Help Texts

help text

A short explanation to be displayed as tooltip when the user hovers over a form field, a menu item, or a toolbar button.

Help texts should be (1) helpful to the end user, (2) translated and (3) maintainable. Lino provides several approaches for reaching these goals.

The primitive way

Help texts can be defined and maintained by the application developer by setting the help_text attribute of a field, actor or action. As a developer you should wrap that string into gettext() to have it translatable. Fictive example:

from lino.api import dd, _

class MyModel(dd.Model):
    """MyModel is an important example."""

    universe = models.CharField(_("First field"),
        blank=True, max_length=100, help_text=_("""
The first field contains an optional answer to the
question about life, the universe and everything.
"""))

Having help texts maintained by the end users

Help texts can be customized locally per site by the end users as customized help text. This feature is not being used seriously on any known production site.

Using the help texts extractor

In bigger projects we want to differentiate between application development and authoring of end user documentation. That's why the application developer can delegate help text maintenance to the documentation maintainer.

This is where we use the help texts extractor.

help texts extractor

A Sphinx extension that extracts help texts from your Sphinx documentation to help_texts.py files, which Lino will load at startup.

Writing the help texts

With the help texts extractor you write the help texts in your documentation using prosa style:

.. class:: MyModel

    MyModel is an important example.

    .. attribute:: universe

        The first field contains an optional answer to the
        question about life, the universe and everything.

        This field is a simple char field. Blabla more documentation.

Write help texts so that extractor can find them

Note that only the first paragraph of the content of every class and attribute directive is taken as help text, and that any formatting and links are removed.

Extracting the help texts

When you run inv bd on a Sphinx doctree that has help_texts_extractor installed, Sphinx takes the first paragraph of every object description in your Sphinx documentation and writes it to a help_texts.py file.

Configure the help texts extractor in the conf.py of your doctree by adding lino.sphinxcontrib.help_texts_extractor to your extensions and defining a help_texts_builder_targets setting. For example:

extensions += ['lino.sphinxcontrib.help_texts_extractor']
help_texts_builder_targets = {
    'lino_algus.': 'lino_algus.lib.algus'
}

Translate help texts

After having extracted help texts, the application developer can run inv mm and start translating them.

Loading help texts at startup

Lino will load these help_texts.py files at startup and "inject" them to the fields, actions and actors as if they had been defined by the application code.

More precisely, when a Lino Site initializes, it looks for a file named help_texts.py in every plugin directory. If such a file exists, Lino imports it and expects it to contain a dict of the form:

from lino.api import _
help_texts = {
    'foo': _("A foo is a bar without baz.")
}

Advantages

  • Better readability, better maintainability.

  • As an application developer you don't need to worry about Python syntax consideration when editing your help text

  • Same source is used for both the docs and the user interface. You don't need to write (and maintain) these texts twice.

The help_texts.py file

help_texts.py

The help_texts.py file contains object descriptions to be installed as help texts of user interface widgets. The file is automatically generated from the documentation.

The file is generated only by a full build, i.e. when all pages of the doctree were built. If you want to be sure, you must run inv clean before running inv bd. So in practice you will say inv clean -b bd

help_texts_builder_targets

A setting in the conf.py of your doctree. A dictionary mapping beginnings of module names to the full name of the Python package where the help_texts.py is to be written.

See also

Accessing help texts from your code

>>> import lino
>>> lino.startup('lino_book.projects.min2.settings.doctests')
>>> from lino.api.doctest import *

Here is how Lino internally accesses the help text of a database field:

>>> fld = rt.models.contacts.Partner._meta.get_field('name')
>>> print(fld.help_text)  
The full name of this partner. Used for alphabetic sorting.

Above text is the first sentence extracted from the documentation of the lino_xl.lib.contacts.Partner.name field.

You can show and test all help texts of a model or actor in functional specifications using the show_fields function:

>>> show_fields(rt.models.contacts.Partner)
+---------------+----------------------------+-----------------------------------------------------------------+
| Internal name | Verbose name               | Help text                                                       |
+===============+============================+=================================================================+
| email         | e-mail address             | The primary email address.                                      |
+---------------+----------------------------+-----------------------------------------------------------------+
| language      | Language                   | The language to use when communicating with this partner.       |
+---------------+----------------------------+-----------------------------------------------------------------+
| phone         | Phone                      | The primary phone number.                                       |
+---------------+----------------------------+-----------------------------------------------------------------+
| gsm           | GSM                        | The primary mobile phone number.                                |
+---------------+----------------------------+-----------------------------------------------------------------+
| city          | Locality                   | The locality, i.e. usually a village, city or town.             |
+---------------+----------------------------+-----------------------------------------------------------------+
| addr1         | Address line before street | Address line before street                                      |
+---------------+----------------------------+-----------------------------------------------------------------+
| street_prefix | Street prefix              | Text to print before name of street, but to ignore for sorting. |
+---------------+----------------------------+-----------------------------------------------------------------+
| street        | Street                     | Name of street, without house number.                           |
+---------------+----------------------------+-----------------------------------------------------------------+
| street_no     | No.                        | House number.                                                   |
+---------------+----------------------------+-----------------------------------------------------------------+
| street_box    | Box                        | Text to print after street number on the same line.             |
+---------------+----------------------------+-----------------------------------------------------------------+
| addr2         | Address line after street  | Address line to print below street line.                        |
+---------------+----------------------------+-----------------------------------------------------------------+
| prefix        | Name prefix                | An optional name prefix. For organisations this is inserted     |
|               |                            | before the name, for persons this is inserted between first     |
|               |                            | name and last name.                                             |
+---------------+----------------------------+-----------------------------------------------------------------+
| name          | Name                       | The full name of this partner. Used for alphabetic sorting.     |
+---------------+----------------------------+-----------------------------------------------------------------+

Don't read on

>>> from lino.api import _
>>> from lino.utils.jsgen import py2js
>>> x = dict(tooltip=_("""This is a "foo", IOW a bar."""))
>>> print(py2js(x))
{ "tooltip": "This is a \"foo\", IOW a bar." }