Utils#

Utility functions for the ngapp module

class ngapp.utils.BaseFrontend(link: LinkBase)#

Bases: object

Base class for the frontend

Parameters:: link (LinkBase)

get_query_parameter(name: str)#

Get a query parameter from the URL

Parameters:: name (str)

class ngapp.utils.ComputeEnvironment( *, name: str = 'default', cpus: int = 1, memory: str = '1G', env_type: Literal['venv', 'docker', 'local'] = 'venv', dockerfile: str = '\nFROM python:3.12\nRUN python3 -m venv /venv\nENV PATH="/venv/bin:$PATH"\nRUN pip3 install watchdog websockets wheel pydantic==2.* urllib3 certifi pint colorama fore\nADD wheels /webapp_wheels\nRUN pip3 install /webapp_wheels/*.whl\nRUN unzip /webapp_wheels/ngapp.zip -d /venv/lib/python3.12/site-packages/\n', )#

Bases: BaseModel

Defines the maximal resource usage and type of compute environments on the backend

Parameters:

name (str)
cpus (int)
memory (str)
env_type (Literal['venv', 'docker', 'local'])
dockerfile (str)

class ngapp.utils.Environment(type: EnvironmentType, have_backend: bool, link=None)#

Bases: object

Environment class to store the current environment

Following situations are possible:

1.) Pyodide environment

type = EnvironmentType.PYODIDE have_backend = True | False

This python instance is running in the browser in a web worker and communicates with the main thread via web worker postMessage interface.

The backend might be:

No backend (frontend-only apps)
A full backend with http + websocket interface

2.) Local App environment

type = EnvironmentType.LOCAL_APP

This python instance is running on a local machine and communicates with the frontend (also running locally) via websockets.

3.) Compute environment

type = EnvironmentType.COMPUTE

This is a compute node running a compute function. It communicates with the full backend via http api interface.

4.) Standalone environment

type = EnvironmentType.STANDALONE

Parameters:

type (EnvironmentType)
have_backend (bool)

class ngapp.utils.EnvironmentType(*values)#

Bases: str, Enum

Environment type PYODIDE: Environment is a frontend (running with pyodide in the browser) COMPUTE: We are running a compute function on a separate compute node LOCAL_APP: Backend serves one app locally STANDALONE: Standalone mode with no frontend, used for testing

class ngapp.utils.SettingsFile(path: Path)#

Bases: object

JSON-backed key/value store for small settings files.

This is a generic helper that loads and saves a JSON file on demand and exposes get, set and update utilities. It is used by UserSettings for both the main config.json and any additional JSON settings files in the app’s settings directory.

Parameters:: path (Path)

get(key: str, default=None)#

Get a setting by key, returning default if missing.

Parameters:: key (str)

set(key: str, value, *, autosave: bool = True) → None#

Set a setting value and persist it (by default).

Parameters:

key (str)
autosave (bool)

Return type:

None

update(key: str)#

Return a handler suitable for on_update_model_value.

Example:

nthreads = QInput(
    ui_label="Number of Threads",
    ui_model_value=app.usersettings.get("nthreads", default=None),
)
nthreads.on_update_model_value(
    app.usersettings.update("nthreads")
)

Parameters:: key (str)

class ngapp.utils.UserSettings( app_id: str, path: Path | None = None, app_name: str = 'ngapp', )#

Bases: SettingsFile

Simple persistent storage for user-wide, per-app settings.

Each app gets its own subfolder within the ngapp user config directory, and the main settings are stored in config.json inside that folder.

Additional JSON settings files for the same app can be created via json_file().

Parameters:

app_id (str)
path (Path | None)
app_name (str)

property directory: Path#: Directory that contains this app’s JSON settings files.

json_file(name: str) → SettingsFile#

Return a SettingsFile wrapper for an additional JSON file.

The file is created on first save. .json is appended to name if it does not already end with it.

Parameters:: name (str)
Return type:: SettingsFile

ngapp.utils.call_js(func, *args, **kwargs)#: Call a javascript function in the frontend

ngapp.utils.copy_file(app)#: Create a new file and copy the data

ngapp.utils.default_usersettings_dir(app_id: str, app_name: str = 'ngapp') → Path#

Return the default directory for storing user-wide settings of an app.

The directory is placed inside the ngapp user config directory and named after the given app_id (sanitized to be filesystem-safe).

Parameters:

app_id (str)
app_name (str)

Return type:

Path

ngapp.utils.default_usersettings_path(app_id: str, app_name: str = 'ngapp') → Path#

Return the default config.json path for an app’s user settings.

Parameters:

app_id (str)
app_name (str)

Return type:

Path

ngapp.utils.error(*args) → None#

Log an message to the console

Return type:: None

ngapp.utils.get_job_component()#: Get the current job component of the running job

ngapp.utils.is_production() → bool#

Check if the code is executed in pyodide

Return type:: bool

ngapp.utils.is_pyodide() → bool#

Check if the code is executed in pyodide

Return type:: bool

ngapp.utils.load_file_backend(file_id: str)#

Load a file from backend with given file id

Parameters:: file_id (str)

ngapp.utils.log(*args) → None#

Log a message to the console

Return type:: None

ngapp.utils.new_file(app, data=None)#: Create a new file

ngapp.utils.print_exception( ex, file=<_io.TextIOWrapper name='<stderr>' mode='w' encoding='utf-8'>, )#: Prints the exception and the traceback in red

ngapp.utils.read_file(filename: str | Path) → str#

Read a file from the filesystem

Parameters:: filename (str | Path)
Return type:: str

ngapp.utils.read_file_binary(filename: str | Path) → bytes#

Read a binary file from the filesystem

Parameters:: filename (str | Path)
Return type:: bytes

ngapp.utils.read_json(filename: str | Path) → dict#

Read a file from the filesystem

Parameters:: filename (str | Path)
Return type:: dict

ngapp.utils.replace_app(new_app)#: Replace the current app instance with a new one

ngapp.utils.set_directory(path: str)#

Context manager to change the current working directory

Parameters:: path (str)

ngapp.utils.temp_dir_with_files( data: dict[str, bytes], extract_zip: bool = False, return_list=True, ) → list[Path] | Path#

Context manager to handle files stored in a dictionary

Parameters:

data (dict[str, bytes]) – The dictionary containing the file names and data
extract_zip (bool) – Whether to extract zip files
return_list – Whether to return a single file as list, or the file directly

Yields:

A list containing the file paths objects

Return type:

list[Path] | Path

ngapp.utils.time_now() → float#

Return the current time as a timestamp

Return type:: float

ngapp.utils.warning(*args) → None#

Log a warning to the console

Return type:: None

ngapp.utils.write_file( filename: str | Path, data: str | bytes, binary: bool = False, ) → int#

Write a file to the filesystem

Parameters:

filename (str | Path)
data (str | bytes)
binary (bool)

Return type:

int

ngapp.utils.write_json(data: dict, filename: str | Path) → None#

Write a file from the filesystem

Parameters:

data (dict)
filename (str | Path)

Return type:

None

ngapp.utils.zip_directory(path: str, ignore: str = '*backend*') → bytes#

Zip a directory and return the zip file as a bytes object

Parameters:

path (str)
ignore (str)

Return type:

bytes

ngapp.utils.zip_modules(modules: list[str]) → bytes#

Zip a list of python modules and return the zip file as a bytes object

Parameters:: modules (list[str])
Return type:: bytes

Utils#

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