Introduction to action parameters

A parameter action is an action which has parameters. These parameters are to be entered by the user in a dialog window before the action per se is being run.

>>> import lino
>>> lino.startup('')
>>> from lino.api.doctest import *

The merge action is an example of an action with parameters. When you click the merge button on a ticket, Lino reacts by popping up a dialog window asking for parameters. The action request is submitted only when you confirm this window.

>>> ba ='merge_row')
>>> action = ba.action
>>> p = action.parameters
>>> p['merge_to']
<django.db.models.fields.related.ForeignKey: merge_to>
>>> p['reason']
<django.db.models.fields.CharField: reason>

How to get the layout elements of an action parameter window,

>>> ui = settings.SITE.kernel.default_ui
>>> ui
lino.modlib.extjs (media_name=ext-3.3.1)
>>> lh = action.params_layout.get_layout_handle(ui)
>>> lh 
<lino.core.layouts.LayoutHandle object at ...>
>>> lh.main
<ActionParamsPanel main in lino.core.layouts.ActionParamsLayout on <lino.core.merge.MergeAction merge_row ('Merge')>>
>>> lh['main'] is lh.main
>>> lh['merge_to']
<ForeignKeyElement merge_to in lino.core.layouts.ActionParamsLayout on <lino.core.merge.MergeAction merge_row ('Merge')>>
>>> lh['reason']
<CharFieldElement reason in lino.core.layouts.ActionParamsLayout on <lino.core.merge.MergeAction merge_row ('Merge')>>

You can walk over the elements of a panel:

>>> ses = rt.login('robin')
>>> with ses.get_user().user_type.context():
...     for e in lh.walk():
...        print("{} {}".format(, e.__class__.__name__))
merge_to ForeignKeyElement
merge_to_ct Wrapper
reason CharFieldElement
reason_ct Wrapper
main ActionParamsPanel

Calling a parameter action programmatically

In doctests we sometimes want to call an action programmatically without doing a web request.

In that case we must specify the action_param_values. It must be a dict. Lino checks whether the keys of the dict corresponds to the names of the parameter fields:

>>> pv = dict(foo=1, reason="test")
>>> ar = ba.request_from(ses, action_param_values=pv)
Traceback (most recent call last):
Exception: Invalid key 'foo' in action_param_values of tickets.AllTickets request (possible keys are ['merge_to', 'reason'])

Lino does not validate the values when calling it programmatically. For example merge_to should be a Ticket instance. But here we specify an integer value instead, and Lino does not complain:

>>> pv = dict(merge_to=1, reason="test")
>>> ar = ba.request_from(ses, action_param_values=pv)
>>> ar.action_param_values
{'merge_to': 1, 'reason': 'test'}

Basically the following should work as well. (But nobody ever asked us to make it possible).

>>> o1 =
>>> o2 =
>>> pv = dict(merge_to=o2, reason="test")
>>> ar = ba.request_from(ses, action_param_values=pv)
>>> ar.set_confirm_answer(False)
>>> o1.merge_row.run_from_ui(ar)
>>> 'xcallback' in ar.response
>>> msg = ar.response['message']
>>> print(tostring(msg))
<div class="htmlText"><p>Are you sure you want to merge #1 (⛶ Föö fails to bar when baz) into #2 (☎ Bar is not always baz)?</p><ul><li>1 Dependencies, 3 Sessions, 8 Comments <b>will get reassigned.</b></li><li>#1 (⛶ Föö fails to bar when baz) will be deleted</li></ul></div>