force-pushed the feat/emitter-data-output branch 2 times, most recently from 2d05361 to e64a8dc Compare December 4, 2025 18:38

feat: resolve linting, formatting, and testing issues

2afdf38

dharapandya85 force-pushed the feat/emitter-data-output branch from e64a8dc to 2afdf38 Compare December 4, 2025 18:40

lengau requested a review from Copilot December 5, 2025 20:46

Copilot AI reviewed Dec 5, 2025

View reviewed changes

		# messages.emit._initiated = False
		# messages.emit._stopped = True

	raise ValueError(f"Unsupported format: {format}")
	raise ValueError(f"Unsupported format: {output_format}")

	>>> formatter = JsonFormatter()
	>>> formatter = JSONFormatter()

	>>> formatter.format([{"name":"Alice","age":30})
	>>> formatter.format([{"name":"Alice","age":30}])


		class _CustomArgumentParser(argparse.ArgumentParser):
		"""ArgumentParser with custom error manager."""



	# Type annotation for instance attribute set in __init__; aids type checking.

feat(emitter):add structured data output with JSON and table formatting #380

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dharapandya85 commented Aug 25, 2025 •

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