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| title | sidebar_label |
|---|---|
| Data Entry Flow | Introduction |
Data Entry Flow is a data entry framework that is part of Home Assistant. Data entry is done via data entry flows. A flow can represent a simple login form or a multi-step setup wizard for a component. A Flow Manager is managing all flows that are in progress and handles creation of new flows.
Data Entry Flow is being used in Home Assistant to create config entries.
Flow Manager
This is the class that manages the flows that are in progress. When instantiating one, you pass in two async callbacks:
async def async_create_flow(handler, context=context, data=data)
The manager delegates instantiating of config flow handlers to this async callback. This allows the parent of the manager to define their own way of finding handlers and preparing a handler for instantiation. For example, in the case of the config entry manager, it will make sure that the dependencies and requirements are setup.
async def async_finish_flow(flow, result)
This async callback is called when a flow is finished or aborted. i.e. result['type'] in [RESULT_TYPE_CREATE_ENTRY, RESULT_TYPE_ABORT]. The callback function can modify result and return it back, if the result type changed to RESULT_TYPE_FORM, the flow will continue running, display another form.
If the result type is RESULT_TYPE_FORM, the result should like:
{
# The result type of the flow
'type': RESULT_TYPE_FORM,
# the id of the flow
'flow_id': 'abcdfgh1234,
# handler name
'handler': 'hue',
# name of the step, flow.async_step_[step_id] will be called when form submitted
'step_id': 'init',
# a voluptuous schema to build and validate user input
'data_schema': vol.Schema(),
# an errors dict, None if no errors
'errors': errors,
# a detail information about the step
'description_placeholders': description_placeholders,
}
If the result type is RESULT_TYPE_CREATE_ENTRY, the result should like:
{
# Data schema version of the entry
'version': 2,
# The result type of the flow
'type': RESULT_TYPE_CREATE_ENTRY,
# the id of the flow
'flow_id': 'abcdfgh1234,
# handler name
'handler': 'hue',
# title and data as created by the handler
'title': 'Some title',
'result': {
'some': 'data'
},
}
If the result type is RESULT_TYPE_ABORT, the result should like:
{
# The result type of the flow
'type': RESULT_TYPE_ABORT,
# the id of the flow
'flow_id': 'abcdfgh1234,
# handler name
'handler': 'hue',
# the abort reason
'reason': 'already_configured',
}
Flow Handler
Flow handlers will handle a single flow. A flow contains one or more steps. When a flow is instantiated, the FlowHandler.init_step step will be called. Each step has three different possible results: "Show Form", "Abort" and "Create Entry".
At a minimum, each flow handler will have to define a version number and a step. This doens't have to be init, as async_create_flow can assign init_step depends on diffreent workflow, for example in configuration, context.source will be use as init_step.
The bare minimum config flow:
from homeassistant import data_entry_flow
@config_entries.HANDLERS.register(DOMAIN)
class ExampleConfigFlow(data_entry_flow.FlowHandler):
# The schema version of the entries that it creates
# Home Assistant will call your migrate method if the version changes
# (this is not implemented yet)
VERSION = 1
async def async_step_user(self, user_input=None):
# Do something
Show Form
This result type will show a form to the user to fill in. You define the current step, the schema of the data (using voluptuous) and optionally a dictionary of errors. Title and description of the step will be provided via the translation file. Where this is defined depends on the context of the data entry flow.
class ExampleConfigFlow(data_entry_flow.FlowHandler):
async def async_step_user(self, user_input=None):
# Use OrderedDict to guarantee order of the form shown to the user
data_schema = OrderedDict()
data_schema[vol.Required('username')] = str
data_schema[vol.Required('password')] = str
return self.async_show_form(
step_id='init',
data_schema=vol.Schema(data_schema)
)
After the user has filled in the form, the step method will be called again and the user input is passed in. Your step will only be called if the user input passes your data schema. When the user passes in data, you will have to do extra validation of the data. For example, you can verify that the passed in username and password are valid.
If something is wrong, you can return a dictionary with errors. Each key in the error dictionary refers to a field name that contains the error. Use the key base if you want to show an error unrelated to a specific field. The specified errors need to refer to a key in a translation file.
class ExampleConfigFlow(data_entry_flow.FlowHandler):
async def async_step_user(self, user_input=None):
errors = {}
if user_input is not None:
# Validate user input
valid = await is_valid(user_input)
if valid:
# See next section on create entry usage
return self.create_entry(...)
errors['base'] = 'auth_error'
# Use OrderedDict to guarantee order of the form shown to the user
data_schema = OrderedDict()
data_schema[vol.Required('username')] = str
data_schema[vol.Required('password')] = str
return self.async_show_form(
step_id='init',
data_schema=vol.Schema(data_schema),
errors=errors
)
Multi-step flows
If the user input passes validation, you can again return one of the three return values. If you want to navigate the user to the next step, return the return value of that step:
class ExampleConfigFlow(data_entry_flow.FlowHandler):
async def async_step_init(self, user_input=None):
errors = {}
if user_input is not None:
# Validate user input
valid = await is_valid(user_input)
if valid:
# Store info to use in next step
self.init_info = user_input
# Return the form of the next step
return await self.async_step_account()
...
Create Entry
When the result is "Create Entry", an entry will be created and passed to the parent of the flow manager. A success message is shown to the user and the flow is finished. You create an entry by passing a title and data. The title can be used in the UI to indicate to the user which entry it is. Data can be any data type, as long as it is JSON serializable.
class ExampleConfigFlow(data_entry_flow.FlowHandler):
async def async_step_user(self, user_input=None):
return self.create_entry(
title='Title of the entry',
data={
'something_special': user_input['username']
}
)
Abort
When a flow cannot be finished, you need to abort it. This will finish the flow and inform the user that the flow has finished. Reasons for a flow to not be able to finish can be that a device is already configured or not compatible with Home Assistant.
class ExampleConfigFlow(data_entry_flow.FlowHandler):
async def async_step_user(self, user_input=None):
return self.async_abort(
reason='not_supported'
)
Translations
Data entry flows depend on translations for showing the text in the forms. It depends on the parent of a data entry flow manager where this is stored.
Initializing a config flow from an external source
You might want to initialize a config flow programmatically. For example, if we discover a device on the network that requires user interaction to finish setup. To do so, pass a source parameter and optional user input when initializing a flow:
await flow_mgr.async_init('hue', context={'source': data_entry_flow.SOURCE_DISCOVERY}, data=discovery_info)
The config flow handler will not start with the init step. Instead, it will be instantiated with a step name equal to the source. The step should follow the same return values as a normal step.
class ExampleConfigFlow(data_entry_flow.FlowHandler):
async def async_step_discovery(self, info):
# Handle discovery info