---
url: "https://vueda.dev/v3/reference/api/py/vueda.workflow.management.commands.updateworkflowmigrations/Command.md"
title: "Command"
---

# Command

## Overview

The base class from which all management commands ultimately
derive.

Use this class if you want access to all of the mechanisms which
parse the command-line arguments and work out what code to call in
response; if you don't need to change any of that behavior,
consider using one of the subclasses defined in this file.

If you are interested in overriding/customizing various aspects of
the command-parsing and -execution behavior, the normal flow works
as follows:

1. ``django-admin`` or ``manage.py`` loads the command class
   and calls its ``run_from_argv()`` method.

2. The ``run_from_argv()`` method calls ``create_parser()`` to get
   an ``ArgumentParser`` for the arguments, parses them, performs
   any environment changes requested by options like
   ``pythonpath``, and then calls the ``execute()`` method,
   passing the parsed arguments.

3. The ``execute()`` method attempts to carry out the command by
   calling the ``handle()`` method with the parsed arguments; any
   output produced by ``handle()`` will be printed to standard
   output and, if the command is intended to produce a block of
   SQL statements, will be wrapped in ``BEGIN`` and ``COMMIT``.

4. If ``handle()`` or ``execute()`` raised any exception (e.g.
   ``CommandError``), ``run_from_argv()`` will instead print an error
   message to ``stderr``.

Thus, the ``handle()`` method is typically the starting point for
subclasses; many built-in commands and command types either place
all of their logic in ``handle()``, or perform some additional
parsing work in ``handle()`` and then delegate from it to more
specialized methods as needed.

Several attributes affect behavior at various steps along the way:

``help``
    A short description of the command, which will be printed in
    help messages.

``output_transaction``
    A boolean indicating whether the command outputs SQL
    statements; if ``True``, the output will automatically be
    wrapped with ``BEGIN;`` and ``COMMIT;``. Default value is
    ``False``.

``requires_migrations_checks``
    A boolean; if ``True``, the command prints a warning if the set of
    migrations on disk don't match the migrations in the database.

``requires_system_checks``
    A list or tuple of tags, e.g. [Tags.staticfiles, Tags.models]. System
    checks registered in the chosen tags will be checked for errors prior
    to executing the command. The value '__all__' can be used to specify
    that all system checks should be performed. Default value is '__all__'.

    To validate an individual application's models
    rather than all applications' models, call
    ``self.check(app_configs)`` from ``handle()``, where ``app_configs``
    is the list of application's configuration provided by the
    app registry.

``stealth_options``
    A tuple of any options the command uses which aren't defined by the
    argument parser.

## `add_arguments` {#add_arguments}

Entry point for subclassed commands to add custom arguments.

### Signature {#add_arguments-signature}

`add_arguments(self, parser)`

#### Parameters {#add_arguments-parameters}

| Name | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| self |  | yes |  |  |
| <span id="add_arguments-param-parser">parser</span> |  | yes |  |  |

### Source {#add_arguments-source}

`server/vueda/workflow/management/commands/updateworkflowmigrations.py:287`

## `handle` {#handle}

The actual logic of the command. Subclasses must implement
this method.

### Signature {#handle-signature}

`handle(self, app_labels, options)`

#### Parameters {#handle-parameters}

| Name | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| self |  | yes |  |  |
| <span id="handle-param-app_labels">app_labels</span> |  | no |  |  |
| <span id="handle-param-options">options</span> |  | no |  |  |

### Source {#handle-source}

`server/vueda/workflow/management/commands/updateworkflowmigrations.py:518`

## `help` {#help}

## Source

`server/vueda/workflow/management/commands/updateworkflowmigrations.py:274`